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This section of Isetta Tech will be updated on a semi-regular basis. Please use the Feedback link to let us know what issues you would like to see addressed, correct us on any bogus info we've dished out or suggest other/better ways to get those Isettas back on the road where they belong.
Revised September 2005
A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z
Click on a letter that corresponds to a topic that begins with that letter.
A
AIR CLEANER CANISTER
Your canister is basically an elongated coffee can that bolts to the rear fender (mud/splash guard) bracket and runs from side-to-side. It has a rear inlet tube welded on at a right angle that connects to the external air intake via angled rubber hose, an early Ram-Air design if you will. The canister connects to the carburetor via a J-shaped hose on the engine side. This J-shaped hose clamps onto the canister cover containing the air filter.
If you don't do anything else in the way of maintanence on your Isetta, make sure you change the oil and at least clean, if not replace, the air filter on a routine basis.
B
BATTERY
Many different types of batteries have been sucessfully used in Isettas. The Isetta electrical system calls for 12 volt, 31 amp battery with negative ground. We have a Harley-Davidson Non-spillable (sealed) battery in our car. It's H-D part number 65989-97. This battery measures 7" wide by 6" tall by 3 1/2" deep and retails for about $75.00. With it's compact size, there's no worry about fitting in the battery box or being too tall to fit under the seat. Life expectancy is in the 3 year range. Westco Battery offers a broad range of batteries and related products that are perfect for many micro/mini cars. You can search on motorcycle batteries and plug in BMW to see their offerings or give them a call to see what they suggest.
Other battery options that have been used include Sear's (and other brands) riding lawn mower / ATV batteries. Some models are slightly less money than other choices but may not last as long. You will probably find that most of these types of batteries have the removeable caps to add distilled water to the cells, one more maintenance issue to deal with. Most we've seen also require that the electrolyte be added to the battery once you purchase it so it may not be ready to use off-the-shelf. One item that we didn't care for on these units was the ventilation tube. This tube runs down one side of the battery and it's name is self-explanatory. There's just something about having battery acid fumes vented under the seat of the car that isn't appealing. One could always drill a hole in the battery box and vent it outside but punching a hole in the car wasn't an option.
You might consider picking up a good battery charger at the same time. Westco sells a fully automatic charger, the AccuMate Power Charging System. It's their model number LS6/1.2 and sells for $60.00. It's a small, switchable, fully automatic charger for 6V / 12V small batteries. This unit won't allow you to accidentally reverse polarity and comes with a neat pigtail adapter that you can attach to the battery and leave under the seat. When need be, just plug the pigtail into the charger and plug the charger into the wall. When the green LED comes on, you're done. An LED will also indicate that the battery is no longer chargeable and should be replaced. It will also sit there for months and maintain a full charge without burning your car, garage and/or house to the ground. They also include the old standby alligator clips too if you move it around from one vehicle to another.
One word of wisdom on selecting a battery is to make sure that you don't get one that's too tall. That includes selecting one that has it's posts either recessed or side mounted so there's no danger of having the bottom of the seat springs come into contact with the posts and causing a potentially disastrous short. Assuming that you intend to use the factory grounding stud in front of your battery box, you may also find that having the negative post to the right (passenger) side allows a neater battery cable installation too. Finally, you might want to put some sort of mat under your battery. The acid-free mats seem impossible to find any more in our area. We went to the hardware store and bought a square foot of 1/16" neoprene rubber sheet and cut a mat to fit our box. Some owners, this one for instance, also cut a square of the same neoprene punched several holes around the outer perimeter and tie-wrapped it to the bottom of the seat springs directly above the battery just to be safe. More than one Isetta has burned to the ground or has been severely damaged due to those seat springs shorting across the battery posts. Electric chairs have their place but your Isetta is not one of them.
BATTERY BOX
Public Enemy #1 when it comes to rotting and rusting out. New battery boxes are easy to come by through parts suppliers. The target price should be around $50.00. Being a fairly simple item, a sheet metal shop should be able to make one up for you as well.
If your floorboard has rotted away around the box, you'll need to replace that sheet metal so your new box fits the same rectangular cutout in the floorboard rather than install a larger box. Why? First, if you should go to a larger (deeper front-to-back) box, you'll be chewing up the real estate where your voltage regulator is mounted behind the battery box. If that happens, there won't be sufficient room between the back of the box and the underseat heater for the regulator to fit. You'll have to improvise and mount it off-center to the passenger side of the floorboard or the inside of the spare tire well. This will work OK ... just stand advised before you get started. Second, there is a lateral steel brace welded to the underneath side of the floorboard behind the box. You would have to remove this brace and relocate it.
One nice touch to add to that new box is a mat, preferrably of the acid resistant variety. These mats seem to be disappearing from the auto parts stores' inventory these days though. We bought a 1' piece of neoprene rubber stock from the hardware store and cut one from that. Works like a charm for a buck and a half.
Another area where we've seen lack of attention is the battery tie-down strap. The original factory boxes had a small wing on either side where a threaded, L-shaped rod was attached, threads pointing up. Once the battery is installed, a flat bracket is placed on top of the battery. The threaded part of those vertical rods goes through each end of the bracket and are secured by wing nuts on either side. That battery isn't going anywhere. Many people have stuffed foam rubber and/or pieces of wood around their batteries to keep it in place. Some have rigged up a bungee cord or two to do the job as well. That may be better than nothing but the factory setup is the way to go.
BRAKES
Overview
Note: If you have a Brighton-built, British Isetta, your car has Girling brake components installed. Please disregard this section as it doesn't apply to your car! The Isetta utilizes a simple design that's easy to work on. On US Export models, the front brakes use ATE wheel cylinders with a 17mm bore. The two cast aluminum brake shoes rely on riveted lining for stopping power and there are two identical springs, one top and one bottom, that tie the two together. Two adjustments can be made here. The angle of the shoe/linings can be adjusted for parallel contact with the inside of the drum via small screw on each shoe. With only 50 square inches of braking surface, you want these shoes perfectly parallel to the drum. The conical brake adjuster at the bottom of the assembly is used to regulate the distance between the shoe/lining and the drum.
While BMW's Isetta sales brochure specifically states "four wheel brakes", the rear has only one brake mounted on the right rear. That's three total.Given that it stops a live axle that both rear tires are mounted to, the claim is accurate but seems somewhat misleading. The rear brake is similar to the front units but uses a cylinder with a smaller, 12mm bore. In addition, there are two studs, one on the top of each shoe, that the actuating levers for the hand brake cable fasten too. The spring that fastens the shoes together at the top differs from the other five brake springs in that the eyelets are rounded to clip into a machined slot in each of the studs and secure those levers.
The master cylinder, also an ATE unit, is bolted to the middle frame crossmember and is actuated by an adjustable rod that connects to the brake pedal. The brake lines have 10mm x 1mm threads and fasten into 18" brake hoses at all three ends. The system calls for DOT Type 3/4 fluid. ATE offers their own branded fluid but any reputable brand will do the job for you.
Master and Wheel Cylinders
One of the most common problems with Isettas that have been setting up is the demise of the braking system. Brake fluid takes on moisture over time and that moisture is what ruins the pistons in your master and brake cylinders. Old cylinders can leak and/or be sluggish. Many simply freeze up. You have several choices of what you can do to get your brake system back to looking like this:
• Do the work yourself, or
• Send them off to a rebuilding facility , or
• Buy new wheel cylinders from Isetta parts suppliers
Let's say you're on a budget or just like to do the work yourself. Parts suppliers can get you the rebuild kits needed for the wheel and master cylinders. The two front wheel cylinders are identical and use a 17mm bore. The single rear cylinder uses a smaller 12mm bore. In a nutshell, the cylinders need to be removed, dismantled, thoroughly cleaned and lightly honed to remove any pitting that may have occured from moisture. Be careful when removing stubborn pistons. These things are made out of pot metal and the little rectangular protrusion on the outside end can snap off it you try to twist it too hard. Use a heat gun and lubricant on these parts and then give it another try. Be sure to take those bleeder valves out and be careful with them as well. Use some PB Blaster and a heat gun to loosen the threads up first. Having to hog out broken valve threads is a pain and one you can avoid if you're patient.
White Post Restorations is a well-respected organization that provides all type of resto services including brake and master cylinder rebuilds. They can also brass-sleeve your cylinders to eliminate that corrosion and pitting too. Check out their Web site or give them a call at (540) 837-1140 for a quote on having those brake cylinders done by professionals. Another company that can help is Sierra Specialty Automotive. They can be reached by phone at (800) 4-BRASS-1 or (800) 427-2771.
You may find that the quote for a truly shot set of cylinders isn't that far off from just buying a fresh new set. Suppliers carry the original ATE units that bolt right onto your car. As of March 2005, wheel cylinders are running in the $90.00 each range, $190.00 for a master cylinder assuming you're sending yours back as an exchange, or core, unit. For what it's worth, we know of at least two former Isetta owners who simply installed early VW Beetle wheel cylinders in their cars at a fraction of the cost. If you want a second opinion, take those Isetta cylinders to your local Euro auto parts store and compare them to the early VW Beetle/Ghia/Bus units. The ones we've seen look virtually identical but have the bleeder valve at the bottom so proceed with caution on this one. Upside down, no worky. You can also visit California Imports' Web page and take a sneak peak at 'em. You're looking for a 1952-1957 Beetle / Ghia wheel cylinder part number VWC-113-611-053 (rear) and VWC-113-611-055 (front). They run around $40.00 each, substantially less than other sources charge. Better than that, why not just go to your local VW repair shop. If they're working on vintage models, and you can bet they are, they'll have these on the shelf. That may be the quickest, safest and possibly cheapest bet of 'em all. Whatever you do, get the right ones. Your brake system is no place to be taking shortcuts and pinching pennies!
Make note that we have not used the VW wheel cylinders and do not have first hand experience with them! If anyone out there can chime in on this topic, please follow up with us so we can get the word out on this potential option.
One other note that's worth slipping in here. There has been a debate over using front wheel cylinders on the rear. At a couple of points in time, new rear cylinders were impossible to come by so some folks just popped a front unit on their rear brakes. The fronts and rears use identical bolt patterns and physically fit either way. The debate centered around the issue of the rear brake locking up with the larger, 17mm cylinder. One side said it was dangerous, the other shrugged it off. It's been noted that the front brakes on an Isetta do approximately 80% of the stopping with 20% of the task going to the rear unit, not unlike scores of other more conventional cars. We're not about to jump into the middle of that one but wanted to make you aware that it's caused more than one tongue-wrestling match. One fine-tuning tip that's been passed along is to have the rear brake shoes engage just slightly before the front shoes to give yourself a bit of a stopping advantage. Remember, on a good day, you only have 50 square inches of brake lining working for you.
Lines and Hoses
Moving right along to the brake lines and hoses, you may find deteriorated rubber hoses and crimped brake lines. New brake line kits are available at under $50.00, come cut to the correct length and are made from a semi-stainless steel material referred to as "cunifer". If you're gonna hit the parts store and buy 'em off the shelf, the line lengths are as follows: rear=44", right front=40" and left front=20". 18" brake hoses with 10mm x 1mm metric male/female fittings work fine and allow for flexibility and movement of both steering and chain drive. If you want to trick your car out a bit, why not get a set of 3 braided stainless steel hoses from Bavarian Autosport? It's their part number SSBH-18MF. This item is not currently listed on their Web site but you can always call them at (800) 535-2002 to check availability. Another option is to visit California Imports and check out their part number C12-5585-12. That's a 19" stainless steel brake hose for early Beetle, Ghia and Bus.
One word of warning about off-the-shelf brake lines. While the lines themselves are functionally OK, you'll find that the threaded ends that attach to the hoses are about half again longer than the factory threads. What will happen is the the female hose threads only go down so far on the longer threads of the lines. So what? Well, when you put your two front L-brackets and retainer springs in the middle, the line/hose won't compress, or even reach, that U-spring. Even worse, the hose won't be able to pull the line threads as far as they need to go for a tight fit. Your line/hose will just rattle around in there. Take your hose, L-bracket and spring to the parts store if you're considering this. You'll see what we mean. Perhaps there are shorter threaded brake lines or longer retainer springs. We had no luck finding them in the parts stores in Austin.
Replacement of those lines can either be a snap or a real pain depending on the disposition of your car. The 'snap' part? That's if you're body is off of the frame. You'll need to make multiple bends and test fitting is a must to have it come out right. The 'real pain' part? It's a difficult procedure if you're working under the car but it can be done. The two most critical bends you'll have to make are for the lines exiting the master cylinder on top. They come up at an angle and must be bent back down so they clear the bottom of the floorpan on both sides. In addition, the right line must come forward, around and in front of the battery box. Both lines must then come through the middle frame crossmember, under the frame and then forward to the outside where they will attach via L-bracket to the lower outside of your wheel wells. That L-bracket and associated spring also holds the line and hose tightly together.
Finally, be sure and use the correct brake fluid. ATE makes their own brand of DOT 3/4 fluid although any quality brand should do a fine job for you.
BRAKES, ADJUSTMENT
Adjusting the brakes on your Isetta is a pretty straightforward process. There are two points that will require your attention. We recommend adjusting the shoes for perfectly parallel contact with the inside of the drum first. This is accomplished by turning the small, slotted screw located in the approximate middle of each brake shoe either in or out until the surface of the lining and drum are flush. Turning this screw clockwise will move the outer edge of the shoe in an outward arc, vice versa for counter-clockwise. An easy way to check your work is to get a piece of chalk and mark a stripe across each lining at the top, middle and bottom. Make your first adjustment, put the drum and tire back on the car and give it a spin while someone steps on the brake pedal. Remove the tire and wheel and look to see where the chalk is wiped off the lining. If you see chalk left on the inside of the lining, you know that the shoe is cocked to the inside too much. Just give your adjusting screw a turn or two in the clockwise direction and repeat the process, making sure to put new chalk marks over your old ones. Once you have a "clean sweep", tighten the locking nut down on the adjusting screw and move on to the next shoe. If this is a first pass, remember that those linings may not be a perfect 360. The thing that really did it for our car was cruising down the street at 30-35 MPH and literally slamming on the brakes. Multiple times. You'll be surprised at how fast those new shoes get acclamated to their new environment!
The other adjustment moves the linings either closer to or away from the drum surface and is accomplished with the brake adjusting screw at the outside bottom of each brake backing plate. Turning this "coneheaded" screw in (or clockwise) will push the shoes outwards toward the inner drum surface. Counter-clockwise will back it away from the drum. You'll probably want it as close as you can get it to the drum for quick action. Spin your tire and turn that adjusting screw clockwise until the tire comes to a stop. Now back the screw off while giving the tire another spin. At the point you no longer have any resistance, audible or otherwise, take a wrench and tighten the locking nut down while holding the square head steady with a crescent wrench. Do this two more times and your finished (for now). You'll want to check this adjustment periodically as the new linings adapt to their environment as well as compensate for normal wear.
"Hey, that's cool but when I back the lower adjusting screw out, the tire turns OK but there's a lingering scraping/brushing sound once per revolution. What's wrong?" Your brake is telling you that the shoe(s) need a bit more attention in regards to being perfectly parallel to the drum surface. Go back and try the chalk routine. You'll probably find that this will take a bit of tweaking to get it perfect but it's pretty quick work when all is said and done. This sound could also be atttributed to a lining that has a slight high spot in it. "Easy for you to say! I've tried everything and it still has a subtle brushing sound I can't get rid of". That could be a couple of things. One, did you have your drums turned when you had the new linings installed? If not, you're probably fighting a lost cause. Have those drums turned. "Of course I had them turned! What's your number-two bright idea?" Maybe you didn't have the linings arc'ed. If those linings aren't riveted in starting from one end working to the other, they can pooch up, very slightly, towards the middle. Nothing is perfect either. That's the reason to lay out a few extra bux to have them trued up and factor that out of the equation. You're gonna have to do better than that." Did you have that wheel and tire tightened down good and snug or did you just have it on finger tight? If just finger tight, it may be rotating in an uneven pattern and causing some very slight wobble between the lining and drum."Been there, done that". Drive your car. Take it to a low/no traffic area. Use your brakes frequently over short hauls and vary the speeds you are stopping from. Let those new linings get used to having to do some work instead of sitting in a cardboard box on your shelf. Beats the heck out of yard work!
You'll probably find that the combination of all-of-the-above will do the trick. Even with all of the adjusting we did, that slight rubbing sound was still there. One owner asked, "Have you come crusing down the street and just flat-out slammed on the brakes in front of your house a few times?". No, we hadn't. But we did. Somewhere between that excercise and just putting a lot of short haul starting and stopping, the brakes became obviously better over a fairly short period of time. Just be sure to go back and check your adjustments occasionally, especially in the first 500-1000 miles you put on your car.
BRAKES, HANDBRAKE INSTALLATION AND ADJUSTMENT
This is an installation that has to be done in the correct order to be successful. First, you'll want to attach the cable to the rear brake. After you pass your cable through the slot at the bottom of the backing plate, be sure and crimp that small arm the cable passes through so it doesn't pull out on you. Remember, you may be in a panic or be parked on an incline when you need this brake so make sure it's good and tight back there.
Next, route it across the top of the right rear spring, over the rear of the frame and through the hole in the firewall in the spare tire area. Make sure you have a new rubber grommet in that hole to eliminate chafing and wear on the outer part of the cable. Run the cable forward to the outside of the left wheel well.
Next, make sure that your rear brake drum is off of the car. This will allow the rear shoes to expand outward as you pull the cable up front. Failure to remove the drum will make this task literally impossible. Now comes the tug-of-war part. Many Isetta restorers have trimmed around 1/4" of the cable's outer cover back from the threaded piece that fits into the handbrake mounting plate to allow for a bit more leverage since it will expose that much more of the actual cable inside. We didn't have to do that. Just take a pair of vice grip pliers and clamp it down good and tight on the very front of the cable. Now, get your mounting plate and lay it on the floor. Pull that cable out as hard as you can until you have enough to drop through the slot on the side of the threaded collar the cable fits into. Let go and take a break.
Next, place that small, round slotted steel piece on the end of the cable until the cable end fits into it snuggly. You'll need to grab your brake handle and spread the two tangs at the bottom (the ones with the round holes where that steel piece fits) apart. Now you can place that steel piece, cable end inserted, into place and crimp down around it so the steel piece has no where to go. Install your mounting plate/cable assembly to the wheel well, position the hand brake lever on its pivot, replace the steel retainer plate and cover and you're done. You'll be amazed, after all of that pulling, how easy it operates once it's installed.
To adjust your hand brake, put your rear brake drum back on the car along with the right rear tire. You're looking to have that tire stop from rotating at 3-4 clicks of the handle. That's where the threaded adjustment collar comes into play. Back it out a few turns at a time, if need be, and have an assistant spin the rear tires. It shouldn't take much adjusting, especially if you've had your brakes relined. Check from time to time to account for wear of the rear linings.
What if I've backed the inside threaded collar out and it still doesn't stop on click 3 or 4? That probably means that your rear brakes haven't been adjusted yet. The culprit will most likely be the brake adjuster at the bottom and you'll probably find that it is turned too far out, leaving a greater distance between the shoe and drum than is desirable. Just loosen the nut that secures it and turn it clockwise until you hear the shoe dragging on the drum (or the rear tire quits turning). Now, back it off counterclockwise until the tire rotates smoothly with no audible sound. Try your hand brake again and see if that didn't do the trick.
Finally, there are two methods of applying your brake. One is to grab it and rachet it back to the stop position. The other is to push the release button in and do the same thing, the silent treatment. The latter is the preferred method. Why? If you use the rachet method enough times, you will eventually wear the chisel point off the top of the spring-loaded actuating rod inside the brake handle. When that point is gone, there is nothing left to engage your hand brake and keep it there.
BRAKES, RELINING
As we have mentioned, the braking system in a neglected Isetta may well be one of the worst parts of the car. While the master and wheel cylinders are probably at the top of everyone's list, the brake linings have to be dealt with too. This is no place to cut a corner and brake linings being relatively inexpensive, go for six new ones.
On higher mileage cars (ours had 34,050 on the odometer) you can bet that the brakes have had at least one new set of linings since it left Munich. In order to remove the old lining, the rivets must be drilled out in order to make way for new ones. If this is the case, it's almost a sure bet that at least some of the original rivet holes in the shoes have been enlarged by this drilling process. You may find that the new rivets available from suppliers are both too small in diameter and/or not long enough to properly cinch down on the inside of the shoe and hold the new lining in place. Here's something you can do that's cheap and works.
Take your shoes (hopefully you've cleaned them up and media blasted them ahead of time) to the brake shop, have them pull out their rivet selection and determine which size is best suited for your linings and shoes ... the larger in diameter the better. Now, check to see if the rivet will be able flare out enough on the inside of the shoe to hold the new lining. If not, make a run to the hardware store and buy the appropriate number of small washers, preferrably stainless steel, with inside diameters corresponding to the new rivet's diameter. Be sure to take a rivet with you to size the washers. All your brake shop has to do is place those washers on the inside of the shoe, drop the rivet in from the lining side, pull the trigger and, bingo, you'll have a good tight fit. The shop went so far as to drill all of the holes in the shoes to one consistent size so every rivet got a washer. It's a very neat job when done correctly. Our shop also suggested arcing the new linings to ensure a true 360 degree arc for maximum contact with the drum surface and longer life in general.
By the way, don't ever used bonded (glued) linings!
C
CARBURETOR
For the most part, BMW equipped Isettas with the Bing 1/22/98 carburetor. If you're wondering how they came up with the model number, Bing tells us that the "1" is virtually meaningless, the "22" refers to the venturi size in millimeters and the "98" points to a 300cc BMW (as opposed to British, Iso, Velam and Romi)Isetta. Bing also refers to this particular carb as a Type 121, used on the 300cc models. According to Bing's manual, variants of the 1/22/98 that were also used on 250 and 300cc motors are as follows: 1/24/49 (250), 1/22/97 (250), 1/22/131 (250 & 300), 1/22/161 (250 & 300) and 1/24/93 (300). With the exception of the main jet, jet needle and clip position, all other parts are virtually the same.
It's a simple little device that seems to work well if cared for but can give you fits getting it dialed in. We're not professing to be Bing experts here, mind you. As of this posting, we're speaking largely from consistent input we've gathered from other Isetta owners along with our own experiences.
Our carburetor came in two Tupperware bowls stuck to the bottom in gasoline residue. The fuel bowl was missing along with other parts. Fortunately, the carb body and guts were there. That's important given the fact that new Isetta carbs are not to be had. You either send Bing your core for rebuilding or swap your core for one of the suppliers' rebuilt units. If you hit in on the right day, you might get lucky and find an NOS/rebuilt unit up for bid on eBay.
The Bing Agency operates a facility in Council Grove, Kansas. Their phone number is (800) 309-2464 (orders only) or (620) 767-7844 for pre and post-sales tech information. You can check them out on the Web right here. They do nothing but Bing work and they do it very well. Our carb took right at a month from start to finish. We got the works ... actually, we had no choice. They bead blasted and clear coated the carb. All internal components were replaced as well as an external appearance kit (it needed it!). They had the missing fuel bowl (ouch!) which was installed and tested. We even got a couple of feet of their clear alcohol-proof fuel line which doesn't require any clamps. If you're into doing it yourself, you can buy the rebuild kit and owner's manual from them at a reduced price, too.
When the engine was rebuilt and fired for the first time, it started right up and the carb seemed to be dialed in. As the motor warmed up and began sounding even stronger, we noticed that it was running a bit rich due to the subtle presence of sooty, black exhaust while bringing the revs up. Then came the leaks. Seems like this is a way of life for Isettas. The gaskets were brand new and looked OK but leaked fuel just the same ... not a good thing.
Terry Sayther of Terry Sayther Automotive suggested that we pull that fuel bowl assembly off and check the mating surfaces to make sure that they were flat. It was a fast and easy process to determine that the surfaces needed some attention. We put a piece of 600 grit sandpaper on a flat work table and gently worked the surface back and forth for a few passes. A visual inspection revealed the obvious peaks and valleys that were causing the problem. We continued the sanding process until the major descrepencies were gone, added a light coat of Blue Magic Polish to the sandpaper and worked the surfaces to a mirror finish. Back on the car, it was dry as a bone ... all in about 10 minutes. You might want to consider buying a backup gasket set from Bing and keeping them in your service spares. The individual gaskets are all under a dollar. They're also included in Bing's rebuild kit.
Now to the running-rich problem. There are several areas to check in regards to this foible. First, pull the jet needle out of the slide pot and make sure that the e-clip is installed on the second notch from the top. There should be a total of four notches in this long, slender, tapered piece. The top notch is the leanest setting, fourth (bottom) notch being the richest. This setting affects mid-to-upper range power and that's where we saw the sooty jetsam eminating from the muffler. If you didn't replace that jet needle, get a magnifying glass and take a look at the area of the needle that seats with the jet. If that needle is an old one, there's an excellent chance that it's pitted. If that's the case, throw it out and replace it with a new one from Bing. When rebuilding your carb, make sure you get the start and idle jets installed back in their original positions. They look identical and can be easily reversed. The start jet is a #55, the idle jet a #35. The #55 start jet goes to the back, or engine, side of the carb. The #35 idle jet goes to the outside of the carb.
Next, you'll want to find the sweet spot between the idle speed and your idle air screw. The idle speed screw is on the left rear side of your carburetor with the slots facing down. There is a spring between the head of the screw and body of the carb. Turning the idle speed screw clockwise, or into the carb, will raise the revs. The idle air screw is located on the outside front of the carb and sits nestled just to the right of the fuel bowl. It uses a lock nut rather that a spring to secure it once properly adjusted. The factory calls for 1 1/2 to 2 turns out from the carb. Your engine will probably idle just fine regardless of where the idle air speed screw is set, unless it's all the way in, but will bog, fall flat on its face and/or backfire through the carb on acceleration if it's too far out.
We prefer a higher idle setting, somewhere in the 800-1000 RPM range. Our engine seemed to be happier accelerating from a dead stop with more revs at idle. Once you set your initial idle speed, you can turn the idle air screw in until you hear the motor start to decrease in revs. Now, back it out a bit and try the accelerator. You should get instant revs out of the the engine. If it balks, you might set the idle speed a bit higher and go through the same process again. It helps to have an associate manning the gas pedal during this procedure. Also, make sure the engine is warmed up for about five minutes before you get started. Trying to accomplish this with a cold engine is a fairly hopeless scenario.
One other area that can cause problems is the choke. Our choke seems to know when it drops below 65 degrees. You have to use the choke at about half-open for a few seconds, to get the engine started at or below that temperature. In warm weather, you never need to touch it. If your choke piston, or puck, is old and cracked, you can expect trouble and erratic performance. Make sure you replace this part. Bing part number 22-935 will run you all of $5.00. You can check yours by looking at the bottom of the piston and verifying that it has a small round indention in it. If it doesn't, it's worn out but you'll probably already know that from your engines cantakerous behavior, if you can even get it started to begin with.
The Cliff Notes on your Bing might look something like this: 1. Make sure the carb is super clean inside and out and has has all mounting/mating surfaces smooth and shiny. 2. Use all new gaskets. 3. Make sure all jets are free of any type of blockage. 4. Make sure your slide pot jet needle is smooth and shiny where it seats in the jet. 5. Make sure the jet needle is clipped at position 2 (from the top). 6. When adjusting, start with a higher idle speed and turn the idle air screw in until engine revs begin to decrease. Turn back out until the engine comes back to normal idle. 7. Check your choke piston and make sure it's making a good seal. 8. Make sure you have the start and idle jets installed in their correct positions. 9. Make all adjustments only when the engine is good and warmed up.
To throw you one final curve, if you continue to have performance issues after trying the above suggestions, like smooth acceleration, don't rule out timing, your spark plug, condition of your points, etc. Your carb is only one part of the equation. Don't 86 it until you know all the bases have been covered.
CHASSIS
Personally speaking, the restoration of the Isetta chassis is one of the most gratifying parts of the whole project. It's also the messiest. Consider the fact that everything has been under the car for 40+ years and is plenty filthy by now, especially the steering knuckles, chain drive, engine and transmission. You can also bet that those brakes are shot too, particularly the wheel and master cylinders. Their innards have accumulated water over time and are probably rusted, or almost rusted, in place. There are some early before-and-after shots of our car's chassis posted on the Isetta Source site if you care to take a look at a fairly typical unrestored mess and what you can expect to get in return for your efforts.
There is no substitute for complete dismantling of the chassis and all of its subsystems if you're going the frame-off route. Once you have it down to a bare, and we mean BARE, frame you can have a nice powder coat job put on it and begin reassembling all of the original components that have either been cleaned up or replaced. All rubber items should be tossed in favor of new ones. You're well advised to replace all wheel bearings as well. These are $5.00-$10.00 items that can make a huge difference.
Rather than delve into each component here, please refer to the section of this page that is appropriate for the item(s) you are currently working on. For instance, if you go to the "Brakes" section, we will cover the disassembly, cleaning, rebuilding, reassembly and adjustment of same. Likewise with the chain drive, steering, suspension, etc.
Let's discuss the literal frame itself, though. This ladder-like backbone is one rigid unit. It's side rails are constructed of square steel tubing with round tubing at the front and rear. The second crossmember from the front is the rigid axle, also made of round tubing. The center crossmember is a U-shaped channel that the master cylinder bolts to on the driver's side. Finally, there are two curved steel tubes at the right rear that are your motor mount points and one at the rear in the middle of the frame that curves up and out with a t-shaped top bracket where the top of your rear shocks mount.
Once you have your frame void of any peripherals, you're ready to prep it for media blasting and paint or powder coat. In our opinion, go the powder coat route. You won't regret it. There is some minimal, but important, preparation you need to do before delivering it to your blasting/painting vendor.BR>
• Clean, even lightly hone, the kingpin holes and put a light coat of waterproof bearing grease in them prior to the next step. • Plug the top and bottom of your front stub axles. Do this by putting a washer on top and bottom of the kingpin hole that completely covers it. Use a long bolt and nut to secure them.
• Using the same method, plug the tube that houses your lateral steering shaft. This is the tube that extends from the steering gear box to the outside left front of your frame.
• While not a show stopper, go ahead and put a small nut and bolt in the top, inside hole in your front motor mount tube. That's where your engine-to-frame ground cable will attach on the frame side. You need a good, clean connection to the frame if you want your engine to start.
One rule of thumb to go by here. Round up EVERYTHING you want to have coated/painted. On a side note, don't rule out small stuff you may have around the house, too. Think it through before you back out of the driveway. It's a lot cheaper to have a lot of parts done at one time than go back and have to pay a minimum fee (usually $50.00 or more per color for powder coat)if you've overlooked something or change your mind. Here's a list of what you might want to deliver to your vendor:
• (1) Frame
• (2) Rear splash guards
• (1) Splash guard mounting bracket
• (1) Air cleaner canister (2 pieces)
• (1) Engine cooling shroud (3 pieces including heater flap)
• (3) Brake backing plates
• (5) Wheels
• (2) Shock towers
• (2) Coil springs
• (1) Tie rod
• Pedal linkage cover
Other candidates might include:
• Blower fan housing
• Blower fan housing ring
• Oil pan
• Seat
• Muffler
• Anything that can withstand 400 degrees for 30-45 minutes. No, your steering wheel is not a good choice.
D
DOOR
The door is a project all by itself. There are more parts and more details that come into play than meets the eye here. There are aligment issues, door seal, silentblocs for the instrument panel, door piston, upholstery, hinges, glass, bumper, windshield wiper motor grounding, lock and trim.
We're going to tackle this subject starting with the dismantling of the door and building it back up from bare-bones. We'll assume that you've already taken the instrument panel, steering column, door piston, door handle and inside latch, upholstery, rear view mirror and fresh air duct (if you have the Deluxe model) out and the door is hanging there by its two hinges. It might do you well to shoot the door handle/lock assembly and hinge pins ahead of time with a product such as PB Blaster and let it do its magic overnight. Some folks have had a bear of a time with rusted hinge pins, for what it's worth.
Removal
Take a putty knife and scrape that old, farkled door seal off. Werner and Hans both stock new ones for you ... about $35.00. You can take a case cutter with a new blade and slowly, carefully cut the seal around the windshield and pull the glass out. There's just enough room between the lip of the door and glass for that blade. Be sure to remove that old locking strip first. Go ahead and remove the stiker plate from the door frame and keep it with the latch.
Remove those old silentblocs in the door's instrument panel mounting bracket. You might find it easier to do with the door still on the car rather than laying on a work bench. Using a heat gun, you should be able to work them out. Do not use excessive force or you can bend the tabs the silentblocs are mounted in. It is highly recommended that you install your new silentblocs at this time. Trying to do this after you have a shiny new paint job on it can be risky in terms of scratching things up.
Examine the tubes on the left of the door where the hinges pass through. These represent the two stress points on your door, especially the lower one. You may find that yours have been welded or have had some sort of reinforcement put in place due to this very factor. In retrospect, we wish we had fabricated a small steel reinforcement plate for our car's bottom hinge but that's water under the bridge at this point. Check to make sure that your door closes all the way and that there is no binding or obvious stress around those hinges. If you do, be sure to point it out to your body shop and have it corrected. It would be a shame to get that door painted only to find you have a problem with fit and/or closing properly. If overlooked, it can be a very frustrating problem to attempt to correct.
Now, with the aid of an assistant, remove the e-clips from the bottom of each door pin, pop the pins out and lift the door away from the car. Might keep a heat gun and some PB Blaster rust desolver handy in case you have a stubborn set of pins.
Finally, be mindful of the lip that runs around the outisde of the door. It's fairly stout but transporting the door with weight on that lip can bend it ... one more task someone will have to deal with.
Door Seal
Once the door has been dipped blasted, painted and is ready to install, it can be mounted back on the car for installation of the new rubber seal, hinges, handles and windshield. The key to the door seal is to make sure that you have a good, clean surface and use some serious glue. You might find that your glass man will have this and either do it for you or supply you with what you need. We've had lousy luck with anything with a 3M label on it, by the way. Especially that yellow stuff.
The seal itself is actually two pieces. The top, and much longer portion, runs from the bottom of one side of the door, around the top and down to the bottom of the other side. It has right angle cuts on the bottom edges. The bottom seal runs across the bottom edge of the door and butts up to those two right angle cuts on either side. While most commercial grade glues set up fairly quickly, you can run a bead down the back side of the longer strip a couple of feet and carefully place it against the door. Cut your first right angle before you start. Have several pieces of masking tape cut and nearby so you can tape the seal in place. Do the next two feet and so on. Once you're all the way around the door, you can cut the second right angle before gluing the final foot or so into place. Do the same with the bottom part of the seal and close the door making note that the seal is centered all the way around. You'll still have time to make any slight adjustments. Close the door using the handle and lock it down tight leaving the masking tape in place. Let it sit overnight and let the adhesive cure. You should be able to remove that tape the next morning and have a nice installation to show for it.
Door Hinge Rubber Seals
After that new door seal is in place, you can put your new door hinge rubber seals on and install the hinges. The repro seals we've seen are made by Metro Molded Products in Minneapolis, are of very good quality and are available in the correct gray factory color. Those rubber seals have caused some confusion as to what-goes-where. The two larger diameter seals belong to the bottom hinge. You'll notice that one is sightly larger than the other and has a bit more of an angle at its base. That's the one that mounts to the body, the smaller one to the door. You'll know if you got them installed backwards because the flat base of the seals won't fit flush with the door surface.
The two top seals will be obviously smaller. The cone shaped seal mounts to the door and the elongated seal with one flat side mounts to the body with the flat side resting against the window drip molding. Snug those seals down around the bolt tubes in the body and door for a good, tight fit. Avoid using any type of sealant here. It's not necessary and might damage your paint. Insert your hinges after you've given them a thin coat of waterproof bearing grease and hand tighten them. With the help of an associate, have your greased hinge pins handy and fit the door to the body. Now you can pop those pins in. Leave the e-clips off for now. By the way, if you're pins are badly corroded, look into a new pair of stainless steel pins and e-clips through parts suppliers. The pair go for about $20 and are very sharp.
Door Alignment
OK, you have your door painted, door and hinge seals installed and the door is back on the car. Now you can install the door handle/lock assembly on the interior side of the door, the striker plate to the inside tube frame on the passenger side, insert the door handles and make sure the hinge nuts are good and tight. Once this is done, you'll have your reference point for aligning the door. The goal here is twofold: Make sure the door closes flush with the tube frame all around and that the door lock closes just inside the edge of the striker plate without hitting it.
If you close your door and the "jaw" part of the door lock hits the striker plate, it's obviously too far to the right and needs to come back to the left a bit. This is accomplished with small aluminum shims that fit around the threaded part of your hinges. No two Isettas are necessarily alike. Some used no shims, some have shims on the bottom only, some on the top, combination of different shim thickness, etc. If you find that your door is too far to the right, placing a shim(s) between the body and the body hinge base will push your door slightly out or to the left, just what you want it to do. If you need to push the door to the right, you'll want your shim(s) to be between the door and base of the door hinge. That will push your door to the right. Play with this until you get it the way you want it. With two people to handle removing and installing the door, it doesn't take long to dial the alignment in. Once you're done, you're done.
Door Piston
This simple looking guy can pose quite a challenge. The door piston's primary job is to assist in opening the rather heavy door and, hopefully, keep it in the open position. As many of you have found, the inner spring has lost its oomph over the years and, while still useful in getting that door open, it also tends to let the door close on its own as well.
The piston has six parts: the inner and outer piston housings, coil spring, threaded retaining collar and two silentbloc/bushings. Replace those silentblocs while you have everything apart. If you order these, get six of them. These units are the same ones used in the drag link that connects the front of the chain drive to the rear of the frame. The other two cushion the rear of the instrument panel where it is bolted to the door.
The real issue here is that spring. First, if you take your piston apart, it is advised that you have an assistant to help steady the two parts of the piston housings once you unscrew the threaded collar. The spring compressor you used for the front spring tower/shock absorber removal is perfect for this job. Just place the piston in the compressor, crank it down until you can unscrew the collar and then back the compressor off until everything comes apart. You may want to shoot the threads around that collar with PB Blaster and use a heat gun to loosen things up a bit. Don't let that weak spring fool you! This thing packs a wallop and can turn into an unguided missile and do some serious damage if you're not careful.
There are several routes you can take in beefing your piston up. You can insert three 1/4" x 1 1/2" washers/spacers in the large end of the piston. This will slightly compress the spring to boost its lifting power but is not an eternal fix. You can add a gas strut inside the spring for additional boost, too. The cleanest approach we've seen so far is to order a new gas strut from Werner Schwark at Isettas-R-Us and eliminate that spring all together. The strut also eliminates all of that grease that goes along with the spring and saves a bit of weight, too. Werner has come up with the perfect setup that includes the washers that are threaded on at either end of the strut. It drops right into the piston housings, is smooth as silk and no assistant is needed to install it. Expect to pay in the $60.00 range for this unit.
Bubba Mace made one observation that you might make note of here. One of his housings had what appeared to be a thick wire soldered/welded into it which prevented his new strut from installing properly. Make sure the innards of your door piston are clean and clear from obstructions before proceeding.
One final detail on that piston. It may not dawn on you at first but be sure that the threaded collar securing both halves is screwed down as far as it will go. Why? Because that limits the piston travel when the door opens. If you leave that collar a few threads short, the piston will extend a bit farther and the door bumper will hit the left nerf bumper when the door is open. That's why.
DRIVE COUPLINGS
The Isetta's Achilles Heel. They are also referred to as donuts and guibos (pronounced "gwee-boze"). These poor things twist around in a continous S-shape while moving up and down with the chain drive. You can see from this pic that they sit at a contorted angle when they're not moving. Spin 'em up, move 'em up and down and you've got a lot of stress going on. If you do nothing else, make sure that you a.) have a good set of couplings, b.) have the correct low-profile coupling bolts with the lock nuts facing the inside of the car, not on the transmission and chain drive sides and c.) have them good and tight and check them on a regular basis. At around $80.00 for a new pair, it's a bargain compared to the holocaust you'll have on your hands if an old one decides to buy the ranch on you.
Craig Vechorik installed a pair of couplings for a BMW 325 automatic transmission model on his daily-driver back in the early '90's. Isetta parts were hard to find so he went with the real thing as opposed to the shoddy third party units that were available at the time. Here's a pic comparing the Isetta coupler and the 325 unit. The beefier 325 coupler is part number 26 11 1 225 624 and retails for $57.50 each.
Hopefully, Jim Janacek, Isetta guru and cameraman deluxe, will shoot some footage of the drive couplings under power. He brought the subject up at the 2002 National Microcar & Minicar Meet. We hope he can find the time for it in the future. It would be interesting to watch the action.
Here's some more drive coupling input from our friend Richard Lewis:
If you have inspected the coupling flanges and intermediate shaft and found that some of the ears are tweaked, the parts should be replaced or repaired before you install new couplings and the special thin head bolts. Since the couplings already run at a slight angle, it is important to have the coupling mounting ears running true. This can be done by machine shops or drive shaft repair shops.
DYNASTART
To many, this is a mysterious device. In reality, it's a big electromagnet and a good one at that. The Dynastart unit in your Isetta was manufactured by Bosch in Germany and carries their part number LA12-130-3R. There are many variations of this unit with part numbers varying slightly from the Isetta's number. One camp will tell you that these units interchange, i.e. the BMW 600 unit, part number LA-BM-12-130-3R, will fit the Isetta and vice versa. At face value, it would appear that some variations should bolt right on and work. The one's we've seen don't ... at least the BMW 600 unit. The round steel housing on that unit is deeper by a good inch or so and will not fit. You may stumble across another first cousin to the Isetta unit that is immediately noticeable in that the condenser is mounted next to the points. That unit won't fit either. We tried.
In a nutshell, the field coil housing has two staggered sets of coils, one larger group for starting and one smaller group for charging. This housing surrounds a heavy duty armature that is bolted to the outside end of the crankshaft. Starting the car is completely silent as there are no gears, springs or belts involved in the process. The voltage regulator sits in between the Dynastart and battery and monitors voltage levels during operation. A red light on the instrument panel tells the driver that the unit is in "charge" mode when the light comes on and in "battery power" mode when the light goes off. In an Isetta, if the red light comes on, that's good. When it goes off, that's good too. If it stays on, that's not good.
Here are a few things to watch out for on your Dynastart unit. First, many Isettas had their voltage regulators replaced, some with the correct Bosch or Noris units, some without. Many literally got their wires crossed and fried the leads from the regulator into the Dynastart field coils, the blue wire seeming to hold the record in this category. Cold or cracked solder joints where there is an electrical connection is another thing to look out for. This would primarily manifest itself where the coils are joined inside the field housing unit and at about 11:00 o'clock on the outside of the housing where your large yellow wire is fastened to a flat copper lead coming from the starting coils. While easily fixed, these can be hairline cracks that only rear their ugly heads once the engine heat rises or vibration breaks their connection.
While pretty bullet-proof, the armature can develop a dead spot and cause starting problems. We took ours to an automotive starter/alternator company and had them give it a once over with their growler. A growler is a device that looks for dead spots or grounds. As it is run over the surface of the armature, it should get a zero current reading if the armature is in tact. If it shows a positive reading, that tells you that there is a bad ground in the armature and a signal to get out your checkbook.
E
ELECTRICAL SYSTEM
Overview
Any vintage automotive electrical system can be a real challenge, especially if it's been partialy burned up due to modifications that got ugly or a voltage regulator that went into fricasse mode. Just about every tatooed Isetta wiring harness we've seen had ignition problems of some form or fashion with the blue and green ignition wires vying for first place in the Meltdown Category. One of the prior owners of our car went so far as to put a 25 amp fuse (8 amp being normal) on the ignition circuit and apparently turned the car into a space heater for a few seconds. Another mod was the installation of a Radio Shack buzzer on the turn signal circuitry. It appeared that the individual(s) that orchestrated this upgrade took the "I wonder if it's this one? No, I'll bet it's THIS one" approach to wire splicing.
The Isetta wiring harness is divided into four parts, 1.) Instrument panel to Terminal Block 1 (mounted on the driver's side wheel well), 2.) Main harness from Terminal Block 1 to the rear of the car, terminating partially at Terminal Block 2 mounted on the firewall and on up the passenger side to the headlight and turn signal, 3.) Rear harness from Terminal Block 2 on out to the tailights and, 4.) Ignition harness which only has four wires and runs to your coil and Dynastart.
At best, your harness is probably filthy, some of the shrink tubing may be frayed or gone. Extra wiring may have been added as a work-around fix at some point in time. Before you begin dismantling anything, get a #2 pencil and piece of paper and diagram your wiring harness for future reference. Taking one harness at a time, carefully strip that covering off and give it a good warm, soapy bath. It has been noted that BMW was rather stingy with their wire so make sure that you keep everything in its original configuration (lengths) if you removed that old covering. You can placed a tie wrap around the wires so they stay put.
An old tooth brush will help knock all of the crud loose. Dry the harness off and recover it with some new, fresh shrink tubing. When you buy heat shrink tubing, consider that the off-the-shelf variety shrinks two-to-one. If it starts out as 3/4" tubing, it can shrink down to 3/8". Our car had barbequed ignition wiring which followed a path from the Dynastart, up the main harness and on up to the instrument panel. If you have the classic toasted blue and/or green wiring, just replace it with 14 guage stranded copper wire from your hardware store and you're done. Keep the colors the same so it matches with the published factory wiring diagram.
Brand new harnesses are available from both Isettas-R-Us and Hans Rothkegel and are faithful to the original color codes. For what it's worth, the new instrument panel harness we bought was wired backwards. In another words, the shortest wire on the factory harness was the longest wire on the repro harness. Thankfully, the new harness had a generous amount of wire in terms of length and hooked up with no problem.
Color Codes & Wiring Schematic
Isetta Tech would like to thank Mr. John Jensen for his generosity and permission to share his electrical schematic with the Isetta community via the Internet! With the exception of a few minor tweaks in appearance, the schematic that is linked here is the same one that is published in John's book "Isetta Restoration - A Guide For Restoring The BMW Isetta 300 US Export Sliding Window Model" on page 158. The color codes, found on page 157, are public domain. The schematic is copyrighted material and is used here with his permission.
John told us, as he mentioned in his book, that this schematic was one that matched his 1958 Isetta and may not be 100% accurate for all year models. This diagram matched our early 1957 Sliding Window Coupe 100%! The only deviation from this diagram on our car was the installation of a European rear center light. The simple wiring procedure for Euro light is discussed in this section under Wiring Up Your Lights and is not depicted in Mr. Jensen's diagram.
Here's the color code chart. Here's the wiring schematic.
Instrument Panel Wiring
This isn't the nightmare that it may appear to be. While the area under that panel is somewhat restricted, you'll find that there's plenty of room for everything. This is another one of those jobs that just requires taking things in the proper sequence to ensure success and minimal hassle.
More info coming soon.
Turn Signal Switch Wiring
You'll probably find that the turn signal switch wiring is going to be the most tedious part of installing job. There are a total of six wires, three top and three bottom, that connect to the switch. All six wires must exit the bottom of the housing without getting pinched by the part of the switch that rests against the steering column. You'll want to cover these wires with shrink tubing. So everything needs to a.) be hooked up correctly and, b.) be the correct length before you crank up your heat gun.
When it really comes right down to it, the top three wires on the turn signal switch are the ones you have to deal with as the bottom wires fall below the part of the switch that rests against that steering housing. Just connect everything and pull those top three wires down each side of the recess in the switch where they meet up with their bottom three buddies. Test your turn signals and headlights before you put the heat on that shrink tubing! Please don't get it all gussied up just to find out that you got your signals backwards. Also, when wiring up the top and bottom of the switch, remember that the switch levers point up, not down.
Just for the record, here's how you wire these dudes up, starting with your high/low beam switch: Top (two brass terminals, looking at it from the lever side, lever pointing up): Right terminal=White, Left terminal=Yellow. Bottom (single terminal): Yellow and White.
Turn signals go something like this. (Again, looking at the lever side, lever pointing up): Top: Rear terminal=Yellow and Blue. Right front terminal=Black and White. Left front terminal=Green and Black. Bottom: Rear terminal=Red and Black. Right front terminal=Green, Black and White. Left front terminal=Red, Black and White. Isetta guru Jim Janecek supplied us with these top and bottom shots for your viewing pleasure. Here's how the top should look. Here's the bottom. Speaking of viewing pleasure, why not take a break, crank up the volume and go for a 50 mph cruise with Jim in "The Peril Pod"!
Check the functionality of this before you clamp the housings to the steering column. If for any reason it's not right, you're not going to burn the garage down and probably won't blow any fuses ... it just won't work or you'll have the sides reversed. And don't forget, if the turn signals don't work correctly, don't blame the switches ... yet. The lights at the other end must be correctly wired for the circuit(s) to work. Troubleshooting can be as simple as making sure that the bayonet-style bulbs are firmy seated, checking for reversed wires and/or bad ground(s). Taking a breather from a snafu has fixed a lot of problems too.
Finally, let's take a look at the Bosch flasher like the one originally installed in the Isetta. Its current part number is 0 336 102 022. The box will also indicate its electrical rating as "12V (1+1)x18W". Isetta parts suppliers are rather proud of this little guy in that the going price is over $30.00. Frankly, you can jet over to Auto Zone or your local parts house and get one of their three-pole units for around $4.00. One flasher that's guaranteed to work fine is the Tridon F550 12 volt unit. It will probably be marked "Max 4 lights" as well. Some offer an "extra loud" flasher for an extra buck or two. Get the loudest one you can get your hands on. You may not know it yet but you'll need one. It's virtually impossible to hear it over the exhaust system so you tend to drive around town with one of your turn signals on and not realize it.
As far as correctly wiring your flasher up goes, your looking for terminals marked X (power on), L (load) and P (indicator light). No one at the parts store seems to know this. You'll connect your power lead (circuit 76, blue and yellow) from the fuse box to the X terminal of the flasher. Next, connect the short red and yellow (circuit 77) lead to your instrument panel indicator light on one end and the P terminal on the flasher end. Finally, connect the blue and yellow wire (circuit 78) to the flasher's L terminal and the top, rear terminal on turn signal switch on the opposite end. That should do it. You can always refer to the section on wiring your turn signals a few paragraphs above this one for visual clarification.
On a final note, if you go the Bosch route, you'll find the terminals marked 49, 49a and C. Based on the Tridon description above, 49 is 'power on' or X, 49a is 'load' or L and C is 'indicator light' or P. There's a small wiring diagram in German that's included with the unit.
Wiring Up Your Lights
In this section, we'll cover the headlights, turn signals, tail/brake lights, license plate light, Euro center light 'upgrade' and instrument panel. We'll address details about each lighting component that aren't obvious and don't jump off of the schematic at you. In most instances, there are pix linked to augment the text. We're gonna leave the actual wiring job up to you, armed with your trusty diagram and color code chart.
The headlights are standard-issue 7" sealed beam units that can be picked up at any auto parts store. Basic lights are under $10.00 apiece with the newer, and preferrable, halogen units ranging from $14.00 to $20.00 per copy. Check out the "Headlights" section for the inside dope.
Your headlight wiring harness/plug assembly will snap right onto the back of your new lights and the stops on the inside of the headlight rings will fit perfectly into the corresponding glass 'bumps' on the outer back side perimeter of the lights to keep them centered once you've popped 'em back in the buckets.
The bullet-shaped front parking light/turn signals have three wires connected to each one of them. The tan wire connects to the outer grounding ring and is held on by the large nut that secures the bulb holder/reflector assembly. The other two wires are secured by screws in the bulb holder base. One provides direct power for the light, the other comes from the flasher for turn signal action.
The tail lights are just about as simple as the turn signals. The rear wiring harness makes its first stop at the right rear light. The reason we mention it is that you will have more than one wire connected to a given terminal, most notably the ground (tan) wires which continue on the the license plate light and end the journey at the left rear light as a single wire. If you should get everything wired up, turn your lights on and notice that one tail light is brighter than the other, you have the two hot wires on the brighter light backwards. One light thinks it's in "brake light" mode and the other is normal. Reversing those two hot wire should put that to bed. The rear bulbs are the same bayonet-type as the turn signal bulbs except they are clear as opposed to amber (assuming you don't have amber bullets in front with clear lights installed).
The license plate light is a European "festoon" lamp that is a cylindrical job with pointed contacts on either end. It simply snaps into its holder, gets a ground wires (41, tan) on one side and a hot wire (44, red and white) on the other. Doesn't matter which which color goes to which side.
While a tad off of the subject, you may find that the clear plastic lens for your license plate light has clouded up, cracked or is missing all together. You can fashion a new one with a small piece of plexiglass cut 1" x 3". Just drill two small holes in either end and get yourself a couple of small stainless steel self-tapping screws and spring/lock washers. That's about all there is to it.
The European-style center light was factory installed to meet the Euro safety standards, clearly 25 years ahead of the United States. US Export models had only a license plate light and a blank steel plate where the Euro light was mounted. This option can be purchased from suppliers as an upgrade for around $30.00 and is a good choice in our humble opinion. Wiring it up is a piece of cake. All you need is one wire running from either tail light (we recommend the left side, circuit 46) back to one side of your new light. Considering the fact that you already have a ground wire connected to the license plate light just below it, all you have to do it make a short jumper wire to the other side of the center light and you're done.
Here's one minor detail about that center light you might want to know. The standard festoon lamps you'll find in auto parts stores are the single filament variety, not multi-filament like your tail lights. What does that mean to you? It means that the center light is either on or off and will not get brighter when the brake lights are activated. If someone knows of a multi-filament lamp, please let us know the manufacturer and part number so we can post it here. A third brake light would be nice just for the price of a single bulb, and that ain't much.
The instrument panel lights are down right cool. Total simplicity in design and function. There are only four small lights here. The oddball is the speedo lamp that is a suppository shaped bulb and fits into the brass base of the speedo light fitting and glows a sort of sexy yellow. The other three, a psychedelic purple high beam indicator on the left, 7-Up-bottle-green turn signal indicator in the lower middle and red generator light on the right, complete the Isetta's lighting compliment. These are tiny bulbs, much smaller than the one used in your speedo. The link to the pic listed above gives you a pretty good idea of what you'll see but nothing compares to the real thing.
Ignition Wiring
The ignition wiring harness consists of four wires, three of which go to the Dynastart and one that connects to the coil. The green wire (circuit 90) goes to the postive side of the coil. The blue wire (circuit 91) along with the black and red wire (circuit 92) both go to the Dynastart and the black wire (circuit 93) runs from the negative (condenser) side of the coil to the Dynastart.
When we refurbed our harness, the ignition wires were separated from the main harness and got fresh shrink tubing. It seemed easier to isolate these wires for future troubleshooting or repair should the Dynastart or voltage regulator ever cause a problem. We've seen more than one original Isetta harness and they all seem to have had problems in the ignition department, never with the lighting. If any of the lights should ever develop a problem, you'll most likely blow a fuse. If your ignition system ever goes fubar on you, the damage can be much, much worse.
If you take a look at the pic of the ignition wiring harness link at the beginning of this section, you'll notice the spade connectors that were added to our setup. By doing it this way, you can simply unplug the Dynastart for service and forego having to ever remove wiring from under the seat. It's your call on this one but it certainly works well and looks good to boot.
The other component of this system is the thick cable that runs from the A (or 30h) terminal of the voltage regulator to the Dynastart post. We soldered a large round terminal, large enough to accept a 6mm bolt, on the post end of this cable rather than leave the stranded copper wire. There is a hole drilled in the post that the stranded end passes through and is then secured by a bolt threaded in from the top. We chose to mount our cable, with terminal, on the top of the post. We'll see how it stands up to vibration over time and report our findings should this turn out to be a not-so-great idea. For what it's worth, BMW made this change on the 600.
F
FRAME (See Chassis)
FUEL TAP
Given that the Isetta has no fuel guage, it relies on the fuel tap for switching to the remaining .8 gallons of gas in the tank once the engine begins to sputter. Assuming you have a full tank of gas, NORMAL position for your the fuel tap lever is to the right, or passenger side. The RESERVE position is to the left and, when centered, the tap shuts the fuel supply to the carburetor OFF. This tap has been the scourge of many owners due to its penchant to leak. There is a cork seal in the threaded collar that screws on to the tank. There should also be a seal or O-ring in the threaded collar that secures the fuel outlet nipple as well. One other source for potential leaks is the fuel line. We used two feet of Bing's alcohol-proof line. This line really seals well and doesn't require any clamps. It's also clear so you always have a visual for fuel flow, air bubbles/pockets, etc. You can even dress that engine compartment up and go with some of their clear blue line, too. At less than $2.00 a foot, it's highly recommended.
Probably the single biggest "leaker" is the tap itself. BMW used cork seals in the construction of this device and that old stuff is long since shot. At some point, a previous owner of our car just pulled the whole thing off, silver soldered a brass nipple in its place and sealed it with what appeared to be the world's largest glob of black Dubble-Bubble chewing gum ... very nice. Unlike your Bing carburetor, you can buy rebuilt, original taps outright although it's less expensive to have your existing one rebuilt. Parts suppliers can fix you up with a rebuilt tap or you can send yours off and have it done professionally. Craig Vechorik, owner of Bench Mark Works in Sturgis, Mississippi, can handle this task for you. See the Services Section for contact info.
The tap lever will require some behavior modification on your part. Many Isetta owners fail to turn the tap to the OFF position when they stop their car only to come into the garage the next morning to the smell of gasoline. Your Bing carburetor is not going to help you here. You must turn the fuel supply off to restrict any gasoline from flowing into your carburetor when not in use.
On a final, related item, be very mindful of the route your fuel line takes from the bottom of the fuel tap to the inlet on your carb. Keeping in mind that the Isetta employs a "gravity fuel pump", you'll want that line to be as short as possible and running downhill the whole way. It doesn't take much of an uphill kink in it to foul up your fuel flow to the carb. Leave just a little slack to allow for the vibration of the engine. Our line exits the fuel tank nipple in a line towards the carb, in front of the right rear mud guard, over the top of the mud guard/air cleaner canister bracket and on down to the carb. The carb's fuel inlet nipple is tilted slightly upward. So far, so good.
G
GAS
Unleaded regular.
GAS CAP
Now here's an exciting subject! Our car came with a locking BMW gas cap with no keys. Nobody was able to open it. Since it was in pretty sad shape anyway, the lock cover was cut off and guts removed. A new repro cap came from Werner Schwark and fits perfectly. The repro differs from the original in a couple of ways. One, it is all black with the BMW logo in the center. The original, non-locking cap, had the black, white and blue BMW roundel in the center and was very sharp looking. Second, under the top side of the cap, the original had a small piece of metal attached just under the ventilation hole in the center of the cap. This kept gasoline from splashing out of the cap and onto the paint. These sort-of-repros do not have this small, but important, detail. If someone out there can offer up a safe, effective solution, please let us know and we'll update everyone on the matter.
If you want something a little different, Bill Darland has mentioned that a John Deere riding lawn mower gas cap, with built-in gas guage, works like a champ. Might be fun to call the parts department at a JD dealer and ask for one of a gas cap for an Isetta and listen to the ensuing hilarity.
GAS TANK
Note: Our thanks to Isetta owner Richard Lewis for submitting the following information.
Isetta gas tanks can have rust problems. If you rebuild your carb and don't check the tank for rust, you could undo much of your hard cleanup work on the carb when you open the tank valve and pour tiny rust particles down into the little fuel filter bowl. A source for gas tank restorations is Mattson's Radiator in Stanton, Ca http://www.mattsonsradiator.com/) they are familiar with Isetta gas tanks and will charge between $89.95 and $129.95 for a tank restoration. The price will vary depending on the tank condition and if you need the exterior finished also.
If you want to save money and can refinish the exterior yourself then the interior can be treated with Kreem fuel tank cleaner (2 part) and liner. The liner product will seal the tank and even take care of small leaks. Kreem is available at motorcycle shops or via mail order for about $30. If you want to pre-clean out a rusty tank before you use the Kreem cleaner and liner product, pour in strong TSP solution and about a cup of BBs or small ball bearings and shake the tank vigorously. This should knock off the loose rust flakes. After the second or third repetition of the TSP/BB bath you should notice the rust is almost all broken loose and the rinse water is clean. Note that the gas tank filler actually protrudes slightly down into the tank making it hard to get the BBs and TSP solution back out through that opening. Drain these out via the bottom tank outlet. A few minutes of tipping the tank back and forth will remove any fluid and BBs.
H
HEADLIGHTS
Yes, you can still buy 7" sealed beam headlights. Here's a great way to upgrade a very important part of your Isetta. Sylvania, among others, has several different 7" halogen lights, one of which is their Cool Blue series. These burn brighter than a conventional sealed beam unit but aren't literally blue. Auto Zone also has their own brand that is more of a blue if you want that European look and stay street-legal in the process.
Expect to pay in the $12.00-$18.00 apiece range depending on the model you get. More money, more light, more blue. Yep, the connectors on the back are ready to plug and play. Just place the new light in your headlight ring, pop in four or five retaining clips, plug it in and secure it to the headlight bucket. Legal in all 50 states too. See Sylvania's Web site for product info then visit your local auto parts dealer and snap a couple up.
HEADLIGHTS, AIMING
To properly aim your headlights, park your car on a flat surface. The front of the headlights should be 16 feet and 4 inches from the wall you'll be shining your lights on. Mark two spots, left and right, 25 3/4 inches from center and 30 5/8 inches up from the ground. You can use magic marker dots on the wall, pieces of tape, thumb tacks, wads of Dubble Bubble chewing gum, .45 caliber bullet holes, etc. for your targets. Those are the spots that your bright lights should center on. Adjust those brights by loosening the hollow bolts that hold the headlight buckets to the car and center the beam on your target. Tighten them down and switch to low beam. You should see the brightest part of the beam shift slightly lower and to the right.
Here's an early drawing that depicts the metric distances required for proper alignment.
HEATER
The Isetta heater's effectiveness has been described as that of "a dog's breath". Most cars have deteriorated (or missing) paper hoses and cardboard heater covers on the under-seat unit and a shot rubber air hose connecting the engine cooling shroud to the heater input 'can' on the rear of the firewall. The original heater flap knobs are, for the most part, gone and/or replaced with whatever would fit. Ours had a trendy red kitchen drawer knob mounted on it.
If you have the core components of your heater, it's another cool project to jump in to. It's simple enough to have the under-seat heater unit, firewall can, diverter flap adjusting lever and windshield vent media blasted and repainted. The factory color used on heater components was silver. Items you'll have to deal with are as follows:
• Heater output hose
• Rubber hose from engine cooling shroud to firewall can
• Cover for underseat heater unit
• Small items such as the diverter flap knob and grommets
For lack of a better description, the original heater output hose was an aluminized paper material which time took its toll on. All but four inches of ours was gone. This hose was also the haven for small creatures that found their way into primarily garaged Isettas. Several skeletal remains have been reported by owners during the dismantling process.
New heater output hoses are readily available from suppliers. Isettas-R-Us offers a truly sharp hose that will compliment any interior with its textured fabric-like tan finish. You can also go to JC Whitney for their fresh air vent hose that resembles a slinky toy covered in black plastic. You'll want the 1 3/4" variety. The only downside to the JCW hose that we found is in the area that the hose has to pass behind the shift lever. It's just enough 'fat' that the shifter doesn't seem to have enough room to smoothly move in the third and fourth gear plane. It's tight any way you cut it. Werner gets $15.00 for his hose and JCW gets $20.00 if that matters.
One other hose-related item to consider is one-piece versus two-pieces. The only real issue at hand it where the hose passes behind the left side seat frame in front of your spare tire. If the seat is adjusted all the way to the rear, you'll probably pinch that hose and restrict an already wimpy air flow. That's where the two-piece approach comes into play. Werner sells his hoses in this fashion and for that reason. What's not included is a coupler. Keeping in mind that you're dealing with a 1 3/4" diameter hose, you can fashion one from a short piece of PCV pipe or snoop around the closet where your wife has the wrapping paper stashed. The cardboard roll in the center of the wrapping paper is darn near perfect. Cut a 6" section of it off, dry fit it to the hoses to make sure it's a good fit and then glue it into ONE hose. You can put a hose clamp on it and gently tighten it down to get max contact for the glue.
Make one of your hoses long enough to run from the heater output tube and over in front of the rear seat frame. Your other, longer hose will run from there, through the bottom rear of the driver's side panel and to the front, exiting in the side panel hole just under your windshield heater vent. Now, you have a quick disconnect under the seat should it have to be removed for maintenance purposes and you've circumnavigated the pinching problem associated with that one piece hose.
Werner has also taken the initiative to tool up a nice cooling shroud-to-firewall-can hose. Just a couple of stainless steel hose clamps from your hardware store and you've just knocked out one more problem. By the way, last time we looked, that hose ran around $65.00. Some owners have used that same flexible hose mentioned above, but a larger diameter, to keep costs down.
The cover for the heater unit can be a bit more of a project. The original was something like two rectangular cardboard trays with a raised lip around the edge, sorta the same form-factor that you get ground hamburger meat on at the grocery store. The top and bottom pieces were stapled together to cover the center section of the heater unit that is drilled full of ventilation holes. We've never figured out why the heater wasn't just solid, stamped sheet metal to begin with. Perhaps the expanded metal was easier to form in the manufacturing process. Who knows? Short of trying to duplicate the original covers, we did something different.
You know those windshield sun shields that are planted on folks' dashboards? That material is perfect for the job. We got the smallest one we could find for around $5.00. It looks like aluminum foil with a thin pad inside. You'll want to take the likes of a grocery sack and make a template to work from. The area where the heater unit curves around on the front passenger side and corresponding back side is the part you need to practice on. Once that template is done, just transfer it to your sun shield and mark it off. Deliberately cut it a bit on the large side so you can trim it up nice and neat. Grab a roll of aluminum tape to fasten the seams and you're done. Looks pretty cool for something nobody will ever see.
Now to the small items. To the best of our knowledge, that knob that fits on the end of the long skinny flap lever (the one that pokes out from under the seat) is not a readily available item. We found one in a VW/BMW/Audi junk yard on an old VW bus. We had to buy the whole turn signal assembly since that knob was glued on tight and wouldn't budge. We finally got it off, cleaned it up and painted it with Krylon Appliance Epoxy (see Steering Wheel section). Looks great and is the same look and feel of those bullet shaped high/low beam light and turn signal knobs on your steering column. By the way, if you get real lucky, the same basic knobs were used on the BMW 1600. Those knobs use a 4mm thread so you'll have to re-tap them for 5mm to fit.
One other potential challenge are the two grommets that the heater flap rotates in. These dudes are made of layers of cardboard and may be flaking apart, like a croissant, if not totally shot. If they're missing, you can get a couple of new ones in the plumbing section of your local hardware store. You'll have to make a cut on one side so it mounts flat against the flange where the heater vent mounts to the main unit. This keeps the grommet from turning. If you have your original grommets, just coat them with some epoxy and let it set up. That should do the job.
Finally, be sure to make a good seal to go between that firewall can and the firewall itself. You don't want any engine compartment fumes finding their way into the cockpit. Thick cardboard or 1/8" neoprene rubber stock will work here. Just use your heater can for a template to mark the outside diameter. Cut the inside diameter about 1/2" inside that and punch three holes with a standard-issue hole punch and your done.
Here are a couple of shots of the finished product right here and here.
HORN
Isetta horns were supplied from various OEM suppliers. Ours is an Artes unit from Barcelona, Spain. It was surprising clean inside given that it spent its whole life under the car. The horn mounts under the slanted portion of the front floorboard via steel bracket and is angled down and slightly forward when secured. Two wires descend through the floorboard just behind you steel tube door frame, one tan (ground) and one green and white (hot). If your horn wire posts are threaded with nuts and lock washer, be sure and solder a round terminal on each of those wires and make sure that big honker doesn't lose its connection.
Speaking of connections, or lack thereof, here's a problem we had and the solution to it. As previously mentioned, our horn worked when the car was dismantled. It didn't when we re-installed it three years later. Even though the horn circuitry is goofy to say the least, there was no doubt that everything had been restored properly. Just to be sure, we checked everything from the copper grounding ring on the horn button bezel for proper contact, the position of the carbon brush on the brass steering column ring, correct wiring ... you name it. It didn't work.
The fix? It was so seemingly insignifigant that we looked right at it and missed it the first three times. The horn has three basic subassemblies, the base, the center plate that the magnet contact mounts to on the bottom and resonator plate mounts to on the top and the chrome cover. The bottom of that center plate had a thin paper gasket on it that we thought was a seal. Part of it had deteriorated like an old piece of newpaper and fallen off. Turns out, that paper gasket is an insulator. It's absence creates a dead ground. Dead ground, no sound. We put some masking tape around the base unit and reinstalled everything. Bingo! You can either trim that tape up with an Exacto knife or make a neat insulator with new gasket material. Whichever route you go, just make sure it's there and your presence will be known when the occasion arises.
If your factory unit doesn't honk loud enough to relocate those four wheel drive Suburbans and Roadmaster Wagons into a bar ditch, you can check this Hella air-raid-duo out at Griot's Garage under the Accessories, Exterior tab or search on part number '77573' or 'hella'. These are mean looking little guys that are the same basic form factor as the original Isetta horn except you get two instead of one in this $70.00 package deal. Were talking 118dB here, just slightly less than a Motley Crue concert. Each horn is tuned to a different frequency (300Hz and 400Hz) so you're doin' it in stereo when you punch the button. The horns we've seen use a standard male spade lug connector. You'll need to put a couple of female connectors at the ends of your two horn wires and make a short pair of jumper wires to connect horn #2. They should also have female spade connectors. Just add a two-terminal spade connector to horn#1, connect your wires and your set to create some commotion. Griot's phone number is 800.345.5789 if you need further clarification on the matter.
If that's not good enough for you, check out The Auto Barn and search on "horn". The've got everything from 2 3/4" 100 dB units to the coveted Wolo Animal House 35 Sound Electronic horn. We're talking max entertainment with selectable animal sounds, 10 different sirens (hire a good lawyer before you use this feature), 16 musical selections and a built in PA system. This incite-a-riot unit is under $50.00, less than your public nuisance fines and court fees will be. You can also go for an off-the-shelf unit from the auto parts store if you're on a budget. You'll probably want a horn in the 4" diameter variety. Finally, you can also check with suppliers and keep that factory look/sound too. Original horns tend to be plentiful and reasonably priced. Whatever you do, use your horn prudently!
I
INTERIOR (also see Upholstery)
In this section, we'll discuss everything in the Isetta Sliding Window Coupe interior that is not upholstered. To read about your options and how to go about it, please refer to "Upholstery" farther down this page.
One third of the Isettas interior is the paint job. Make sure your body shop paints everything! If nothing else, you've just added more years to your car's condition by giving every square inch an extra layer or two of protection. Very small bits and pieces of the body will show once your car is back together so don't let your paint people cut any corners on this one. Make sure they paint the outer (larger) part of your door piston, the complete inside of the door, the sunroof frame, the engine access panel, your air plenum (if you have a Deluxe model) and of course, your instrument panel.
While a few of the following topics are covered in other sections, we'll mention them again for the sake of redunancy. Your sunroof frame can be bolted back in the car along with its handle and spacers. If nothing else, it will get the frame out of your way and keep it from getting scratched. Make sure that the front underside of this frame has some sort of temporary padding on it so it doesn't scratch the roof of your car.
One potentially pesky little part(s) are the clips that are riveted to the roof that hold the sunroof clips in place if you're only going to partially open the roof. The clips, along with your window latch striker plates, require the same small rivets to fasten them back in place if you want the job done right ... just like the factory did. If you removed the spring steel swing arms on your sunroof frame to have them chromed or painted separately, ditto for those two pieces. These rivets are not easy to find! Pop rivets aren't the answer either since they protrude out on one side. The closest thing we found, short of having to buy a whole new riveting system, were the type used to fasten brake lining on the brake shoes in that the rivet flattens out on each side. This will probably require you taking your car to a brake shop for a 90 second service call unless you can find someone who will let you borrow their gun for a little while. Good luck on that one ...
When riveting those window striker plates on, just make sure that the bottom of the plates are resting on the window sill ... as far down as they will go .. and that they are level. If done incorrectly, they can potentially have an effect on your window latch(es) ability to lock properly. That striker plate should be on the outside of the sill with the dog-eared part to the outside and front of the car. The "pretty" side of the rivet should be on the inside of the car as the other side will be covered up by your window channel felt once it's in place.
Once this is done, you can install your plastic window sill trim along the bottom. Make darn sure this is in place before you put your rear window rubber seals in. It's a very tight fit and attempting to do this after the fact could be a real wrestling match. You can also install your trim around the perimeter of the sun roof cutout. If you have those small sunroof clips riveted into the roof, just cut one piece of trim to fit between the two clips and run the rest from the outside of one clip, around the perimeter to the outside of the second clip for a neat, seamless job. Simple, effective and easy to put on.
Next, you might want to install your refurbished shift mechanism. This subassembly an interesting one and an easy job to clean up. More detail on the process is discussed in the "Shift Linkage" section. The following text assumes that your tube has the heater and choke levers installed, is lubed and ready to go. Feed that shift tube in from the inside of the car, through the hole in the left side of the firewall. Fasten the front down with three nuts and bolts. You'll need another person to get under the car to help you bolt the rear L-bracket onto the back, left side of the spare tire well. Now, you can fasten the rear of the tube to the bracket. We'll discuss the swivel and return spring on the rear of the shift tube in the "Shift Linkage" section as well. Make sure that both front and rear mounting points are good and tight. The shift linkage can tend to be sloppy on a good day so make sure that tube is secure. While your under the car, go ahead and install your rubber shift boot and secure the firewall (forward) side of it with a hose clamp.
If you haven't already done so, now would be a good time to install new rubber grommets in all pass-through holes in the firewall. These are off-the-shelf items your hardware store should have for you. You'll need a total of six. Five of them should be pretty much the same size and will accomdate the heater and choke cables as well as the three holes on the bottom of the passenger side where your wiring harness and starter cable exit. That sixth grommet, the one that's in the bottom of the spare tire well, is slightly larger as it must accomodate the thicker hand brake cable. The only other grommet on the firewall side is the one that fits inside a round steel cover where the speedo cable passes through to the engine compartment. The one on our car just needed a hot, soapy bath and was ready to to. This one might be more of a challenge to find due to its larger diameter.
Pass your heater and choke cables through the firewall. Hook the respective front loops around the outside of the control levers. Your shorter cable is for the heater and attaches to the longer, bottom lever. The longer cable is your choke cable and attaches to the the shorter, top lever. Slip the grommet around your speedo cable, pass its steel outer cover down the cable and feed the it through the firewall. You can now screw that outer cover down with two small sheet metal screws. Your handbrake cable should already be attached to the rear brake. Feed the front of that cable through the firewall into the cockpit and leave to one side for later installation on the hand brake mechanism.
One very nice detail is the addition of a new serial number plate. These can be ordered and stamped with the serial number and year-of-manufacture of your car. Place that new plate on the interior side of the right front wheel well. Pop rivet the two bottom holes first. It will become obvious that your new plate, being flat, will have its top holes slightly above the top holes in the wheel well. Simply take the rounded handle of a screw driver, cover it with a soft cloth, and gently press the plate into the lateral bead in the wheel well, just like the factory did. This will bring the top of the plate down a tad and should match up with the top holes. Now you can rivet the top of the plate in.
Your under-seat heater can be bolted in now. Nitty gritty details on refurbishing the heater are discussed in the section above by the same name. This is another two person job. Make sure you have a good seal between the can on the engine compartment side of the "can" that mounts against the firewall. Facing the heater inlet flange at the firewall on the inside of the car, start with the lower right bolt first. It's the tightest of the three. Don't tighten anything down until all three bolts are installed. Once the main unit is secured at the rear, you can fasten the L-bracket mount on the floor with two sheet metal screws. Your hose(s) will come later.
Your battery box comes next. That box should have two ears, one on each side, for securing the battery. Suppliers can fix you up with the threaded side rods and a new top strap. If you're in do-it-yourself mode, A couple of threaded rods, wing nuts and a steel strap could be made up to accomplish the same thing. Those rods will need to be bent at a right angle at the bottom where they pass through the ears on the battery box. One other item to be aware of is the height of the rods. Ours were way too long. In another words, they stood up too high, almost to the underneath side of the seat bottom. We shortened our by about half and cut new 5mm threads for the stainless steel wing nuts. It is advised to either have your battery handy to put in the car or at least know the height dimension before getting started on those side rods. To finish things up, we put a strip of 3M Safe Step on the bottom of our steel retaining strap to cushion the battery as well as a neoprene mat for the bottom of the battery box. This was cut from stock neoprene rubber sheet available at many hardware stores. Around these parts, it sells for $3.50 a foot in is approximately 13" wide.
Now your voltage regulator can be bolted in. If you're still running the original VR in your car, you'll have two threaded mounting plates just to the rear of the battery box. Be sure and use lock washers because it is here that your regulator grounds. Some folks have even made up a redundant ground cable from 14 gauge wire just to make sure. That wire can run anywhere a good ground to the body or frame. The battery ground cable that attaches to one of the terminals on the rear right side of the regulator (position varies dependent on manufacturer but it always attaches to terminal 30/51 aka 30/B+)should be long enough to loop around the battery on the driver's side and fasten to a 6mm stud directly in front of the battery box. We used a stainless steel wing nut and lock washer here for a good solid contact.
J
Work in progress.
K
KEYS
Your Isetta has three keys; ignition, door lock and engine cover. The cover key is a unique little guy, shaped like a thumb screw with a square end on it, but the same for all Isettas. Werner or Hans can supply one of these for around $10.00 plus postage. The ignition and door key can be made by any competent locksmith. The ignition blank is Taylor Lock Company number M73N. Your locksmith will need the key code number stamped on the face of the ignition switch where you insert the key. Should read something like "SH141". The door lock key is Taylor Lock Company number 62VB. The key code for the door lock can be found on the square shaft that the handles are attached to. Just take the inside nut off, slip the inside handle off and pull the assembly out from the front. You'll see the alphanumeric code on two sides of the shaft. It should be somewhat similar to the ignition key code but with the alpha part on one side, numeric part on another. The combined code should look something like GC7461. Go ahead and have a spare set or two made up while you're at it. Additional keys are cheap (insurance).
L
LIGHTS (See Electrical System)
M
Work in progress.
N
Work in progress.
O
OIL
There is no way we can write this up to everyone's satisfaction but we'll give it a try anyhow. Ask the next ten Isetta owners what they run in their car and you'll get ten different answers with a few footnotes thrown in. Viscosity, natural vs. synthetic, blah, blah, blah. The best advice we ever got was this. "You don't own a car. You own a motorcycle with a body wrapped around it. You gotta start thinking like that". This advice came from Perry Bushong, President and owner of BMW of Fort Worth. Perry has beaucoups experience with vintage BMW bikes and rebuilt our engine. Keeping in mind that we're in Central Texas where the summers get over 100 degrees and freezing weather is something that happens very few times in the winter, 20W50 motorcycle oil was the recommendation ... Belray, to be specific. Kendall was also touted but nobody we've asked knows where to get it in the Austin area. Other good competition motorcycle oil was also deemed acceptable, BMW included. Whatever you do, change your oil and air filter on a regular basis!
The transmission and chain drive run Belray 95W140 gear lube. This stuff, as the weight implies, is thick stuff, works well and is not prone to leak. A year and a half later, our car hasn't sprouted one drop of oil at either the trans or chain drive. If you're keeping score at home, the factory originally spec'ed 40W, engine included.
The final two units that get oil are your two steering knuckles. 40W was also the factory spec here. Just about everyone's seals have been worn out and that 40W has no place to go but out, all over the front suspension. Sure, new swing arm seals will solve that problem for a while but Perry came up with a much better idea. Instead of filling those steering knuckle reservoirs with 40W, pump 'em full of waterproof bearing grease. Not only are those swing arms lathered in lube but that grease ain't going anywhere. A nice touch, and the one that called our attention to this mod in the first place, is to drill a hole in the center of the filler caps and thread them for grease fittings. You'll want to use the angled type fitting so you can get a grease gun/hose to it for servicing at a later date. No leaks here yet either.
One interesting little thing you might want to do is to save a vial of your old motor oil and forward it to Petroleum Products Monitoring, Inc. for analysis. They’re located in Athens, Georgia. Call them at (800) 564-3132 or email them at ppminc@ppmoiltesting.com . You can also visit their Web site at www.ppmoiltesting.com and order a kit online. Only the Shadow knows what evil lurks in the heart of your engine. Now you can find out for yourself.
Contrary to what you've read, Isettas have oil filters ... you!
OIL PAN DRAIN PLUG
Although it's a small item, you might want to splurge on a magnetic drain plug for your pan. At under $7.00, it's an inexpensive way to get a visual check on what's living down there in your engine's oil supply. The original BMW part number (11-13-0-007-163) has been retired. The new part number is 11-13-1-744-329 and should retail for around $6.50 plus tax. Give your local BMW bike shop a buzz and see if they have 'em on the shelf. It may be a special order item so plan ahead.
P
PAINT
We learned a lot about automotive paint and the processes that are involved in applying it. And it ain't cheap either. Our cas was shot with a light, bright yellow base coat/clear coat finish. It's Glasurit number SY-045.5. Unfortunately, the Glasurit database cannot produce the vehicles this number was applied to at the factory, only how to mix it.
Without getting into the body shop part of the project too much, there are four different applications that go into a base coat/clear coat paint job. First, and probably the most important, is laying down a couple of coats of epoxy-based sealer on the bare, prepped metal. We had our car dipped, some have theirs media blasted. This sealer provides a hard shell around the metal and won't allow moisture to get to it. The most obvious reason is to keep rust from forming and another is to provide a base for any type of body filler that may be used to make those dents and dings disappear. Ever see body filler that's cracked? 10 to 1 you're looking at a car that never got properly sealed. Moisture got up under there and unraveld it from the back side.
The body work phase of the operation comes next. Once the filler has been applied, blocked and sanded, your car is ready for the second application, primer. With a good water-tight base to adhere to, the primer provides the surface for the color of your car. Many times, you'll see a body man spray black streaks all over the car. This gives him a baseline for the final blocking and sanding procedure and will show obvious low spots where the black paint is left in a given area.
Once the primer has been sanded and cleaned, it's show time. Your base coat paint dries to a satin patina, not shiny like you might think. Two coats usually do the job. Given that, our Isetta took about a quart and a half to paint ... less that we would have guessed. Given that this paint dries pretty quickly, the fourth and last application is the clear coat itself. That puts the gloss down. Once it's been buffed, you can put a coat of polish on it right away. Notice we said polish, not wax. Products such as Wizard's
Q
Work in progress.
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RUBBER PARTS AND SEALS
If your Isetta is like most, the rubber components are all shot, disintegrated and/or gone. Replacing these items will make a big difference in both performance and appearance. Let's go through the list and briefly discuss what you're looking for.
Exterior:
These pieces can usually be purchased separately or as a turnkey kit. The US Export Models were fitted with gray rubber while the Euro version was fitted with both gray and black. We chose black simply because of the yellow paint job. Although most pieces are available separately, we got the kit, manufactured by Metro Industries in Minneapolis. They make replacement rubber parts for all kinds of car, including the Isetta.
This kit includes rubber seals for the headlights, turn signals, door hinges, front nerf bumpers, driver's side rear view mirror, tailights, rear bumper/nerf bar and two seals for the rear air intake and license plate light pod. The pieces are of very good quality in terms of finish and fit.
We've were told by several knowledgable folks to refrain from using any kind of sealant, like silicone, with this rubber. The rubber will do the job all by itself if installed properly and you'll avoid ruining fresh paint too.
Other seals you'll need to buy separately include the front rubber seal for the sunroof. This is a unique item and can be sourced through Isettas-R-Us or Hans Rothkegel. A trim item worth noting is the welting that fits between the rear of the body and the rear bumper. It's a small item but really sets things off nicely when properly installed. You can either get these from suppliers in silver/gray or have your upholstery shop make some up for you. This is nothing more than vinyl material with a round plastic line running through it. The stitch is made right against the plastic line which produces a nice bead, the part you'll see once it's on the car. Have them make a three foot section just to be safe. You'll need to cut holes in either of the two scenarios and cut V-notches on the inside of the trim where it bends around the rear side of the car. For what its' worth, the shop charged us a whopping $5.00 to custom-make our welting.
Under Car:
Here's where everything will REALLY be a mess. Number one in just about everyone's book are those silentblocs in the tie rods, steering arm and left steering knuckle. They should be shot by now and are the number one contributor to the "Isetta Watusi" you may have heard about. That's the uncontrollable shimmy of the front tires at speed. All four silentblocs are be the same part number. The old ones press right out and the new ones press right back in with the use of a little heat from a propane torch or heat gun. One former Isetta owner noted that he blew off the silentblocs completely and had four bushings made from Delryn, a space age plastic that is just about indestructible. He said that the Delryn bushings also did away with any need for a steering damper as well. Check under "Plastics" in your Yellow Pages. You won't need much to have these made up. There's no need for an outer steel skirt but you'll need the center steel sleeve for a bolt guide.
In a tie for first are the drive coupling or donuts. BMW calls them guibos (pronounced 'gwee-boze'). Unless you know the age of these couplings, buy two new ones and make sure they are tightened down and stay that way. Suppliers have these for you at around $40.00 apiece.
Other items you'll want to consider replacing are those silentblocs in the cast aluminum drag link that connects the bottom front of the chain drive to the frame. Those things take a beating too and can sure help smooth out the ride. They're the same ones that fit the door instrument panel bracket and door piston, by the way.
Replace those seals at all four wheels too. The front uses O-rings at the swing arms and thicker round seals at the axles where they protrude through the brake backing plate. Your chain drive seals at the input flange will no doubt need replacing as well. You can obtain those individually or in a complete chain drive kit which includes all of your gaskets as well.
In the rear of your car, the rubber bushings at the bottom and top of the shock mounts are probably compressed and cracked. We got lucky and got a pair of left-over bushings from a muffler/shock shop, cut them in half and popped 'em right on. The bushings in the rear of the leaf springs should be pretty well fubar'ed too. You may need to tenderize them a bit by spraying some PB Blaster on them and letting it soak in to loosen any rust. Any hydraulic press can move these old timers on down the line for a fresh new pair. Have this done when you take those springs apart and have them blasted and painted. Makes a huge difference. See the "Springs" section for more on the subject.
Looking to the frame, you'll want to cut some 1/16" rubber pads where your body is bolted. There are two at the back, three on the axle crossmember. The middle pad is rectangular and the two on the sides are triangular. These can also be purchased as a kit but, in our humble opinion, they tend to be rather thick. That 1/16" rubber stock can be bought at many hardware stores by the foot. You don't need much. You can punch your holes very easily with a standard hole punch, too.
Additional rubber items include the two boots that seal off the clutch and accelerator cables where they pass through the front crossmember of the frame just behind where they attach to their respective levers behind the pedals. Kits can be purchased for rebuilding your master cylinder too and include that rubber accordian boot at the front of the cylinder. Werner Schwark has a nice repro heater hose that connects the input on the firewall to the cooling shroud. This is a one-of-a-kind hose in that is starts out square, makes a right downward turn and is round at the heater end. We've also seen simple flex hose used here with a couple of hose clamps if you're looking to save some bux and still have that heater hooked up. One more item you'll want to look in to is the accordian boot just behind the firewall that fits around the shift tube. This keeps noise and the environs out. It fastens to a round lip with a hose clamp on the firewall side.
S
SEAT BELTS
Perhaps "Splatter Reduction Devices" would be a better term, huh? While hardly a factory option, you might feel a lot better about having a good set of seat belts in your Isetta. We popped a set of Andover Restraints' standard 72" lap belts in our car. These guys look like they're right out of a commercial airliner with a simple chrome buckle and release. Expect to pay around $50.00 for the pair plus $5.00 for the mounting kits plus shipping.We had heard these were a pain to install but didn't find that to be the case. Three point belts would, no doubt, be more of a challenge but we're not convinced of that either. Just more work to install.
The mounting kits are nothing more than two very large washers with accompanying bolts, lock washers and nuts. An optional L-bracket can be ordered for a few bux but we didn't see any reason to go that route. Your going to have to drill 4 3/8" holes in your floorboard for those mounting bolts to go through. The two outside holes will be about halfway between the outside edge of the frame and the seam where the floorpan meets the curved side of the car's body. Be cautious and use a drift punch to make your pilot hole and then proceed with your larger bits.
The passenger side of the car is virtually unobstructed from underneath. You'll need to pay a bit more attention when you get over to the driver's side though. Specifically, make sure you're inside hole is far enough back to clear the brake light switch on the rear of your master cylinder and any brake lines back there. Second, the outside hole on the driver's side is going to be directly above the muffler. Take your time here and do it right. Because of the clearance between the muffler and floorpan, we inserted our bolts from the bottom of the car with the threads coming up into the interior. You could also make a run down to the hardware store and simply buy short bolts too.
Installation is about as simple as it gets. Just put your bolt through one of the washers and insert it from under the car. That washer is primarily for reinforcement of your floorpan on the underneath side. Slip the seat belt floor anchor over the bolt threads, drop a lock washer on and tighten the nut down. That's it. Be mindful of how the belt will look once it comes up and across the seat bottom. You may prefer to have the tags/stitching on the bottom for a neater look so check aspect out before you crank things down.
You can also get additional installation tips straight from Andover's Web site. This is the same info that will be packed in with your new set of belts. With all that having been said, we sincerely hope you never need them!
SHOCK ABSORBERS
The Isetta uses a different pair of shocks on the front and rear of the car. Both types are available through parts suppliers but stand advised that they are pricey ... and for no apparent reason. Your shocks can also be rebuilt.
The front shocks live underneath the triangle shaped shock tower and are the coil-over variety. The base of the shock had an eyelet that mounts into the front of the swing arm. If you're paying attention, you'll note that the eyelet is welded slightly off-center. Make sure that the offset side of the eyelet faces out when you install your shocks. Once you've bolted the swing arm end down, you can slip the coil over the shock making sure that they tighter coil windings are on the bottom. The stainless steel piston protruding out of the base of the shock should have three rubber donuts in place. These help absorb vibration when the shock is compressed.
Now is a good time to install a new pair of shock bumpers in your steering knuckles, too. Just pop the old rotted ones out and insert the new ones. Your shocks will push in on these bumpers when everything is back together. Before you install your shock towers,make sure that the piston is pulled up as far as it will go! Go ahead and put your shock towers over the coil/shock assembly and, using a spring compressor, crank each side down evenly until the top, threaded part of the piston is through the hole in the top of the tower. Now you can put the rubber grommet and washer on and secure both nuts. A front and rear nut and bolt through the steering knuckle in the tower base wraps it up. By the way, make sure that the nut is on the inside side of the tower. If you ever have to do this again, your bolts will come out to the outside of the car ... not possible if you get them reversed. Don't find out the hard way!
The rear shocks are very conventional little units.
SHIFT LINKAGE
While the Isetta's shift linkage seems simple enough in terms of number of parts, there are several adjustments that you may need to make if you're doing a frame-off job or just tweaking your car after having put some miles on it. The setup consists of a main shift tube that runs front-to-back from the driver's side wheel well, through a hole in the firewall and extends into the engine compartment about a foot. There is a sliding steel rod inside the front of the tube that allows the tube to move and pivot as you go through the gear pattern. The shift lever drops through a hole in the top of the tube and is secured by a round, threaded collar.
In the rear of the car, the main tube is shaped somewhat like a hockey stick. There is an arm welded onto the end of it that hangs down at an angle and faces the engine/transmission. There is a rubber bushing that fits into the end of the angled arm. Securing the tube just behind the firewall is an L-bracket that attaches to the firewall. This holds an L-shaped arm that pivots as the shift tube is moved while going through the gears. One end of the L-shaped arm is attached to the main shift tube with a pin that fits through a threaded clevis. The other end is where the front shift rod connects.
That front shift rod, shorter than its counterpart in the rear, runs from the L-bracket to the top, lateral shift arm on your transmission. That rear rod attaches to the end of the main shift tube "hockey st