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E12 M535i Front Airdam installation FAQ

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Courtesy of Adam Wilson

INTRO

Many firstfives members pose the question "What airdam/front spoilers are available for my car?". While this writeup is not an exhaustive E12 front airdam FAQ, there seem to be four main types available with differing levels of availability, installation ease, and look. The first and most widely known is the M535i front airdam which was available on the factory Motorsport E12, the M535i, and as an official BMW Motorsport accessory option through their catalog. The others are made by BBS, Alpina, and Zender. There are a few others out there, but this FAQ will deal with the E12 M535i front spoiler and the associated hardware to install one. Once installed, the front spoiler is also your new front bumper. Since it's made of plastic for the most part, it really doesn't offer any protection but it sure looks good! So be aware of this. The other front spoilers mentioned incorporate either the euro front bumper or US bumper still so in my opinion, they are heavier than the M535i airdam (I sold the original euro front bumper from my M535i after fitting the airdam and it was a heavy sucker. I would guess substitution of the E12 M535i airdam probably eliminates 20 pounds hanging off the front of an E12).

One of the first questions centers around cost and parts availability. Expect to pay about $600-$700 for all necessary parts including the airdam itself and another $150-250 for paint. I was able to get a good deal through the local BMW dealer's body shop from a paint guy working there who did work on the side. He sprayed my M535i front airdam for $150 with Alpine White paint. It looks good but it isn't perfect and about what you would expect for $150. The back side is not painted but that is not really necessary. For parts availability, I went through Maximillion. However the airdam and hardware are really available through any BMW dealership, the trouble can be finding one that is willing to deal with the hassle and help you out. I'm fortunate that there is a local dealer whose parts guys are BMW enthusiasts and after a while they got to know me well from my engine rebuild saga. (Patrick BMW in Schaumburg, IL (Chicago area), your parts guys rule, thanks Curt, Craig, and Dave!). A good parts guy will know their way through the parts CD with ease and they usually get a kick out of looking through the older stuff (like an E12).

An exhaustive parts list is provided below, but when ordering everything, for reference you can tell a BMW parts person to pull it up on the parts CD through the vehicle trim, bumper section, and then scroll to the bottom and select "BMW E12 535i Front Spoiler Motorsport". It will help if you key in a real E12 M535i's vin # by the last seven digits to pull it up. 4145001 will work fine (that would be the first E12 M535i produced, kind of cool if that car still exists somewhere, sorry, got off track). The exploded parts diagram and parts list is shown below.

The goal of this FAQ is to go from this:

to this:

Obviously this FAQ might be a bit off if you have a US bumper E12. I can't guarantee that there are not going to be some minor hiccups and issues to overcome with this. Unfortunately, the E12 M535i front airdam is almost never a simple bolt-on. This project will almost definitely involve some drilling and possibly some very minor paint touch-up and rust prevention with POR-15. POR-15 can be brushed on and is available from their website, POR-15.com.

The first thing to do after you have assembled all of the parts listed above and have your new airdam painted is to assemble the trim on it. Start with the rubber impact molding strips, #3 in the exploded diagram (BMW part #51112210298). Part #4 (51121819910) is designed to slide into the slot on the back of the rubber moldings. You will need one for every hole along the molding area on the front of the airdam, and the moldings will already have bolts molded into their ends that go into the airdam. Part #4 and the molded bolts are secured to the airdam from the back of the airdam by part #5 (51451868108). It is best to work from one end securing the molding bolt by bolt. The point of sliding part #4 in the back of the molding is to ensure a tight, flush fit against the airdam because it can be adjusted in the slot depending on where it needs to go to pull the molding tight. Also do not overtighten #5 because it will cause the rubber molding to look uneven as it is "sucked" against the airdam from the squeeze pressure of #5.

Next, assemble the turn signal pods and attach them to the airdam. This is really self-explanatory so I won't go through it, but the outer lenses do go on last because they sandwich the airdam cutout edge against the turn signal pod. The airdam has molded holes for the little nuts that hold the turn signal pod in there already so it's an easy process. It isn't easy if you try to do it while the airdam is mounted! Refer to the exploded diagram above for an idea of how it fits together. If you really want to challenge yourself, you can look for the clear turn signal lenses that are pictured in my photos. From what I understand, they were only available on E12's sold new in Italy from 1972 through 1974. The realoem.com parts CD lists them for the following E12 models

E12 518 SEDAN, Euro
E12 520 SEDAN, Euro
E12 520i SEDAN, Euro
E12 525 SEDAN, Euro

So anyway, if you are bored enough, good luck because it took me two years to find mine. They're no longer available new from BMW and last I checked, Walloth and Nesch in Germany had only one side (can't remember if it was right or left) and they wanted over $100 for it.

O.K., now the airdam is nearly ready to mount, so it's time to prep the car. The front bumper removal should be straight-forward. On my euro bumper, there were two brackets that went to the frame rails of the car that supported the center of the bumper. The outer edges were attached below the fenders with two screws on each side. Then the whole mess lifted out and was set aside leaving the lower valance still attached. My valence was particularly rusty and cruddy, and it had the addition of some ugly underbody coating rubber junk sprayed on it. It was attached below the radiator/front grille support with body nuts that looked like these:

After removal of the bumper and lower valence you should be left with a frankenstein monster looking something like this:
  

At this point you will want to mount the tow hook assembly to the passenger side frame rail so that it pokes through the front of the airdam. I had to drill new holes in the frame rail to mount mine which was a bit nerve wracking, but it had to be done. Watch for rust forming here from your holes. Some POR-15 would probably help prevent any corrosion from starting if you put a light coat around the exposed metal holes you drill. There is no exact science to the mounting, you just want the tow hook to stick out a bit from behind the airdam. As you can see, I got mine off a bit so it is angled up slightly bumping the airdam. Oh well. I would keep the tow hook out of the mount until the project is finished because it can get in the way when hanging the airdam (or be used as a way of hanging the airdam, depending on how much you care about the new paint you just spent money on).

Now it's time to get ready for the airdam mounting. If you have yet to build your airdam support brackets then now is the time to study the photo of mine and take measurements both on the airdam top edge and under the radiator/grille support. The fit and finish of these airdams isn't perfect like normal BMW components should be so make sure that the holes on the top of the airdam line up with the holes under the radiator/grille support. The body nuts #7 in the diagram (BMW part # 07129901649) are used here and will replace the old, rusty ones that are probably over the holes in your radiator/grille support. Put those new #7 nuts in there and then take your #8 (BMW part # 07119916949) screws and test fit everything (without the airdam). Make sure the holes in your brackets line up under the radiator grille surrounds and loosely attach the brackets with the #7 body nuts and #8 screws. Now remove the brackets and repeat this process only on the airdam to make sure the holes line up there. Trust me, you want to make sure this all works because you need about four hands to get the airdam and brackets hung not to mention having any lineup issues with the holes.

A moment to discuss the point of these brackets. Why not simply forget about them since they are no longer available and you could just mount the airdam right to the underside of the radiator/ grille support? Well, the airdam is flimsy plastic and has a tendency to sag if not properly mounted. The brackets go inside the airdam under the top of it to give it a nice, flat shape like having a metal insert in the plastic. The screws and body nuts clamp this assembly together so that the brackets spread the weight of the airdam across the whole area instead of just where the screw holes are. With this discussion in mind, loosely mount the airdam and make sure that the assembly fits well. Some kind of support for the airdam (that won't scratch the paint) will help and you'll want the front end of the car in the air for easy access. The airdam hangs down low. When you have it mounted, the brackets from underneath should look like this:

The airdam when tightened should fit nice and flush against the underside of the radiator/grille support. The amount of airdam that sticks out should be approximately what is shown below:

But before tightening it, take a moment to connect the turn signal pod wiring because when the airdam is nice and tightly mounted, there isn't enough room to get the connectors to the back of the pods due to the fender liner/brake duct area. Ask me how I know! And make sure the turn signals work as well in case there is any troubleshooting to do now.

Now it is time to mount the airdam to the bottom edges of the fenders. The holes from your euro/US bumper may or may not line up with the holes in the airdam. Mine sort of did and didn't. It was a pain and this is where drilling and bodywork comes into play. Depending on your scenario you may have to drill new holes in the bottom edges of the fenders. The goal is to have the top edge of the airdam provide a nice, smooth seam with the bottom edge of the fender. Mine was not so good partly because of the fit and finish on the airdam in my opinion, partly because of my car having accident damage on the passenger front side. These aren't required by any means, but for $20 from Harbor Freight, a set of body repair hammers have come in very handy at times.

On my M535i, the hole closest to the headlights created a problem due to a tab for holding something, the old bumper I think so getting the nut and bolt through there was difficult.

If you get impatient like I did and use non-BMW hardware to attach this, there can be issues. That's the good thing about using the original BMW hardware on this is that they fit better and are obviously of higher quality. These stainless steel bolts and nuts I bought (*cough* ..umm ... from Ace Hardware, I'm so ashamed, but for a while the BMW parts guys were unable to locate these bolts and nuts) were too soft and bent under the torque to get the airdam on there tight. The good BMW hardware is shown on the left in gold. These were a bit difficult to find so I ordered extra and I'm hoarding it for now. That's one of the reasons why I suggest ordering in greater quantity in the parts list above so that if you lose or damage one of these, you have a few extras to finish the install. Instead of waiting three weeks for an extra bolt to arrive from Germany you'll have an extra to fall back on. The bolt holding the airdam to the fender in the picture below is the correct, BMW parts #9,#10,and #11 from the parts diagram. Once this hardware is secured, put the four caps, part #12 (BMW part #62111243251) over the four part #11 heads to make it look correct and sort of stealthy (in a 1980 kind of way).

Finally, it is time to mount the center brace which is super-easy and completes the look. Failure to mount this will result in the airdam getting pushed back from the force of air over time. This brace keeps it from deforming and pushes it out slightly like a cow-catcher on an old locomotive. The parts listed in the diagram above, #8, #15-19, are used now. Put the body nut, #19, over the hole in the bottom center of the main radiator support. Then attach the rod to the airdam hole slot in the bottom with the intended hardware. Finally attach the other end to the body nut #19 with a #8 screw. The airdam should be pushed out slightly and fairly taut and solid.

Congratulations, the results speak for themselves. You have mounted a great-looking BMW Motorsport accessory to your E12 and hopefully the car has also lost weight due to the absence of a front bumper.

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