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Saturday, December 20, 2014

Doug's Domain

Doug Vetter, ATP/CFI

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BMW E36
3 Spoke Steering Wheel Conversion DIY

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Installing a three-spoke steering wheel on a late model E36 is an easy way
to improve the look and feel of the vehicle.

Introduction

About two months prior to completing this procedure my steering wheel started to make a really noticeable and annoying scraping noise that sounded like a plastic rubbing against either plastic or metal. It was hard to tell exactly what was causing it but it appeared to originate from directly under the wheel or perhaps off to the left side a bit. Several online forums suggested everything from the slip ring, to one or more bearings in the steering column.

My 1998 E36 was built in January of 1998. Research in preparation for this fix revealed that in March of that year and until the end of production of the E36 coupe in 1999, BMW equipped the car with various M-Technic parts including the very same 3 spoke M-branded steering wheel that had been delivered on the M3 since 1996. So, in other words, had my car been built two months later it would have come with the three spoke wheel. This made the prospect of a conversion to the three spoke wheel not only technically possible but also historically accurate.

This article may be used as a reference to replace any wheel on any model year E36, but be advised that the airbags and slip rings for the early years (92-95) are not plug-n-play compatible with those of the later years (96-99). It's not to say that you can't get them to work if you are ready to replace a few extra parts and do some splicing, but you will need more information available from various online forums to make that work.

I should also point out that the same three spoke wheel was used on cars later than 1999, but airbags from those cars are of the dual-stage (so-called "depowered") type and the E36 supports only single-stage airbags. Thus, later airbags (particularly those from the Z3 or E46 328/330 are NOT compatible with the E36 in any way -- even if you try to splice it in. Since a non-functional airbag is about as useful as the proverbial tank with a kickstand or sub with a screen door (thanks very much -- I'll be here all week), just don't go there and you'll be a lot happier with the end result.

Prerequisites

Replacement of four spoke non-M wheel with the three spoke M wheel requires the following

Note that you must buy the airbag at a local BMW dealer, as dealers won't ship airbags to end customers. As FedEx and UPS will gladly accept airbags as "dangerous goods" and charge an extra $35 or so to cover special handling, my guess is it's a BMW policy. That theory is backed up by a large sticker on the exterior of the package that clearly states the airbag is to be sold only to "qualified dealers and technicians".

Replacement of the upper steering shaft support bearing requires the following:

Procedure

Removing the old wheel

  1. Ready the vehicle for the work. When parking the car in preparation for this work, make sure that the wheels are straight ahead and that the steering wheel is perfectly "level" or straight. Coupe owners should additionally crack the window about 1/2" before disconnecting the battery since the "blip" feature of the windows obviously won't work without power to the window motors. You should also have the radio security code handy.
  2. Disconnect the ground wire from the battery (the black one closest to the rear of the car). I used a 13mm socket and a stubby extension to help clear the throw of the ratchet from the side of the battery, but you should be able to get away without the extension in a pinch.
  3. Walk away for five minutes to let the car's system discharge. Go ahead. I'll wait.
  4. Remove the two airbag retaining screws accessible from the back of the wheel using a T30 torx. These screws are a little difficult to get to because the turn signal and other stalks get in the way. In fact, I couldn't get the perfect angle for the first few turns of the screw so it wouldn't "grab" with a T30. I had to use the T27 because it allowed a bit of "give" in the angle I approached the fastener. I wouldn't use the T27 any more than necessary, however, as the fit is quite loose and that may strip the fastener. You may also notice that the shank of a typical T30 socket may not fit very nicely in the recess in the wheel. I hate to say this, but just force it. You won't do any real damage to the wheel, and even if you do, you won't see it. As the second screw is loosened hold the front of the airbag to ensure it won't fall out of the wheel. It's unlikely that will happen, but you don't want to stress the wiring if it does.
  5. Lift the airbag out of the wheel and carefully disconnect the horn and airbag wiring. Set the airbag aside, roundel face up, somewhere out of the way.
  6. Remove the center shaft retaining bolt with a 16mm socket. A 5/8" socket also fit nicely and can be used if your toolset exhibits an anti-metric bias. If this bolt has never been removed (unlikely for all E36's at this point), you may find it necessary to apply considerable torque to remove it. Mine came off easily because the wheel has been off at least twice.
  7. Look closely at the metal center splined collar of the wheel that fits over the splined steering shaft. You should see a dot center-punched at the bottom of the wheel and a straight mark embedded in the steering shaft. The dot may be slightly to the right or left of the mark. Make a note of that. Just in case you have to put the old wheel back on, I also recommend you use a fine tipped marker and make three alignment marks at the 9:00, 12:00, and 3:00 positions on the wheel collar and steering shaft.
  8. Slowly pull the wheel off. Be careful that you don't pull too aggressively as that might stretch or break the wires that connect between the rear of the slip ring and the wiring under the steering column. It is possible to tug the connector out of the slip ring and pull some of the ribbon cable out of the slip ring to provide additional clearance between the wheel and the column. Carefully reach into the area beneath the column and pull the horn and airbag connectors out of the receptacles. A small screwdriver may be needed to help free the release of the connectors, but a carefully placed finger did the job for me. When the wiring is free, set the wheel aside somewhere safe.

Replace the upper bearing [ Optional ]

Look closely at the black plastic bearing that supports the upper portion of the steering shaft. You'll want to replace this bearing while you have the wheel off if:

To remove the bearing:
  1. Remove the "outer" steel collar that is loose on the steering shaft. As you remove it, take note of the recess or groove built into it. That serves to differentiate the "outer" collar from the "inner" collar we'll remove in a couple steps.
  2. Remove the snap ring. I won't beat around the bush here -- this is a pain, but it's a doable if you're persistent. First of all, it's best if the gap in the snap ring is facing downward (the 6:00 position) to start. To remove the snap ring, use your knee to stabilize the handles of the long nose pliers. Use one hand to spread the handles and the other hand to put a pick in between the steering shaft and the gap that opens up in the snap ring. I had to work at this 8-10 times to get a hang of it, but I eventually removed the ring. The technique can be a bit crude at times, but do what you must to remove it. Oh, and be careful working with those picks. They can cause real damage to you or the car if you slip.
  3. Remove the "inner" collar that was retained by the snap ring and set it aside.
  4. Pry the bearing out by inserting a flat blade screwdriver in the recesses provided at the 12:00 and 6:00 positions.
To install the new bearing:
  1. Simply press in the new bearing. It fits mostly with hand pressure, but I tapped it in with screwdriver and hammer applied to the outer flange to fully seat it. If it isn't fully seated, it will inhibit reinstallation of the snap ring.
  2. Reinstall the inner collar.
  3. Reinstall the snap ring. While it's possible to do this with hand tools, the easiest (and highly recommended) way to do this is use a small piece of PVC to press the snap ring back into place. Obtain a 1.5" long piece of Schedule 20 PVC (thin wall plastic conduit) or use a sanding drum in a Dremel to sand away enough of the inner surface of Schedule 40 PVC so it fits over the splined shaft. Place the drift over the shaft and tighten the retaining bolt as required to press the snap ring into place. See my front end overhaul blog entry for more information. This technique easily overcomes the considerable steering shaft spring preload and avoids damage to the snap ring that can occur if you simply try to expand it enough to fit over the shaft comfortably.
  4. With the snap ring fully seated, reinstall the outer collar. If the snap ring looks like it doesn't have the clearance required to bed itself into the groove in the steering shaft, thread the steering shaft retaining bolt into the shaft a 1/4" or so and use it as a handle to pull outward on the steering shaft.

Installing the new wheel

This process is essentially the reverse of removal of the old wheel. The only trick regarding the installation of the new wheel is to make sure the wheel is aligned properly. The new wheel came with a center-punched mark on the splined collar in the same position as the old wheel so I used the notes and pictures I took of the old wheel to confirm the correct alignment of the new wheel.

When it comes time to tighten the wheel retaining bolt, BMW recommends 63 Nm or 46 ft*lbs. That is a ridiculous amount of torque for what they're trying to accomplish, in my opinion, and certainly more than can be safely applied to the steering wheel lock. That means you'll need to hold the wheel off the lock and carefully use the torque wrench to apply as much torque as you can below that number. I think I made it to 35 ft*lbs when I said "f-this...I'm going to break something if I keep pushing it). If it's worth anything, removal of the bolt (which had been removed a few times since it was installed in manufacturing), required less than 10 ft*lbs and that didn't come loose. Even 30 ft*lbs would be overkill in my opinion.

You will note in the pictures of the rear of the new airbag that the airbag wiring connector (yellow) is not keyed. However, the metal restrictor arm on the back of the airbag in combination with the angled shank of the connector allows installation of the connector in one direction only. It's a strange way to enforce keying, but I'm sure BMW had a reason for doing it that way. For the record, the long end of the connector body faces downward when installed properly.

Highlights

Conclusion

The three spoke wheel completely changes the way the car feels. The nine and three positions are a bit lower than those of the four spoke wheel, so it's more comfortable to keep one's hands where they should be. The smaller overall diameter of the wheel lends a sporty feel and a more "tucked in" look to the gauge cluster. That's the good news.

The bad news is that it's a very expensive upgrade for such an old car, but I justified it in two ways:

  1. I have plans to keep this car for at least the next 4 years or 100K miles, so that adds only $250 per year to my operating costs: a pittance in the grand scheme of things.
  2. Safety. I was concerned about the ability of a 10 year old airbag to function when I needed it most. There are reasons, after all, why the ballistic parachute systems on aircraft must be repacked every 10 years.

The upper bearing replacement was very simple, aside from dealing with the snap ring. My technician told me everybody has "fun" with the snap rings. He also noted that at one point BMW had a special tool to remove the snap ring but it didn't work. Technicians invariably reverted to the screwdriver and pick approach. The BMW technical manuals now reflect this, as pictures of that special tool have a big "X" on them. Sounds like BMW pulled a "Rosanne Rosannadanna" (Never mind!). So, if you're looking for a better solution to R&R the snap ring, don't bother.