Driveshaft support bearing dust shield installation

[M6csi]

Well, my driveshaft project has not been completed yet, but slowly but surely. Here are some tips on the how the support bearing and it's 2 dust shields ought to be installed.

The excellent condition used rebuilt driveshaft that I'd bought off ebay was not outfitted with dust shields on the fitted support bearing. Although, I was tempted to leave it as is, but then had a change of mind when faced with a possible premature bearing failure due to to lack of the shields to keep out dust and grime.

On removing the support bearing, it was not that difficult. Since I did not have a gear and bearing puller, I just used a big screwdriver and drove out the bearing with a big dead blow hammer. Have to admit this is not really a good practice as the u-joints may get damaged by the repeated hammer blows. Ordered a couple of sets of the inner and outer dust shields from Bmw (only source?) and proceeded to install a new Febi/Bilstein bearing ($21) with the shields fitted, only to find out I had install the bearing backwards. In the meantime, I had purchased one of those cheap gear/bearing pullers online and it sure made the removal of the support bearing a breeze. Have to say buying the puller is one of the best $37 dollars ever spent. Well, out came the bearing again to correct my mistake, this time with the proper orientation.

One tip on the bigger dust shield installation is to insert it into the DS first prior to the actual fitting of the support bearing. It is made of a real thin stamped sheet metal and amazingly tight fitting and needs to be gently tapped into place, once in place, it cannot be removed without it being deformed. These are only a few dollars a piece so it will be a good idea to order a couple of sets of the inner and outer cover seals just in case mistakes are made.

To drive the bearing home into the driveshaft, I used a short section of my aluminum floor jack handle for a drift tool. It was the correct diameter to accommodate the splined section of the DS, worked out perfectly. An appropriate metal pipe of the right diameter can also be used, do not use a pipe that extends beyond the inner metal bearing surround as this will damage the plastic cover and the internal ball bearings. Put DS in a vise, slip in support bearing evenly and hammer it home. Slip in dust shield and install circlip, just make sure the clip is securely fitted into slot on driveshaft. If the circlip cannot be fitted then the bearing needs to be driven in more to clear the slot.

One other tidbit on the Febi/Bilstien support bearing, to my surprise, the part is made in Germany and not one of those made in Brazil/Mexico/China craps. Just wondering who the oem manufacture was?

Hopefully, I get get the DS project finished by next week.

Here are some pics of the proper dust shield installation.

[86GT635]

how'd ya know it was on backwards? IIRC it is not very clear in the bentley. The way you have it looks to be correct, considering when you pre-load the bushing, it will naturally want to pull reversely than installed, providing the correct absorbtion.
-DJ

[M6csi]

how'd ya know it was on backwards? IIRC it is not very clear in the bentley. The way you have it looks to be correct, considering when you pre-load the bushing, it will naturally want to pull reversely than installed, providing the correct absorbtion.
-DJ

You're right about the installation instruction in the Bentley manual as it is rather vague. If one is not familiar with it's correct orientation, then one can easily make this mistake such as I did.

The proper fitment is to have the circlipped side of the bearing facing out (facing splined shaft).

[mmk19]

Hey M6csi i just changed the center support bearing with my father on my 83 635csi. He did not let me do it myself because he did not trust me probably because im sixteen lol.

Anyways once we replaced it we test drove the car and it had some heavy vibration from the drive shaft only if you drive the car really hard. But the vibration starts when u shift and continue to accelerate then it fades. Do you have any idea why it would give off a vibration like that?

[Bert Poliakoff]

Did you put the two 1/2s back exactly the way they came apart?/ Your father or you may not realize if you didn't, you probably through the ds out of balance

[M6csi]

Hey M6csi i just changed the center support bearing with my father on my 83 635csi. He did not let me do it myself because he did not trust me probably because im sixteen lol.

Anyways once we replaced it we test drove the car and it had some heavy vibration from the drive shaft only if you drive the car really hard. But the vibration starts when u shift and continue to accelerate then it fades. Do you have any idea why it would give off a vibration like that?

Since I'm not an expert mechanic and this is the first time that I've ever tackled a driveshaft project, so it'll be hard for me to pinpoint the exact causes of your car's vibration problems.

Here is my take on your situation, some are fairly obvious, so don't take offense to them:
1) Was the support bearing installed correctly (bearing spins freely with no
binding?
2) Were the dust covers and circlip fitted? If the dust cover that is
locked by the circlip is missing then there maybe some movement by
the bearing due to the approximately 1mm of extra play.
3) Was the bearing support preloaded prior to the final tightening of the
securing bolts?
4) Was the DS aligned properly prior to tightening?
5) Were the mounting bolts for the guibo/transmission and differential
securely tightened and torqued properly?
6) Defective guibo?
7) Finally, what is the condition of the just replaced driveshaft, new, old,
or rebuilt? Even though it maybe a rebuilt shaft, it could be a defective
unit nonetheless.

Hope this helps!

PS: Neglected to mention what Bert P. stated! if the front and rear shafts are not properly oriented, rotate the the front shaft 180 degrees, this should solve the balancing problem, if indeed this is the case.

[DaHose]

Well, I'll chase you around here too, Bert.

I second the out of alignment issue. The driveshaft on an E24 is balanced as a complete unit. If you split it and put it back together in a different alignment, then it will vibrate and needs to be re-balanced.

Also ... ALL S38/M88 OWNERS BE ADVISED!!!!
If you work on the car in a way that could cause the engine to rotate backwards, you can cause the timing chain to skip at the crank and it will ruin your valves. ANY work that could cause your engine to turn backwards should be followed by a mechanical cam timing check BEFORE YOU ATTEMPT TO START THE CAR! I know it shouldn't happen, but I am on the verge of opening up my engine to replace my valves because the above happened to me. I strongly recommend replacing your cam chaing tensioner with an M3 version as well. They have stronger springs and protect your engine better.

Jose

[CW6er]

Some shafts have alignment marks on the two halves, others do not and you have to mark them. If you get them mixed up, the U-joints should be aligned as in the picture, so there are only 2 ways it can go on, 180º form each other.

[M6csi]

Jose,

I've been following your engine problem with interest too. Hope you can rectify the problem soon.

Just curious, how much did the DS rotate backwards anyway? So what is the proper technique to use when removing and installing the mounting bolts for the DS...put the tranny in neutral or put it in gear and lock the parking brakes to prevent the DS from rotating?

[DaHose]

Backward rotation was probably 1/4 to 1/2 turn. Seems like the tension and sudden release (as the bolt gives) works in concert with the weak tensioner to create freaking destruction. I will NEVER put the tranny in gear again when I work on a drivetrain. Hell, I don't even want to push start a damn car right now. What if it bucks and kicks back. BLAH!!!!


You got it, Bert. Proper way is tranny in neutral and e-brake on. Works for both removal and install. I had my control arms off the car, so the only help I could get was engine compression while I put all my effort into the wrench. Otherwise, I would have been using the damned e-brake and everything would have been just fine. If I ever have to do that work again, I will be sure the e-brake is functional or have a second body there to hold the opposing wrench.

Jose

[dm635]

Febi is good stuff. Stay away from any scan-tech crap, unless you want to do the job a second time.

[mmk19]

Did you put the two 1/2s back exactly the way they came apart?/ Your father or you may not realize if you didn't, you probably through the ds out of balance

we did the rotation it stopped a lot of the vibration still have a little bit of it. but the support bearing we got was apparently a cheap one so we picked one up from the dealer and we replaced it and now its perfectly fine

the driveshaft is original along with the tranny and engine this car has been sitting for years and i begged my father to give it to me and so we cleaned it up reupholstered the recaro seats, paint job and basic maintenance to get it running right...i love the car and cant wait to get it next week