Drive shaft center support bearing orientation?

PixMan · Post by **PixMan** » Oct 23, 2008 7:12 PM

The Bentley's isn't totally clear to me on this, so perhaps someone can tell me:

The bearing assembly has an "open" and a "closed" side. Which end points toward the front of the car, and in which direction is it pushed that 1 to 2 mm for pre-load?

Post by **Brad D.** » Oct 23, 2008 11:25 PM

The open side goes towards the front of the car and you preload it towards the front as well.

Post by **Nebraska_e28** » Oct 24, 2008 10:41 AM

I was in this same boat once & had to look an old DS to figure it out. One other wait is how the CB is offset to one side. You can look at how the DS aligns in the tunnel & pretty much deduce how the CB would go. Or just ask of course.

stevgtguy · Post by **stevgtguy** » Nov 21, 2011 11:45 AM

Brad D. wrote:The open side goes towards the front of the car and you preload it towards the front as well.

Is this definitely correct?

I find pics all over the web of BMW driveshafts with the bearing mounted both ways. I installed one this way and it never got better & then I replaced it and put the new one in with the opening facing rearward and it got better, but still clunks a little.

I have all new mounts everywhere except the diff mount and I'm thinking that is the culprit. Either that or my rear axles are out of balance.

Orientation is the first things I need to know for certain though. Thanks.

alijonny · Post by **alijonny** » Nov 21, 2011 12:08 PM

I wouldn't doubt Brad D.

stevgtguy · Post by **stevgtguy** » Nov 21, 2011 12:40 PM

alijonny wrote:I wouldn't doubt Brad D.

He gonna send his goons after me if I do??

I don't doubt him, I just want to know where the information came from. As I am sure many members can attest to, CSB thumping is annoying as hell and the elimination of it is of my utmost concern. I just want to make sure I am really installing it correctly since I have done it both ways and it really doesn't change much.

However, I noticed that by installing it "backwards" that it is easier to pre-load without over doing it.

LandCruzer94 · Post by **LandCruzer94** » Nov 21, 2011 1:19 PM

Mine is oriented the same way and has been that way for 10+ years...

stevgtguy · Post by **stevgtguy** » Nov 21, 2011 1:35 PM

LandCruzer94 wrote:Mine is oriented the same way and has been that way for 10+ years...

The same way as Brad D or the same way as mine?

Post by **Brad D.** » Nov 21, 2011 3:04 PM

What is the sexual orientation of your CSB?

stevgtguy · Post by **stevgtguy** » Nov 21, 2011 3:40 PM

Brad D. wrote:What is the sexual orientation of your CSB?

Hi, my name is Otto. I enjoy long walks on the beach and I prefer my center support bearing to be backwards.

Post by **Brad D.** » Nov 21, 2011 3:50 PM

stevgtguy wrote:
Brad D. wrote:What is the sexual orientation of your CSB?
Hi, my name is Otto. I enjoy long walks on the beach and I prefer my center support bearing to be backwards.

demetk · Post by **demetk** » Nov 21, 2011 5:15 PM

stevgtguy wrote:
Brad D. wrote:The open side goes towards the front of the car and you preload it towards the front as well.
Is this definitely correct?

stevgtguy · Post by **stevgtguy** » Nov 21, 2011 5:25 PM

What's the source of that image?

Also, other than premature bearing failure, what harm may come from installing it backwards?

demetk · Post by **demetk** » Nov 21, 2011 5:33 PM

stevgtguy wrote:What's the source of that image?

Also, other than premature bearing failure, what harm may come from installing it backwards?

Shop manual. Now I need to get underneath and check mine.

Not sure if it's symmetrical with respect to the mounting holes.

steve 87 535is · Post by **steve 87 535is** » Nov 22, 2011 8:00 AM

I agree with Brad-open and preload to the front. I have two unmolested driveshafts sitting here that have it that way also. I thought it was backwards once but, caught the mistake before I installed the shaft.

shagrath · Post by **shagrath** » Nov 22, 2011 8:32 AM

Brad is correct. Take it from someone who has messed with DS's recently as a few months ago... a few times.

stevgtguy · Post by **stevgtguy** » Nov 22, 2011 10:56 AM

shagrath wrote:Brad is correct. Take it from someone who has messed with DS's recently as a few months ago... a few times.

I'm just in denial because I took off work last Friday and spent most of the day under my car to change the center bearing and now I'm going to have to drop the driveshaft for the third time in a few months. It's easy, but also a PITA.

Mike W. · Post by **Mike W.** » Nov 22, 2011 11:06 AM

demetk wrote:
stevgtguy wrote:
Brad D. wrote:The open side goes towards the front of the car and you preload it towards the front as well.
Is this definitely correct?

Odd. Everyone I've ever had has been like the pic with the closed side pointed forward. Mechanically I don't see any difference on the bearing, preload is preload, possibly different stresses on the rubber membrane, but more danger of dirt and debris contamination if open is forward.

And I've only had 15 or 20 BMWs with center supports like this.

bojangles · Post by **bojangles** » Nov 22, 2011 9:40 PM

RealOEM clearly shows the open side forward.

funny thing about the picture, is that is shows the csb on with the male splines, I think that the e28 driveshaft has the csb on the half with the female splines... the image may not be from an e28

Bimmerguy2002 · Post by **Bimmerguy2002** » Nov 22, 2011 10:09 PM

bojangles wrote:RealOEM clearly shows the open side forward.

funny thing about the picture, is that is shows the csb on with the male splines, I think that the e28 driveshaft has the csb on the half with the female splines... the image may not be from an e28

the rear has the little collar nut, the front side has the csb. Also the bentley shows a pic with it front and another with the open end backwards, which is incorrect.

PINGAS

demetk · Post by **demetk** » Nov 22, 2011 11:27 PM

bojangles wrote:RealOEM clearly shows the open side forward.

funny thing about the picture, is that is shows the csb on with the male splines, I think that the e28 driveshaft has the csb on the half with the female splines... the image may not be from an e28

That's right, the open side is forward. The driveshaft's front section has the u-joint section with the splines. It helps if you view that pic while standing on your head.

Here's the e34 Bentley:

wkohler · Post by **wkohler** » Nov 22, 2011 11:46 PM

Mike W. wrote:
demetk wrote:
stevgtguy wrote:
Brad D. wrote:The open side goes towards the front of the car and you preload it towards the front as well.
Is this definitely correct?

Odd. Everyone I've ever had has been like the pic with the closed side pointed forward.

Mike, the splines are on the rear of the front half, so the photo is still correct with "open side pointed forward."

stevgtguy · Post by **stevgtguy** » Nov 23, 2011 10:17 AM

wkohler wrote:Mike, the splines are on the rear of the front half, so the photo is still correct with "open side pointed forward."

I'm pretty sure that I'm still having a problem because of either a bad diff mount or right rear half axle. This much is for certain though, the vibration got a lot better when I flipped the CSB around "backwards".

So I got to thinking that since the bearing is in the center of the rubber and it installs facing either direction easily, the only real difference is the direction the rubber is facing. Since the Bentley says this is a dust boot for the bearing, I wonder if the preload has anything to do with the bearing design itself or just the fact that it is a bearing on a two-piece driveshaft.

From my experience, the direction does not matter so much as having the circlip installed and a decent preload on the bearing.

Also, has anyone ever thought of filling a CSB with urethane and would that make it better or worse at absorbing vibrations?

Post by **Jeremy** » Nov 23, 2011 10:57 AM

What brand of CSB was it that you installed? The cheaper varieties have gotten considerably worse in terms of quality over the last few years.

Jeremy

stevgtguy · Post by **stevgtguy** » Nov 23, 2011 11:28 AM

Jeremy wrote:What brand of CSB was it that you installed?

The first one was MTC I believe and the one I just put in is a Uro Parts with a yellow inner seal.

I have also used Febi & Hamburg-Technic before.

This is the 5th center bearing on my car in the last 4 years. I probably should have my u-joints looked at and have my driveshaft re-balanced as well as replacing the rear diff mount and probably the half axles as well

Everything from the center bearing forward is new within the last few months (motor mounts, tranny mounts & guibo) I love my e28 but damn what a money pit.....

Post by **Jeremy** » Nov 23, 2011 11:35 AM

The Uro Part pieces are garbage. Have the u-joint checked if you feel something is amiss, but I'm willing to bet it's the CSB itself that's the problem. I had one new out of the box that operated like a nearly completely failed CSB.

Find the best price you can for the OE part (can't recall the manufacturer now) from a dealer. It's the only one I now trust in terms of quality for that part.

Bimmerguy2002 · Post by **Bimmerguy2002** » Nov 23, 2011 11:37 AM

Jeremy wrote:The Uro Part pieces are garbage. Have the u-joint checked if you feel something is amiss, but I'm willing to bet it's the CSB itself that's the problem. I had one new out of the box that operated like a nearly completely failed CSB.

Find the best price you can for the OE part (can't recall the manufacturer now) from a dealer. It's the only one I now trust in terms of quality for that part.

Did you find that they were flimsy as hell? The e34 one is way sturdier, like 2x as thick.

stevgtguy · Post by **stevgtguy** » Nov 23, 2011 11:50 AM

No matter what brand I have purchased, it appears that the rubber on all of them is almost too soft to preload properly.

That said, I should probably investigate the rear end of things before I get robbed at the stealership for another center bearing.

I have owned 3 BMW's over the course of 5 years and have never called or set foot on a BMW dealer lot.

Post by **Jeremy** » Nov 23, 2011 11:53 AM

Bimmerguy2002 wrote:
Jeremy wrote:The Uro Part pieces are garbage. Have the u-joint checked if you feel something is amiss, but I'm willing to bet it's the CSB itself that's the problem. I had one new out of the box that operated like a nearly completely failed CSB.

Find the best price you can for the OE part (can't recall the manufacturer now) from a dealer. It's the only one I now trust in terms of quality for that part.
Did you find that they were flimsy as hell? The e34 one is way sturdier, like 2x as thick.

"Flimsy as hell" is an apt description. Will the e34 CSB fit the e28? If so, that might be the answer to all these CSB problems we've been seeing.

stevgtguy · Post by **stevgtguy** » Nov 23, 2011 12:22 PM

Jeremy wrote:Will the e34 CSB fit the e28? If so, that might be the answer to all these CSB problems we've been seeing.

I could see it fitting or possibly not.

Check this photo of the e34 non-540 center bearing

MyE28.com

MyE28.com

Drive shaft center support bearing orientation?

Drive shaft center support bearing orientation?