CSB pre-load

[ben4bama]

Preface: my original post (which I've since modified here) was written from the perspective as I understood the Bentley to preload toward the rear given the direction of the arrow in their pic and that the consensus of moving the assembly in forward direction was wrong. I've since been enlightened that I was mislead by those instructions and below is my assessment. Please be aware all the responses below are to my ORIGINAL post of my argument of pushing assembly bracket rearward instead of forward so these responses of pushing the assembly forward are CORRECT:

i'd like to examine what i believe is a confusing topic for CSB pre-loading. The Bentley states to move the bearing forward 4-6mm, It doesn't say move the assembly forward like it should. The picture shows an arrow pointing to the rear of the car next to a picture of the bearing assembly mounts, which if moved rearward puts the bearing forward of the assembly and preloads rearward. Also, note the slots and gap toward the rear of car which indicates you've slid assembly rearward. You can't move the bearing forward on its own, you move the assembly forward which preloads the bearing forward. I believe it was poorly stated in the Bentley and very confusing. it should have stated to move the assembly forward, not the bearing forward since that's what you're really doing and the arrow should have been pointing to the front of the car not the rear. I hope this helps clear up the confusion. The reason to pre-load is to place a little tension on the bearing and rubber to keep the shaft from moving around as much during take off.

[dworthy]

This is not the first time that Bentley has incorrect info, it happens, but you will see a couple of errors inside the pages.

+1 on driveshaft replacement. If you replace both the CSB and guibo at say 100k then it could make the driveshaft last longer, but that would be just speculation on my part. On my old 535i, I did the CSB and guibo, and about 3 months later, needed a new driveshaft as it wore out the CSB again.

[shogun]

Forward = towards the engine is correct http://www.bimmerforums.com/forum/sh...earing-preload
http://www.pelicanparts.com/BMW/tech...ft_Bearing.htm
The workshop manual of the E32 shows it too, and I always make it like that

[bmwdirtracer]

The one I'd posted earlier seems to have been for one with a CV joint; this one has matching measurements to the factory:

FROM ALLDATA, a professional website used by pretty much all independent shops in the country:



Unscrew centre mount.

Installation note:
Preload centre mount in forwards direction by distance A = 4 - 6 mm.
For tightening torque, refer to Drive Propeller Shaft, Specifications.

[shogun]

Preload centre mount in forwards direction by distance A = 4 - 6 mm. The dotted line only giving an idea of 4-6mm and not showing the direction to move from or to. The slots indicate the bracket was moved forward.
Just for your confirmation in addition, here it is mentioned also, pre-load forward to the engine!
http://www.bimmerforums.com/forum/sh...ht=preload+csb
http://www.bimmerforums.com/forum/sh...light=pre-load
http://www.pelicanparts.com/BMW/tech...ft_Bearing.htm

And the Bentley Repair manual is correct for the E36 series, I have the hardcopy at hand here and I retype for you from page 260-4. Driveshaft, installing
1. Align driveshaft matchmarks at final drive and then at the transmission flange. Start attaching nuts. Use new self-locking nuts.
2. Position center support bearing and start attaching nuts. Use self-locking nuts.
3. Tighten flange nuts while preventing bolts from twisting in couping. Tighten final drive flange first, then tighten coupling at transmission.
4. Preload center support bearing by pushing bearing forward 4-6mm (0.16-0.24 in.) from center. See fig. ...
Maybe you misunderstood the word bearing. The center support bearing consists of an inner bearing, a rubber and a outer bracket http://www.pelicanparts.com/BMW/tech...Guibo/pic9.jpg
Here pics of old, defective center bearings
IMAG0616.jpg
IMAG0617.jpg

What has to be moved is the outer bracket with the slots for the 2 bolts and with this you also pull the rubber forward between the outer bracket and the inner bearing, of course the bearing on the shaft is not moved.

Forward on a car is always the direction towards the front. Most good shops even mention this when you order spare parts. How do drivers determine which side of the vehicle is which? It’s as easy as sitting inside the vehicle. While sitting in the driver’s seat, the right side of the vehicle is to the driver’s right, effectively the passenger’s side on LHD, but also on RHD right is right and left is left from the position as sitting inside the car and looking forward. Simple and easy. Always from sitting behind the wheel and looking forward. Same applies for front and rear.

[bmwdirtracer]

Thank you, my wonderful friend, and very great BMW scholar, Shogun. My last post went away somewhere; it was much less complete than yours.

That said, ben4bama is a very knowledgeable guy, and I very much appreciate his very many contributions to this forum. He's being very particular about this, because it has given him issue.....and I appreciate that, because I have fought my way through similar issues that didn't seem to make sense to me.

We've all seen highly conflicting information in the past, and we all strive to find the correct answer. I give praise to all those who have stuck by their answers, and then had the balls to recognize an error. (I've made more mistakes than both of you put together....does that mean I have big balls, no brains?)

Thank you, Ben, for being perfectly pedantic. I strive for that, myself.

Thank you, my magnificent friend Shogun, for being so absolutely correct, exceptionally thorough, and loyal to the correct way, and those who support it.

Ben, per internationally accepted standards, I bow my head, very respectfully. (Yeah, I know that sh*t don't fly in 'bama)
Shogun; I bow deeply, from the waist.

I hope we're all cool with that? Love you both, guys.

[ben4bama]

Thank you, my wonderful friend, and very great BMW scholar, Shogun. My last post went away somewhere; it was much less complete than yours. That said, ben4bama is a very knowledgeable guy, and I very much appreciate his very many contributions to this forum. He's being very particular about this, because it has given him issue.....and I appreciate that, because I have fought my way through similar issues that didn't seem to make sense to me. We've all seen highly conflicting information in the past, and we all strive to find the correct answer. I give praise to all those who have stuck by their answers, and then had the balls to recognize an error. (I've made more mistakes than both of you put together....does that mean I have big balls, no brains?) Thank you, Ben, for being perfectly pedantic. I strive for that, myself. Thank you, my magnificent friend Shogun, for being so absolutely correct, exceptionally thorough, and loyal to the correct way, and those who support it. Ben, per internationally accepted standards, I bow my head, very respectfully. (Yeah, I know that sh*t don't fly in 'bama) Shogun; I bow deeply, from the waist. I hope we're all cool with that? Love you both, guys.

Hey, thank you, Chris, not only for setting me straight and providing supporting documentation, but for the kind words and mainly for your professional attitude during this process. This is the way these boards should operate. You could understand that I wasn't just spouting misleading info trying to cause a debate, I truly do want to help and contribute and the topic wasn't as clear cut from what all I'd read. Since I'm "by the book" on everything and because I wanted to believe the book was correct, I simply tried justifying the direction of the arrow in the pic with semantics in the instructions, which was incorrect. BF is fortunate to have a great resource such as yourself!

MauiM3Mania, thank you for your patience as I worked through this!

Ben

[shogun]

Well, this thread clarified the matter in detail and we found a mistake in one of the books and we now have pics, drawings, instructions, all in here. Will for sure help in the future when this question comes up again.
Thanks to all involved for their contributions.

[ben4bama]

Well, this thread clarified the matter in detail and we found a mistake in one of the books and we now have pics, drawings, instructions, all in here. Will for sure help in the future when this question comes up again. Thanks to all involved for their contributions.

Great, thanks, shogun!

[shogun]

Maybe you inform Bentley Publishers, they have an update service online and I always check that for my cars and manuals I have and print them out and add them to the manual, for example
they have revised the M60 CPS measurement to the correct 540 Ohm instead of 1200 or something like that. Download it here to be update
https://wiki.bentleypublishers.com/d...specifications
Next correction is Intake manifold non-return valve, removing and installing (M60 engine) - addition to group 113 (B794)
https://wiki.bentleypublishers.com/d...113+%28B794%29

For E36 I just could find 2 unpdates/corrections, print it out and add to your manual
170 - Radiator and Cooling System , Cooling system, bleeding
Applies to: BMW 3 Series (E36) Service Manual: 1992-1998 - BSIN B398 , VANOS control unit, installing
https://wiki.bentleypublishers.com/p...ageId=12910609

[ben4bama]

Maybe you inform Bentley Publishers, they have an update service online and I always check that for my cars and manuals

Good idea, I'll do that.

[TonyPa]

I slid my "Bracket" forward. But I only went 2mm. I didnt know it was 4-6mm. Maybe I should move mine ar least 2 more mm? I know mm's are not much, but depends on what your doing.

[ben4bama]

I slid my "Bracket" forward. But I only went 2mm. I didnt know it was 4-6mm. Maybe I should move mine ar least 2 more mm? I know mm's are not much, but depends on what your doing.

I wouldn't go through the trouble. 2mm should be fine. Probably 0mm wouldn't Make any difference.

[TonyPa]

Oh okay. Thank you! I put my new driveshaft on, and literally measured 2mm when I moved it forward from its initial resting point. Now I feel stupid. Lol

[ben4bama]

Oh okay. Thank you! I put my new driveshaft on, and literally measured 2mm when I moved it forward from its initial resting point. Now I feel stupid. Lol

Since its the driveshaft wearing out that causes the CSB to fail and you just installed a new driveshaft and did preload the bearing at least some I'd say you're golden.

[bmwdirtracer]

+1, you're fine, Tony. And the only stupid question is the one you didn't ask. We've all made more BMW mistakes than you have. This doesn't even qualify as a mistake, just a reference point for the future. Be happy, you done good. (Grammatical error intentional)

[TonyPa]

Thank you!!! When I bought the car it vibrated at 30 mph and up. The elderly woman I bought it off of never drove the car...especially the last 3 years. Soon as I pulled the driveshaft I could barely move the front U joint. Was frozen soild.

I seen someone tried to change the Center Bearing and new tranny mounts right prior to me buying it. You could tell they were brand new. So I am guessing a local indy tried to repair but wasnt smart enough to realize the front ujoint is supposed to move??? Ugh

It was a relief when I put a new complete set up on and she drove so nice. Then of course I laid under the car like a yo yo measuring for 2mm forever trying to get it spot on...lol

[bmwdirtracer]

I can't tell you how many people spend lots of time and significant money replacing a CSB. I have learned the lesson the hard way, and I will never, ever do this. I always replace the driveshaft, or I'll send the customer away. CSBs do not die on their own, they die in conjunction with at least one of the u-joints.

[TonyPa]

Absolutely I agree 100%. Looks like they were trying to save money.
Or just lacked knowledge. No insult on them. I just wanted to replace the whole thing. It was well worth the money!

[aesthetux]

Hi - What would be the symptoms be if not properly pre-loaded, or not pre-loaded at all?

I had some rumble (eventually a double rumble) under load when accelerating. Thought it was bad guibo, which was perfect, but CSB was shot. Replaced guibo and CSB, aligned front and back shafts properly, but now I get some new sounds, and still have one rumble when first accelerating under load. I posted the full thread here (last comment): https://forum.e46fanatics.com/showth...1032195&page=2, but the relevant issue here is that I get a "buzz" at high speeds when i barely step on accelerator and just before I fully release it. Almost like a bad light switch when between fully being on and off. Though this could be related to improper CSB pre-loading.

Thanks!

[shogun]

Noise when accelerating and decelerating is the standard symptom. I once had a lose center bearing, on the chassis there are 2 bolts which hold the center bearing in slotted holes, that also caused noise, driveshaft even hit the chassis from below.

[shogun]

some good info on this website from drivetrain , Vibrations Problems BMW, Failure symptoms BMW Driveline, BMW Modifications, High Speed Balancing , BMW driveline Parts, Large stock of Dana Spicer and NEAPCO inventory includes:
•Yoke Shafts •Weld Yokes •End Yokes •Stub shaft ends •Slip Yokes •U-joints •Tubing
https://www.drivetrain.com/parts-cat...s-replacements

[shogun]

as the thread started for another BMW model (1998 E36 M3), here the details for the E32 for pre load of center bearing
BMW repair Manual Nr,6: 2~4mm in driving direction
German language Bucheli Verlag BMW E32 Reparatur Anleitung Band 931: 4~6mm in driving direction
Bentley Service Manual: 4~6mm in driving direction

[CamE32]

as the thread started for another BMW model (1998 E36 M3), here the details for the E32 for pre load of center bearing
BMW repair Manual Nr,6: 2~4mm in driving direction
German language Bucheli Verlag BMW E32 Reparatur Anleitung Band 931: 4~6mm in driving direction
Bentley Service Manual: 4~6mm in driving direction

Well crap. What will happen without pre-load?

Wish I found this thread before doing the job a 2nd time on my 88 735i. No doubt it failed so soon originally (in ~30k miles; replaced in 2019 by a shop while I was at college) because they didn't lknow to pre-load.

So now I'm worried the new one I just installed will fail prematurely. Thought I was doing everything right by replacing transmission mounts + engine mounts at the same time. But alas...
I shall wait to hear how screwed I am

[shogun]

Just fix it now, not much work to pre-load