Determining CSB or Differential Noise?

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Mike MPD
Posts: 38
Joined: Dec 11, 2018 6:11 PM
Location: Baltimore

Determining CSB or Differential Noise?

Post by Mike MPD »

The E28 I just purchased has some drivetrain noise. Pretty sure its the csb or the lsd. Any tips on troubleshooting which it might be before I start replacing stuff? I have another project/parts car I am trying to part ways with soon, that I could rob the diff from. But I don't want to go through the effort of swapping just to find out it wasn't the diff at all!

I know I could go ahead and replace the CSB first to see what happens, just trying to make sure Im working smarter not harder

Not sure if video is helpful at all but I do have a quick one from the test drive before I purchased the car.

Thanks!

https://drive.google.com/file/d/1JB7GLu ... sp=sharing
Electricjd
Posts: 27
Joined: May 12, 2021 1:02 PM
Location: Northern California

Re: Determining CSB or Differential Noise?

Post by Electricjd »

Also very interested to hear thoughts on what could be creating this type of noise. Assuming by your video it is also a "constant on" noise and grows louder with speed and does not abate in neutral (I have no vibration - just noise). I was considering wheel bearing (rear - where noise is coming from) or cv/diff as well? We just replaced the diff (to LSD)/cv axles (home rebuild boots) - and likely I've messed something up . . .

Had not considered center support bearing the video in this thread has a different type of noise and the estimate seemed to be CSB. https://www.mye28.com/viewtopic.php?f=3 ... e#p1452632
Mike MPD
Posts: 38
Joined: Dec 11, 2018 6:11 PM
Location: Baltimore

Re: Determining CSB or Differential Noise?

Post by Mike MPD »

Wanted to follow up here, I don't like leaving my topics open ended in case someone else comes across them in the future looking for their own answers.

I replaced guibo and csb and noise it not solved yet. I had someone sit in the back seat and we determined it sounds like the noise is more outboard towards the wheel which makes me think wheel bearing. However, there is no noticeable play in that wheel and the noise does not change when loading or unloading that side of the car through turns which makes me think it still might be the diff?

The only other theory I have is ebrake stuff. The shoes and spring clips things and such are completely wasted, slightly more so on the noisy side. Im wondering if the noise could be metal on metal contact inside the rotor. Pulling on ebrake while driving doesn't change noise at all though so Im not confident. Need to replace that stuff anyway though so I'll probably do that before anything more involved.

Should probably change diff fluid too. PO told me he had already done that in an attempt to address the noise, but he also told me he replaced the ebrake stuff which looks like it could be original to this 300k car.

Electricjd wrote: Aug 25, 2021 2:41 PM Also very interested to hear thoughts on what could be creating this type of noise. Assuming by your video it is also a "constant on" noise and grows louder with speed and does not abate in neutral (I have no vibration - just noise). I was considering wheel bearing (rear - where noise is coming from) or cv/diff as well? We just replaced the diff (to LSD)/cv axles (home rebuild boots) - and likely I've messed something up . . .

Had not considered center support bearing the video in this thread has a different type of noise and the estimate seemed to be CSB. https://www.mye28.com/viewtopic.php?f=3 ... e#p1452632
Sorry I had missed this reply. You are correct that it is "always on" and audible at anything above parking lot speeds pretty much. Noise is related to wheel speed not engine speed and clutch in or neutral doesn't change anything. It changes slightly and briefly if I blip the throttle or when letting off to coast, you can hear what I mean in the video.
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