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Re: Thumping under the seat (archive)
[ Follow Ups ] [ 3-series (E30) Message Board ] [ Msg. Board FAQ ]
Posted by Ken Juul on September 11, 2000 at 13:32:03:

In Reply to: Re: Thumping under the seat posted by RobW on September 10, 2000 at 00:11:34:

my 87 325 was doing the same thing, just accelerating between 18-25mph. Pulled the drive shaft. Flex disk is shot, Trans mounts are soft from leaking trans fluid and the rear u joint is going bad. I suspected the center bearing, but it looks ok. Getting changed anyway, don't want to pull the Drive shaft again to fix it. Not sure what is causing the noise but all these factors probably contributed.

Could be CENTERBEARING, guibo, diff. mount., and/or u-joint. When things get out of alignment, the centerbearing can give you a "drumroll" like pounding. The diff. mount went soft on my car and shifted the propellor shaft alignment just enough that a u-joint grease fitting (rebuilt shaft) hit the heatshield once a revolution... It drove me nuts for 3 days trying to find that little bastard. Chances are it's the centerbearing. Problem is, the other components are usually not far behind...

RobW
'81 320i (ex)
'85 535i (ex)
'91 318is


Got a 88 325i - lately every time I accelerate from a standstill, I get a loud thumping under the front seats. I assume its the tranny or drivetrain. Anyone heard of this. Do I have an easy fix with a new mounting bracket or am I on my way to home mechanics hell.





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