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RE:Thumping noise in drivetrain

Matt

Couple of things that will be the culprit:

1. Centre bearing/centre bearing housing.  This is the bearing that joins 
the front driveshaft to the rear section of the driveshaft.  Its located 
above the exhaust about in the centre of the car.  The rubber surrounding 
the bearing goes south and the bearing floggs around in the housing. 
 Possibly not this because the drive shaft really thumps the driveshaft 
tunnel quite hard when you first take off.

Not a big deal to replace, but make sure the centre bearing has pre-load 
before you tighten the mounting bolts.

2. Universal joints.  This is a killer.  Your problem might be worn 
unijoints at either the diff end or the tranny end OR BOTH :-(

You might like to check the technical FAQs to see what your options are 
here.  The best approach is to replace the complete driveshaft - quite 
expensive even over in the US (almost prohibitive here in OZ).  The other 
alternative is to have the unijoints machined out and some replacements 
pressed in.  You might have some balancing problems - a chap here in OZ had 
lots of drama with balancing replaced unijoints on the existing shaft of his 
E32, but eventually found someone who could do the work.  So, check the FAQs 
or hope that someone else replies over there who has had this problem.  I 
can remember a couple of months ago, a thread on driveshaft replacement on 
an E24 6 series.

3.  Giubo.  I'm not sure if E32s have one of these donuts, but this should 
also be checked if you have one.

Hope this helps

Steve Callaghan
BMW Club Queensland, Australia
E23 7series