re: e28 shakes

[Poland1 <polands@xxxxxxxxxxxx>]

Daniel,
e28 shakes can come from many sources, most of which I've experienced. 
If you need new tires anyway I would do that and make sure they are well
balanced almost before looking elsewhere.  The reason I say that is that
my U-joint symptom was not an "all speeds" thing, and it was
concentrated on cold condtions and loaded conditions, worst in the 1st
and 2nd gear range when you are accelerating.  Then it would go away
when everything expanded a bit from heat.  Several others described
early u-joint wear similarly.  

You might also want to check the "Guibo" or rubber flex disc between the
transmission output and driveline.  If the rubber gets cracked or broken
up, it will allow the shaft to flop around considerably, even to the
point of feeling like its hitting the underbody.  This seems more likely
to be the problem given the 3rd gear (higer shaft rpm) symptom. 

If you had said the shake concentrates around 55mph, I'd say it is
probably tire balance or thrown balancing weights.

If you had said the shake is particularly bad on breaking between 65 and
45 mph, I'd say it was tuckered out thrust arm bushings.

If you get throbbing most of the time when breaking I'd suspect warped
rotors.

My mechanic says he's never replaced an e28 axle cv joint.

My bet #1 would be Guibo.
option #2 would be need rebuilt Portland Driveline Service shaft,
complete with new center bearing, and lubable replacable u-joint. (See
Roundel).

Steve Poland
'88 535is
188,000miles
Portland, OR