Drive shaft answers (archive)

A driveshaft with a bad center support and shaft vibrates on acceleration because the U-joint binds and the shaft then does not spin true, but spins with a bend at the joint. This starts manifesting as a vibration, then goes on to rip the center support rubber out as it gets worse. This allows the shaft to hit the tunnel under hard acceleration. The joint binds because it is old and all of the lube has dried up. The vibration goes away under cruise conditions because there is no longer a momentary torque on the shaft, but smooth power (i.e. no sudden acceleration of the shaft or large speed differential between the front and rear of the shaft.) If you must check after the mechanic:

First, look at rubber guibo for cracking. It will be obvious.
Second, move driveshaft up and down while looking at center bearing. Usually the problem is in the rubber surround, not the bearing itself. Torn rubber is usually a sign of a bad shaft. Replacing only the bearing itself will simply incur the exact same labor times (if not more due to the need to press the bearing off the shaft) as replacing the shaft, except that you have to do it twice because you will then have to go back and replace the driveshaft later.
If neither of these are visibly bad, it is the driveshaft, usually the problem on these cars after many years and miles. This is also the time to replace the guibo. Driveline Specialties from PORTLAND, OR is the only way to go- they have these in stock, and you can get a CCA discount. Total is about $400 with shipping. Comes with replaceable and greaseable U-joints and an installed center support as well as paid return shipping for the core.
Your mechanic is speaking from years of experience with e28s. My family, myself, and my ship have replaced a total of 8 driveshafts, with the DLS units. All are going strong and all cured the vibration problem. I have no affiliation with DLS, but am a happy customer. I am also a mechanic and have one of these on my 88 ///M5 which cured my vibration problem.

Follow Ups:

[ Follow Ups ] [ M5 (E28) Message Board ] [ Msg. Board FAQ ]

Questions, comments, or problems, please visit the Roadfly help desk.