Mercedes-Benz W126 driveshaft vibration and rumble
What causes W126 driveshaft vibration or rumble?
Common causes are a worn centre bearing (support bearing), a loose centring sleeve, worn universal joints, rubber flex discs and the support rubber. A bearing causes a rustling noise, crumbled rubber a growl. The driveshaft may move a little, but not wobble.
In what order is the driveshaft mounting tightened?
First tighten the ends at the rear axle and the gearbox, then the support bearing while checking the alignment marks, and last the centre nut. The car must be on its wheels while tightening. The alignment marks are only between the halves of the driveshaft. Removed parts must be installed in the same position as before, otherwise imbalance results.
Does the driveshaft need balancing after replacing parts?
If the vibration remains after replacing the centre bearing, universal joint or centring sleeve, balancing and centring the universal joint have helped. First check the tightness of the centre nut. Some consider balancing unnecessary if the marks line up and the joint has been installed correctly.