BMW E34 driveshaft center bearing and flex disc
How can you tell that the E34 driveshaft center bearing or flex disc is worn?
There is vibration and a thumping noise under acceleration that grows with torque. A rattle is heard when pulling away. The driveshaft is rocked in front of the rear end: too much play means the bearing needs replacing. Replace the bearing and flex disc together, because a worn joint ruins the new bearing.
How is the E34 driveshaft center bearing installed correctly?
The bearing is installed 4-6 mm forward of center and the bolts are tightened to 21 Nm. The bearing is pressed on by the inner race, not the outer race. The driveshaft halves are marked before removal, because the E34 has no factory marks, and the marks are aligned on installation.
What are the most common mistakes when replacing a flex disc?
The driveshaft parts are assembled in the wrong position, the center bearing is not preloaded properly, or the bolts are not tightened to the correct torque. According to the repair manual the torques are M10 (8.8) 46 Nm, M10 (10.9) 72 Nm and M12 123 Nm. Check the gearbox and engine mounts at the same time.