Quote:
Originally Posted by TassieBMW
Coming back to this after a while as I'm keen to get this sorted. I replaced the centre bearing and the guibo, it fixed the cowbell noise but there is still a thud during load reversals, where something at the rear end has play in it. Diff bushings seem like the obvious culprit, the only other things I can think of would be driveshaft CV joint or subframe bushings, although I highly doubt the latter. I guess a worn diff with play in the gears is also a possibility but surely not.
|
You're on the right track. Considering all you have replaced the next most likely culprit is the ring and pinion Diff gear backlash. If your Diff whines at 2500RPM when in top gear, then the Diff has some backlash gear tooth wear, The Difff bushings are a known failure point item, they're cheap and easy to replace. However, the OEM Diff LSD is made by ViscoLok and the viscous fluid and discs can cause clunks as well as poor performance at corner exit. The Diff carrier also has a nose bearing but it makes an awful whine when it goes rather than a clunk:
Recommendations:
1) Replace all Diff bushings
2) Check for worn universal joints on the Diff end of the driveshaft
3) Get under the car and try to rotate the driveshaft when in neutral by hand to locate the clunk and determine if the ring and pinion backlash is excessive i.e. the clunk culprit
4) Consider replacing the LSD and getting the ring and pinion backlash adjusted when you're in there.
PS: I very much doubt it's the CV axles because they don't move when your foot is on the brake and that's when the clunk happens i.e. before the car moves.