Not sure what the problems is so I will try and describe it.
When accelerating in 1st or 2nd gear, I get a jerky rocking motion from the rear of the car. There is also a gentle knocking sound associated with it.
Anyone know whats up with the car?
Wheel bearing or maybe UJ on the propshaft?
JB
Driveshaft centre bearing? Rear subframe bushings?
I had the exact same problem on my 1987 320i. Driveshaft centre bearing eventually packed up and the driveshaft rebuild cost me the equivalent of
450 US$. This included the rubber driveshaft coupling. Unfortunately the ID10T that rebuilt it used spares form I don't know where and the car had a vibration at 120km/h. Sent the car back, but ended up having to live with it. They insited the vibration was caused by my tires being out of round, which I had balanced with no effect.6 Months later I took my car to a clutch/brake and driveshaft specialist who replaced the pirate parts on the driveshaft with genuine BMW parts, and another new rubber coupling. Now the car is running smoothly on the same set of tires.
The jerky rocking when you lifted off the gas, was much better immediately. You may also look into replacing the CV joints on your two sideshafts, as this may also be a cause of some play. I very much doubt that you have any problem with your diff.
MW
It sounds like you need any of several different joints in the drive shaft.
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