Low Speed Rear End Clunk, slightly metallic

[6SPD]

Since I acquired my E30 in January, it has had a clunking in the rear end at low speeds. It seems to occur at parking lot speeds when there is slack in the driveline, i.e. going from throttle to no throttle and vise versus. I know that all drivetrains have some slack to them and I can definitely feel the slack, but there is a clunk that comes along with it. Lately it has started to have a slight metallic sound to it.

The current condition of the rear end has been looked at. I recently dropped the subframe and replaced the rear subframe bushings, trailing arm bushings, diff bushing, brake lines, parking brakes, rotors, and pads. The driveshaft also looks brand spanking new. Last night I grabbed the half shafts and attempted to raise them up and down to now avail, in attempt to check the CV Joints.

I'm at a loss to what the clunking is originating from. I would like to have a very sound and planted rear for my E30.

Thanks for any replies in advance

-D

[pantelones]

I had an identical issue after doing lots of work to my car, and I swore that it was to due with the pre-load on the diff, and the sequence torque on the g260 output flange nut. After re checking both my problem was lessened, but not gone. Honestly the clutch pack type LSD is prone to clunk, and your clutches, dog ears, or bearings may be worn in the diff. Also, if you are unaware, you need to tighten the rear trailing arms while the car is under load. Failing to due so will cause the clunking to be exaggerated. Honestly it's black magic to make it silent. I just learned to change my driving habits, out of sight out of mind. Am I right? ahahah

[mulletman]

I have a similar clunk/looseness in my drivetrain. I just had the whole subframe apart... So my plan of action is checking the tightness of my trailing arms, replacing the guibo, and probably replacing the half-shafts. I am also planning on fabbing up some better rear sway mounts to replace my cobbled-together UUC mounts.

[jlevie]

If the sound can be triggered by changes in throttle when moving at low speed on a level surface, the cause will be wear in the drive train. The could be in the transmission, drive shaft, differential, or half shafts. With the car up on a lift a check for rotational play in the drive shaft and half shafts con be done and by triggering the behavior one tell if it is from the differential or transmission by where the sound comes from.

Having said that, my best guess in this case is a worn differential.

[E30_fiend]

I was going to say the same as Jim.

I had this issue for a while a year or so ago. Changed everything. Bushings, half shafts, driveshaft. Suspension. Everything except the diff. I swapped in a different ratio LSD and what do you know, noise was no longer there. The 4.10 I took out seemed to have been a bit worn so it woulf make noise at low speeds.


Taylor