Vibrations at idle and rear end thud

[Sail Boat]

Hi all,

I'm trying to find the source of engine vibration transfer at idle and a thud in the rear end of my car. FWIW, it's a '91 325i with just under 30,000 miles.

Vibrations: At idle, my car shakes a bit, whether in drive or neutral. It's nothing I'm particularly worried about, but its definitely noticeable. Would the primary suspect be the engine mounts?

Rear end thud: On and off throttle, the driveline makes a quick thud/clunk. I thought it was the diff mount bushing, but after installing a rebuilt LSD, powerflex bushing, and new CSB, the thud is still present (guibo looks good). From what I gather, this is likely related to the U joints? If so, would a new driveshaft be the best option?

Thanks in advance!

[crash n' burn]

I have the clunk in the rear end of the car as well but I've chalked it up to badly worn subframe bushings. This is also a problem in S13s and that's always been the root cause.

[TobyB]

:yes. Or trans mounts. And/or you need a tuneup.

:Thud is more likely bushings (diff, subframe) than driveshaft. But you can always
crawl under and check the driveshaft for loosness, or take it off to see if something's binding.

t

[Sail Boat]

:yes. Or trans mounts. And/or you need a tuneup.

:Thud is more likely bushings (diff, subframe) than driveshaft. But you can always
crawl under and check the driveshaft for loosness, or take it off to see if something's binding.

t

Thanks for the feedback, awesome stuff!

The Trans mounts and CSB have been replaced, along with the diff bushing. According to my shop (RRT in VA), the subframe bushings look in great shape.

I just ordered a rebuilt driveshaft with serviceable U Joints, hopefully that solves the problem. If not, then agree - the subframe is coming out.

[TobyB]

Oh- trailing arm bushings can make noise, too...
...but I bet you checked that, too.

t