Rear end clunk-Play in diff?

[Roysneon]

So when I take off hard/drop clutch/shift hard there's a terrible, dull thud from the rear end. It also wheel hops until it stops clunking. I changed the diff bushing thinking it could be that, but it's no better/maybe worse now.

I finally got under the car again today and poked around a bit. I know the rear ta bushings and subframe bushings are dry rotted, but I don't see that causing this noise.

I turned the rear wheel by hand and there was what I would say is play in the diff. There was a lag between the halfshaft turning and the driveshaft turning and a clink when the driveshaft did start to turn. The only thing besides the diff I thought it could be was the CSB but I don't see that causing what I just described. Guibo looks fine.

Car is 1993 M40 5mt touring fwiw.

Should I be looking for a lsd to replace the diff?

[Ceeker]

check your u-joint..

[Roysneon]

Well from what I saw the input from driveshaft to flange on the diff wasn't tight to the rotation of the diff's output shaft, that makes me think there's slop/play inside the diff.

[jlevie]

Wheel hop sounds like bad bushings and/or shocks. The "clunking" under hard acceleration sounds like binding drive shaft u-joints and a failing center support bearing.

[shiboujin]

90% of the time it's a dead U joint or your subframe bushings are dead. I'm betting subframe bushings. esp if the clunk is mainly on one side.

[Roysneon]

Just got under the car again for a better look. Subframe bushes are definitely shot, and when I turn the driveshaft just after the transmission, there is a metalic click/clunk from the CSB area.

I'm going to replace the subframe/Trailing arm bushes when I have the time and space (car is my DD) and look into doing the CSB as well.

[Goya20]

From past experiences sounds like you have yourself a u joint problem.

[Gruelius]

probably sounds like wheelhop but is tailshaft related. been happening to me since i decided to rest my whole rear end on the rear ujoint. trying new guibo+CSB will post results. got new oe sub/trailing bushes and a solid mz3 diff bush. new e36 strut tops too

[HasteTheMoment]

Sounds like same issue I have. From a dead stop ill go from 1st then into 2nd and i get a CLUNK. Same if taking off fast.

[KenC]

Hows your flex disc look? I bet it's gone.

[Roysneon]

Hows your flex disc look? I bet it's gone.

Flex disc? Is that another name for the guibo? If so, it looks fine. I'm getting the car on a lift by this weekend at the latest and having it looked over by my father (mechanic). I now know for sure I'll need subframe bushes and swaybar links as soon as I can, but I don't think this is causing the symptoms that are bothering me right now.

[99em1]

Let's say you're about to take off in 1st... you feel what's almost like a slight delay, then a clunk, then you start accelerating, then thats a bad U-joint?

[jlevie]

It can be.

[99em1]

Interesting. What should I look for in terms of U Joint play the next time I get under the car?

Also, what else could it be except the CSB?

[Roysneon]

90% of the time it's a dead U joint or your subframe bushings are dead. I'm betting subframe bushings. esp if the clunk is mainly on one side.

Winnar. Both subframe bushings were beyond dead; as in almost totally missing. They were likely very dried out/cracked when I bought the car and my hoonery completely did them in. The entire subframe could be moved up/down with a prybar they are so bad.