SbolenC36

Hi all

I know there have been many threads regarding rear end noise but after hours of search I can't find anything with my exact symptoms. A few days ago I notices a metallic, quite loud, clunking (more pronounced than a click), coming from the rear end at low speeds and under normal acceleration from stop lights. Key observations:

-Only occurs when gas peddle is pressed and goes away with speed (or I just cant hear it with the wind noise).
-Noise still somewhat inconsistent, last night I drove home and didn't hear anything.
-Seems to be coming from the rear end, possible more toward passenger side.
-Noise is metallic and loud "clunking" not "clicking", but is sometimes (not always) in sync with movement of car at low speeds as if a cv joint issue.
-Noticed oil coagulated on bottom of diff housing.
-CV Joint boots are fine, not torn.
-Flex plates in good condition.
-Shock mounts are fine.
-Lug bolts are factory and I have already ruled out them hitting the parking brake.
-CV JOINT OBSERVATION: So I noticed that when I move the half shaft on the drivers side back and forth (from diff to hub and back again vigorously) there is a few centimeters of play and no noise made, which I assume is normal. When I do the same on the passenger side half shaft, the shaft barely moves and there is a clunk sound that can made by inducing this back and forth movement. Could this mean the cv joints on this side are shot? Would a bad cv make the half shaft have decreased flex back and forth?

My doubts come from my experiences with a bad cv joint on a Porsche I owned several years back. The noise from that cv joint was a consistent "clicking" not "clunking" and was constant regardless of whether the gas was pressed or not.

Any help on this issue would be much appreciated! I can provide more info if needed. Thanks guys

What a way to spend a Sunday..

Car: 1995 C36, 150k miles, 18" mono's

SbolenC36

Also looking for drain and fill plug hex head size for rear diff fluid change

SbolenC36

Update: Just changed the diff fluid and holy s#%! it was dirty! Definitely needed the oil change for sure. Drove the car around a bit and no noise Not sure if it was the actual fix, since I didn't hear the noise last night when I drove home either, but I'll see how the next few days pan out and keep an eye on it. Still thinking the CV joints might need a look at...

*Found the fill and drain plug size on the diff: 14mm hex

Ausmbtech

CV joint problems are very rare on these cars, but they are still possible and sounds quite likely in your case. Wheel bearing, diff bearing and diff gear problems would give a constant and/or easily reproducible noise. Might be worth taking the shaft out and checking on the bench before it gets much worse.

SbolenC36

Thanks for the tip. Good to know CV issues are not common on our cars. That will be my next step, taking the shaft out and giving it a good go through. Good news is the noise has yet to come back, but its still worrying me...