While I had the car up on stands today looking for some clunking noise in the rear end (I know I know, just hurry up and get the Bilsteins rebuilt and those new Eibach springs installed ) I noticed that the output flanges on the diff are free to move in and out somewhere between 1/8" and 1/4". Is this normal?

Mike

 

Well, sorta. Mine have been like that for ages. If you notice the clunk when you switch from drive to reverse and perhaps sometimes when changing from acceleration to deceleration, then this looseness in the diff could be involved. If your clunk is at other times, then look elsewhere.

In my case when I opened up the diff, the ring and pinon backlash was fine but the small gears in the center rocked on their shaft, possibly from worn bearing/bushings. You have PSD and can't see the small gears hidden in the center of the limited slip. Anyway, even though I had this play I rarely noticed any clunk or other adverse effect. I drove with it that way for many years and it never got worse.

Mine looks closer to 1/8th inch...


Here's the translation of that looseness into rotational play. In response to this video somebody commented "They all do that." I checked some other 928s and they had less play but still some.

 

Thanks Bill. That looks similar to what I'm seeing. The noise I am looking for is more like suspension rattle from a bad bushing or a busted shock. I only really notice it when going over ripples in pavement. Sometime this winter I am going to get those shocks rebuilt. When I do I will also most likely change the upper link bushings.

Thanks for the vids.

Mike