Clunk in drivetrain when engaging/disengaging the gas...
 

makes highway driving very uncomfortable. Its like a lash.

Only happends when lightly pussing on/letting off the gas at higher speeds.

could it be due to my clutch? installed without adjusting SAC... I just put in RS4 motor mounts. Stock tranny mounts. APR snub.

I checked my rear diff mount...the rubber looks perfect.

Recently my exhaust started banging lightly over big bumps on the highway.

could it be related?


TIA

Check rear diff again. Mine "looked" perfect as well, but when you put pressure on the drivetrain,
 

the whole thing moved up and down by a few inches. Replacing it made the problem go away.

I'd recommend removing your rear diff mount and inspecting it
 

If it SEEMS ok, then replace it and drive around for a while - if it SEEMS done, replace it (expen$ive - $250 list).

A failing rear diff mount can cause loud clunks in the rear when going over big bumps on the highway (not the exhaust unless it doesn't have clearance). It will also clunk in 1st/2nd gear when getting on/off the throttle quickly under 3000 rpms.

It could of course be something else, but sounds like a rear diff at least to me - I'll post pics of my failed rear diff mount, hopefully tonight.

Re: I'd recommend removing your rear diff mount and inspecting it
 

<ul><li><a href="https://forums.audiworld.com/s4/msgs/1484518.phtml">Rear Diff Mount Install</a></li></ul>

i removed and inspected....
 

it looked perfect. the rubber wasnt damaged at all. it did however allow me to move the rear diff while installed (i was laying under the car)

is it supposed to let the rear diff move when i push it?

so how do u put pressure on the drivetrain while looking at the rear diff?

Well, I have a lift, but on ramps, just push up with your hand on the rear diff. Mine
 

moved a few inches up and down. The new one only moved about 1/2 inch or so.

I'm even considering getting another bushing/grommet (e.g. energy suspension) and putting that in there too to eliminate all movement.

yea mine only moves about a half inch, maybe 3/4

Yah, it's meant to allow for movement - tough to tell you what is excessive though
 

Any rub marks?