Trying to chase down a "clunk" sound

[Warbird]

I have a weird clunk sound coming from the bottom of my car somewhere. When I slow down for a stop, and the tranny downshifts from 2nd to 1st, I hear a "clunk" coming from somewhere under the rear part of the car. It's not the trans mount, I had a poly one put in last year, and I just had it checked out the other day when I had my new shocks installed [it isn't the shocks, because I had the clunk before the new shocks].

Here's another thing. My driveway is at an incline. When I put my car in reverse from park, the car will actually jerk for a second and then stop. But it doesn't jerk when on a flat surface.

What could be causing this clunk? A bad torque arm? Bad TA mount? Bade driveshaft? Bad driveshaft u-joints? A loose bolt on the torque arm?

[jking]

Could it be possible that it is just your limited slip "clunking" when you change momentum?

All of my LSx cars seemed to do that at times. Especially the manual tranny cars when shifting.

Did it just start?

[Warbird]

You know, I was thinking it might be the LSD, but my car only has 31k on it...and this is a loud clunk.

[jking]

You know, I was thinking it might be the LSD, but my car only has 31k on it...and this is a loud clunk.

That's usually the source of occasional clunks. A lot of the time it's just engaging and disengaging on inertia changes and it's nothing to worry about, but if it just started doing it, and if it's doing it all of the time, there may be a problem.

[Warbird]

I'll have the rear gear oil changed. Maybe that will help?

[RainMan]

Two things to check,
1) Worn "U" Joints. Free-play or movement in the driveshaft "U" Joints.

2) Check for Pinion backlash in the rear end. Backlash is the "free-play between the Pinion gear and the Ring gear.

http://www.drivetrain.com/ringpinioninstal.html


From: http://www.rps4wd.com/tech/RandP/backlash.htm
RING AND PINION BACKLASH.- The ring and pinion backlash refers to the amount of space between the meshing teeth of the gears. Backlash is needed to allow for heat expansion
As the gears operate, they produce friction and heat. This makes the gears expand, reducing the clearance between the meshing teeth of the gears. Without backlash, the ring and pinion teeth can jam into each other and fail in a very short period of time. However, too much ring and pinion backlash can cause gear noise (whirring, roaring, or clunking).

Hope this helps

[redline]

come on its an f-body, if your rear end doesnt CLUNK then somethings wrong with it!