My RS, I bought off my friend a week and a day ago, has this unruly clank/thud that's comes from my rear end whenever in motion. It feels like I'm getting corn holed by a toddler very time. Speed only increase the tempo and intensity of the thuds.

I'm unsure if it is the shaft, u-joint, or rear diff. I'm leaning towards the shaft.

Just want to bounce some ideas off before the weekend when Ill have a chance to dig into and see what's up/what to look for.

Note, just started today once I got to the bottom of my driveway. (Darn thing is hellaciously steep.) Heard a clank with a mild thud, almost like I bottomed out but I don't remember a dragging/grinding sound.

 

Sounds like something that happened to my RS, does it clank and bang when you shift the car ?

 

Put it on jackstands and look at it. Maybe on someone else's driveway.

 

Broke transmission mount or broke torque arm bushing or loose torque arm mounting bolts at rear end.

It looks like you have a 5 speed trans.. Does your shifter move up and down when you hear this clanking? If so it's for sure the trans mount

 

What happened to my car was the torque arm bushing broke. And the bang noise went away. Easy fix actually and only cost me $8

 

I think my shifter and boots shifts/twists to the the right. I was a little more concerned about getting up the hill and parked and swapping out rides to get to work. Lol
But I hear the clank come from behind my seat towards the trunk. And I feel it coming through the centerline of the car (front to rear). I does it when ever the shaft turns and only increases when in gear AND in motion. If it sits still, there's nothing.

I swapped the u-joint out three years ago when my buddy had it, but there is a 1/2 chance we put the shaft in right. (180 out if it's in wrong.) But I haven't felt anything vibrating or thudding other than my spark knock which I was going to fix later on that night by setting my timing. -_-

 

Put the car up on jackstands or ramps and get under it. Push up on tailshaft of trans, and try to move it up and side to side.. If trans moves any at all, your trans mount is bad.

Grab torque arm at front and shake it up/down, left/right. If it moves your TQ arm bushing is bad.

Grab torque arm at rear end and shake it, if it moves the bolts are loose.

Do the same for the driveshaft U joint at front and rear.. If you can move it up and down, it's bad.

Do same for lower control arms..

My guess is still trans mount ot TQ bushing.

As an out of phase driveshaft will only vibrate, and bad U joints makes a clicking kinda cluck when you accel

 

Alright. Thanks yall.

Should know what I'm looking for and pricing now.

 

Man, I've been gathering info from this site for awhile......usually right on point and now it's my turn to pile on with the general consensus. 100 to 1 odds that it's the rear tranny mount. I broke two in the first 5 years owning my 91 Firebird. If you look at how they are made, then it's easy to see why the glued rubber mount breaks. All it takes is a little load or brake/line locking the tranny for a friendly street race. Super easy to repair and there are some better, more robust mounts available for the 3rd. Gen f-bodies

 

Yep I have been using the same ES red ploy trans mount for the last 10 years. Much better than the weak little stock ones