I have an interesting issue with my Wife's '91 Camaro RS. If you take off from a stop kinda hard or have the throttle mashed from first to second you can hear a thud from the right rear. You can also kinda feel the axle move. Can't quite describe the feeling. Visually I can't see anything obvious. The issue has been around for about a year and has not gotten any worse. I have only jacked the rear up by the axle at this point. Sometime soon I will jack it up and let the axle hang so that I can move stuff around. By the way it feels I'm thinking control arm bushing. But I would think that it would feel weird over bumps too. It handles fine other then when under power.

 

Sounds to me like a trans mount.

Kevin

 

+1 on trans mount.

Don't cheap out on the replacement or you'll be doing it again (2 or 3 times in my case).

 

Chances are if its a bad trans mount, the gear shifter would move up and down during a real hard excelleration, due to the torque arm moving the trans up and down, normaly when you here a rear end thud, its either a bad u-joint or to much back lash in the ring and pinion.
hope this helps

 

You should be able to see if it's control arms or a panhard rod. Check the bushings by wiggling the arms by hand. If it makes a clunk, it's bad enough you should be able to wiggle them around.
Gears shouldn't just go bad out of the blue. If it's not howling, then i'd doubt it's that.
Tranny mount you'd feel in the shifter. Take off hard and hold your hand over the shifter. If it JUMPS up and SMASHES your hand, that's it. Otherwise, take off the LCA's and/or panhard and check the bushings.

 

Here's what I wrote in another thread a few months back:

https://www.thirdgen.org/forums/tran...erence-do.html


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I just did mine this week. Had an open 2.73 and went to an Ebay'd Zexel Torsen 3.42 posi.

With the old open 2.73, a full throttle start would kind of "wiggle" the back end. I can't really describe it. An open rear shouldn't make any difference if you have good traction to both tires. With the 305, I ALWAYS had good traction.

But, the posi definitely launched straight and true, so that was an immediate benefit I noticed on the drive home.
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I would definitely replace the trans mount first, even good ones are cheap and easy.

I never noticed a big thump, but the axle moving is exactly what I was feeling with my "wiggle".

The new rear end cleared all that up, but I did replace my transmission mount a few months later.

So, in my case it wasn't the trans mount, but we might not be talking about the same thing. And again, the trans mount is cheap and easy.

 

UMM What tranny do you have auto or manual?
If you have an auto the gear shifter will not move bc it is not mounted to the trans like on a manual.
I say if it a auto car then trans mount. Try this put you hand on the driveshaft hump right behind the pass seat and floor it you should feel it hit the tunnel if its the tranny mount.

 

Yes it is an auto. If my shifter was moving I would have much bigger problems!!! I'll have to get the car in the air and take a close look at the trans mount. I have already tried wiggling all the rear suspension parts. Nothing seems to move with it on the ground.

I just have to do more work at this point... I'll let you guys know. It's rainy here in Oregon and this car sleeps outside. I'll wait until the I have a dry day to work on her. (Need bigger garage to hold all my toys)

 

I bought my 89 with bad engine and tranny mounts. The tranny mount is easy, the engine are a little complicated, and takes a while.
I got engery suspension polyurethane one's. Mine is a 5 speed, but if I got over 1/2 throttle, the stick would lift about 3 or 4 inches. That was the first thing I fixed. At any rate now I can dump the clutch at 5 grand and I don't feel the stick move at all. Much better then even brand new factory rubber.

Kinda wish I had a pic, but I would recommend taking the bolts out of the track bars too. Mine were so rusty one broke, but 2 of them were about 1/2 the origonal diameter.

Make sure your torque arm bolts are tight, I know mine moves some. (might be why it's cracked)

 

tranny mount. jack under pan its completly seperated. new one is like 17$

 

Might want to check your engine mounts too.

 

I've had this same problem. Energy Suspension gets my vote too, even tho they now say to not use it on these cars, A few people have had issues. So order it, or AutoZone may still carry it, and compare to your original before opening the packaging.