I have a 1986 firebird. It seems, when I take off from a stopped position, the rear end hits the ground. This just started happening. I can feel the rear end hitting the ground and don't know, if it is the shocks, which I doubt or it is the torsion bar. Hopefully someone can help me with this. Thanks

3rd gens use spings, not torsion bars.

Is your car lowered, on purpose? If not could be worn out, sagging springs and worn out shocks. Or (most likely) a combination of both.

it's not hiiting the ground, your feeling a broken trans mount or something else, have some one watch you take off, and look for the rear hitting the ground, i can't imagine how it could happen, unless you lowered the car like 5."

you sure it isnt just hitting the rubber bump stops in the rear? hitting the ground seems impossible on a stock setup. but yeah, the springs would cause that, not shocks.

I think he meant the Tourque Arm ,not torsion bar.

Maybe, but I just responded to what he did say.

When the torque arm bushing goes out, the clunk domes from the tranny under acceleration/deceleration. Not from the rear.

Well, if his torque arm is broken or sliped out of the bushing it would rotate up and hit the floor. we really don't know what he is feeling or hearing. he could be misinterpreting the feel and sound.

haha how can anyone say that the rearend hits the ground? its BOLTED TO THE WHEELS! no way can it hit the ground... the rear can only be as close to the ground as the wheels keep it off the ground. what your hearing could be a bunch of things, sagging springs will cause the rear to be closer to the bump stops(which are solid hard rubber) but i doubt that unless your car can seriously SQUAT and hook on acceleration. things u need to check are the torque arm mounting point on the rear, and at the transmission. check the transmission mount, check the LCAs on the rear etc. shocks can bottom out but its doubtful. id say u broke something or the rear is bottoming out against the rear but im gona go with broken something.

slim but check the play in the u-joints on the driveshaft could be a worn /bad ujoint with enough play to cause the metal noise your hearing.

how much fender to top of wheel gap do u have in the rear? 4" or 3" or so?

My lowered truck was always bottoming out until I changed the rear shocks. One was completely blown.

As for your third gen, the first thing I would check is the torque arm mount on the transmission. When you accelerate, the diff rotates upward. If the mount is broken, the torque arm will rotate up and hit the floor.

For the torque arm to slip out of the bushing housing mount, the whole rear axle would have move backwards a few inches. If the rubber breaks, the torque arm should stay inside the metal "case" , meaning it couldn't reach the floor to hit.

The tranny case itself will break (where it bolts to) before the metal of the mount does, or the mount bolts themselves, which isn't very likely to happen.

Ya'll are spending a lot of effort in "defending" him against my explanation. WHY? All I did was respond to what he said, nothing more. Put more effort in a person's explanation of their problem, than others reasons of what might be the problem.

because a broken tranny mount is pretty likely. it has happened to a lot of people, including myself.

I see no mention of the shifter moving. When trany mounts break, shifters move side to side.

Brkemn tranny mounts make a noise beside the driver, shifter (T5) move side to side, not a noise in the rear of the car.

Been through that one before.

Maybe it has nothing to do with the torque arm.

Sorry . I didn't mean to sound like an a**hole.

Does he have a t5 or an auto? An auto shifter is bolted to the floor. You are correct, the noise will come from next to you. Some people (I don't know this person, so, no offense to anyone) will hear a noise and think that is coming from somewhere and that may not actually be where it is coming from! I am not saying the tranny mount is the only possible thing that could be causing a noise. Just stating that it is something I would check. I stated my opinion here, I'm done.

check your tranny mount first, i think that is the #1 thing that goes bad on these cars, because of the torque arm.

I first replaced my torque arm mount and it still clunked, then i got a new differential because i thought it was slop in the old one, but it still clunked under hard acceleration. I then check the tranny mount and that was it. Now under hard accel it is very smooth