ok heres the latest problem with my car. About a month ago i was doing a set of 0-60 runs on city streets and my car was launchng fine. Then on my last run I was holding the brake revved it to probly 2000 then launched and had a really hard banging coming from directly under my center console. later i experimented with it some more and the banging only happened in first gear and only if i gassed it somewhat hard- like gassing it so it would shift into 2nd at 3200 rpm, also when it shifted into 2nd it banged the hardest but then it wouldnt bang in any other gear even if i shifted into 3rd at 4500. Well that was on my stock 9 bolt rearend that was badly dying and i just had a new 12 bolt rearend and a strange driveshaft installed and the banging is still happening. Anyone know why it would bang so hard in first?
seems like its when the motor is putting out a lot of torque is when it happens

oh and the car is an 89 GTA w/350 ,700R4, 12 bolt w/3.42

 

99% sure its the tranny mount, very common for them to break.

When torque is applied the back of the tranny and driveshaft will come up and hit the tunnel.

 

I secon that. I have changed mine two times in the last four years because of the same problem . Also, it is hard to see that it is messed up you look at it under the car, you have to lift the tranny to be able to see.

 

alright well ill need to get that fixed right away, also is it really bad for the tranny or driveshaft, im more worried about the driveshaft since its brand new? and for the part do i just need the 1 transmission mount which is like $21 throught Summit for a polyurethane 1?

 

leave it go long enough and your going to have a new air conditioning system

Mine was only broke for a few days before i got the new mount and it scraped up the tunnel pretty good, the yolk/driveshaft didnt take much damage tho. It is also a bit hard on the motor mounts when its lifting up like that.

 

Yep...tranny mount. I've torn two of them over the years and they always make a lot of noise. The tranny twists and the drive line hits the heat shielding..BANG BANG BANG

 

another vote for tranny mount, mine went a few months back, cost less then like $20 for a new poly mount, fixed the banging, and the car feels better under throtle to boot.