Last night i was test driving a potential project. (94 z28) and when i tried to accelerate relatively hard there was a bang that seemed to come from between the drivers and passengers seat, obviously from underneath the chassis. This also happened when i attempted to give it some gas and the auto trans attempted to shift from 3rd to 1st, as it had just gone to 3rd and the rpms were low. It shifted after the thud; but this is obviously a large issue. The sound/thud also happened multiple times during one particular acceleration from 0.

Specs:
170k miles.
Stock.
Auto Trans.

I know there is a low probability of anyone having had this issue before, but any advice would be appreciated.

Thanks for your time.

 

Check the tranny mount - sounds like its broken.

 

Would i have to take that to a shop to check it or can i do that myself.

 

Safely get under the car. Put a jack under the tranny, and start to jack it. If the tranny tailshaft lifts off the mount/cross-member, the mount is broken. With the jack supporting the tranny, unbolt the mount from the cross-member, and then unbolt the 4 bolts that hold the cross-member to the chassis. Unbolt mount from tranny. Reverse procedure to install the new one.

Very simple.

 

Like he said, get under the car and look. Check trans mount, then U joints, torque arm mount, pinion play, hardware, etc.

 

It was the trans mount. Thanks for the advice!