i have a nasty vibration that only happens when i accelerate hard. it shakes the bottom of the seat and the shift **** real bad. any help is greatly appreciated

 

sounds like a ujoint to me

 

how olds the car/ how many miles?

 

Yea, either a u-joint, or the drive shaft may be out of balance. Grab the drive shaft just behind the tranny, and try to move it. Go up, down and side to dide. If it moves ANY little bit, bad u-joint.


EDIT....
Then repeat at the other end of the shaft, near the dif.
If one is bad, replace both.

 

its a 1990 with 104k on it and thanks for the replies

 

Yeah, probably a ujoint. But also check your trans mounts. I had a Z28 that did the same thing while hard acceleration as well and it was the trans mount.

 

My neighboors truck does that too, but he doesnt know **** about anyhting mechanical so itll never get fixed.

Jim

 

if its the mount then the car should shake all the time, not just at accel

 

Nah, not with mine. When I was crusing speed it was fine. When I accelerated, thats when the shakeing began.