I've got a bad vibration coming from the transsmision area on my 84 trans am with 700-R4. I've replaced the passenger side balljoint, both endlinks, both struts, tranny mount, torque arm mount, and balanced the tires, but the vibration is still there. It seems to start vibrating at about 60, then gets real bad around 65-70. About a year ago, i replaced the ujoints and took the driveshaft down to a driveshaft shop to press them in. i think they balanced the driveshaft, but maybe not. What else could cause the vibration, that is if the driveshaft is balanced?

 

If it happened after you pulled the driveshaft. Your driveshaft is probably out of phase. You are supposed to mark the yokes and shaft when you pull it for alignment.

 

yeah, it was vibrating the same before and after taking the driveshaft out. I'm not sure if me and my dad marked it, but if we didn't, what can we do about it?

 

To rephase the driveshaft you would have to pull it out and keep trying different positions untill the vibration went away. I wouldnt bother thou since your problem was the same before and after.
I would make sure the weight is still welded to the shaft.