Last week had a SPEC Stage II put in the car. It vibrates the car when pulling out into 1st gear, the rest of the time it is fine. This is not my problem. When I got the car back, I installed spohn's poly trans. and torque arm bushings. Now, I don't know if it is from the clutch, bushings, or exhaust but the car has some vibrations.

Under load going up rpm range, it vibrates between 2400-2700 rpm. Cruising down the road between 55-58mph the car goes nuts. Whole car shaking. Slowing, speeding up, it doesn't matter. Now, these two are not in correlation with each other.

I looked at the exhaust today and the passenger header just BARELY hits the k-member, so I ordered poly motor mounts to fix that. I will have the tires balanced tomorrow. I am really wondering if it's the 10-bolt though? What do y'all think. Also, I might take the driveshaft to see if it's balanced. It's an aluminum one I bought years ago.

 

The vibration you get when you first take off is clutch chatter...does the same thing on my Spec stage 2. As for the vibration at speed I would undo the driveshaft at the rearend and rotate it 180 degrees and then reinstall it. See if that helps. If it doesn't then start looking elsewhere.