Hey guys. I just finished my T56 swap into my 91 T/A and when I started it the whole car shakes bad. It's like a drive train vibration but not sure what would be causing it. It is vibrating with or without the clutch pedal depressed. Trans went in smooth and had no problems (should have know by how easy it was going together I would have problems) and torqued all the bolts, flywheel and pressure plate to spec. The clutch is a resurfaced centerforce with a stock LT1 flywheel that is also resurfaced, could that be an issue if it was not done properly? Any suggestions would be appreciated or if anyone has had this issue please help me out! I did try the search option but found nothing related to my issue. Thanks in advance.

is your motor stock sounds like a flywheel balancing problem

yea stock 305, one piece RMS.

I have to agree we did that once in a mustang (neutral ballanced flywheel) and had the same car shaking problems your experiencing, then we swaped in the stock flywheel and it went away.

I was doing a little research on this, looks like the stock LT1 flywheel has a counterweight which is approx 125g, maybe your flywheel is 180* out or something.

Checked the flywheel last night and the counter weight is not there. Just picked up a new to me flywheel and will install it tonight. I am sure that this is my problem but will let you guys know for sure. Thanks to everyone who replied in this matter.

Here is a pic showing the LT1 flywheel backside with the counter weight to give you a idea what your missing.