I converted to a T56 and Street Twin two years ago, and didn't match-balance the flywheel to the old flexplate. Just used the small counterweight and things seemed ok. I have a slight vibration at certain points in the RPM band (nothing awful, but you do notice it) and I think that I should balance the flexplate/flywheel assembly. The only problem is, I don't think I have my old flexplate. Do I need to pull my motor?

Thanks!

 

grab a stock one out of a junkyard or off the board and balance the flywheel to match that

 

well, if the motor is out of balance, you'll hollow out the bearings pretty quickly. your problem could bein the clutch setup itself, and away from the motor. stock lt1's are externally balanced and unless all of them have the excact same balance, you'd need to get it matched to your assembly. I'm not sure if ls1's are externally balanced or not.

 

Hmmm... interesting. I hope I can find my old flexplate. On the bright side, the car is approaching 10K miles on the current setup, so I imagine if any damage has occurred I've been driving with it for a while.