i had my rotating assembly balanced a couple years ago, ever since ive had some vibration. my car is in the shop due to the centerforce clutch disc breaking. i want to get it right before i have it put back together again. when they balanced my crank,rods,pistons , i remember having to take my flywheel down to the machine shop. but since then i have changed flywheels. im pretty sure the vibration is coming from the clutch flywheel area. i have a newer moser 12 bolt, really new dennys ds,and had the tranny apart a few months ago and inspected. i thought i read a while back that centerforce had balancing issues with their pressure plates , so im hoping a new clutch will help. they just resurfaced my flywheel today and i was talking to the guy and informed him the motor was externally balanced, he thought it was internally balanced. i guess my question is should i have the flywheel balanced or just hope a new clutch solves my problem?

kev

 

driveshaft

 

I thought the 350 lt1 crank was internally balanced also.

 

Kind of, it is offset balanced, meaning there is not a neutral balance on the flywheel. All LT1 flywheels (supposedly) have the same amount of 'offset balance' to counteract the way the internals are balanced. So having used another LT1 flywheel you should not have had a problem since this is a GM Standard. It could have been your pressure plate/clutch perhaps?

If it were to be the driveshaft, some people flip them 180º and this helps, or you can have it balance checked also.

 

thanks for the replys. im pretty sure the driveshaft is fine, its a dennys n20 shaft and i purchased it last november. the shop said the springs in my disc were all messed up and the disc was no good. i was on the interstate when all of a sudden the normal vibration tripled and i couldnt shift without alot of force, and alot of bad sounds. barely made it home. so maybe that disc was part of the problem the whole time. would anyone recommend getting the centerforce pressure plate neutraly balanced by itself and leaving the flywheel balance alone? i found a post in a search saying to check the 1/4 inch bolts by rear main , so im defintly going to do that while its sittin on the hoist without tranny. might have found a centerforce disc for cheap, so im considering keeping the centerjunk pp for now. kev