Ok so the swap is done. Was really easy and straight foward but i have a problem.

My car has a pretty noticeable vibration at higher RPM's

If i sit with my car in neutral clutch in and rev it to about 3500 RPM's it shakes the higer you go the more it shakes.

If i am driving it and get on it at above 4k RPM's in any gear it shakes. In 1st and snd gear it is really noticable. I didn't have my flywheel balanced to my old flex plate. I figured i didn't need to since i have had my motor rebuilt and used different internals. (still externally balanced though).

Does each car get a flywheel/flexplate balanced to it's motor from the factory? The Flywheel i Used came of a 96 LT1 Z28.

Also will any machine shop be able to handle balancing my new flywheel to my old flex plate?

ANy other ideas what it could be? I am using a new SLP clutch, pressure pate, throw out bearing, and pilot bushing. I think i am going to order a new tranny mount too although that one looked fine.

Thanks
Shawn

 

LT1s are neutral balanced. I belive the flywheels are also keyed.

However I just rememberd that "Hoostie" on here had some weights fall off his and his car shook violently.
You might try to have it balanced but you shouldn't have to.

 

well i have been told that the flywheels are not neuatrally balanced.

The way i understand it is Lt1's are neutraly balanced in the front and externally balanced in the rear of the flywheel or flexplate. I know my flexplate has a big weight looking thing along the edge of it. Didn't really look at the flywheel though.

Thanks
Shawn

 

the flywheel has weight molded into the back of it..

I am in the midst of this swap too.. from what I can understand from this site, you can swap a stock flexplate for a stock flywheel since the standards are supposed to be the same..

This is a point of some debate though as there are numerous posts on it..

 

you dont have to..all i did was put a flywheel on, no shakin here
Marcin

 

Well F#ck. I wonder what it could be then? I have already ordered a new LS1 tranny mount. but i really don't think that is it. Maybe i got a screwed up flywheel or something. Could it be possible that the clutch or pressure plate is off balance? I know the SLP clutch/pp kit does not come with an alignment tool so do you think they could have just guessed and got it a little off balance? I am looking for any ideas right now. so please shoot me some.

 

From what I understand, the motors are neutral balanced at the front and externally balanced in the rear. The flywheel does have a weight on it, but it is keyed to only go on one way and should be within spec for your motor. I didn't have any problems with swapping from flexplate to flywheel with no balance matching or anything.

 

Should the flywheel still be in spec even if i have replace the entire rotating assembly?

Thanks
Shawn

 

if u changed the internals..then u should have gotten the flywheel balanced for the new stuff.

 

Well at that point i had a flywheel and was using the stock balance.

I just stoped by my shop that is working on the car and they are saying it is the clutch slipping. And that is what is causing the shuddring as the clutch try to grab and then slips. Normally i would say that is hard to believe but i can smell the burnt clutch pretty strongly. This is a brand new SLP set up. it was given about 400 miles to break in. I think it's probably what is causing it. I just wondered if anything in the car could have caused it to go bad. Also are the SLP clutches known for this problem?

Thanks
Shawn

 

Yep, GM weights the flywheels/flexplates for each motor, to balance the whole assembly. But it will vary slightly from car to car due to tolerances.

What you'll want to do is have your new M6 flywheel match-balanced to your old flexplate. I suggest finding a place that has one of the newer electronic balancers.

This should fix your vibe problem.

 

was wondering looking at your stats.. when the engine was rebuilt was it completely internally balanced?

If so you may need a flywheel with no weight, I believe that is how all the aftermarkets come as zero balanced..

 

no it was not internally balanced. Wish it was though. It is still balanced off the flywheel.

Thanks
Shawn