opel

I would rather have the shims and not need them then need them and not have them. And I figured I could sale them If I did not use them.

Make sure the machine shop that balances the clutch know not to zero balance but to match balance it to the old clutch. I had a little trouble getting the shop that does my machine work to under stand that.
Mark the old clutch/flywheel how they went together and how they were mounted on the crank, and make sure the machine shop also marks the new clutch/flywheel as well so you know how to put it on the crank.

huesmann

I don't think you need to take the clutch to the machine shop; just the flywheel and pressure plate. The clutch position changes after every shift, so there's no way to include it in the balance. I guess you could have it checked for its own intrinsic balance, but I don't know that there's any way to weight a regular clutch disc.

opel

That's correct just the pressure plate flywheel and bolts.

dixieCorvette

i noticed that the old flywheel had random holes drilled into it? Does this mean it was balanced from gm and I have to do the same thing to the new flywheel?

Bill Curlee

ALL GM FLYWHEELS are zero balanced from the manufacture. HOWEVER,,,,,,,,,,,,,,, If that flywheel was used on a MN6/MN12 C5, It was HOT BALANCED at the factory with the flywheel, pressure plate and disk ON THE ENGINE! If further balance was needed, small pin weights were installed into the holes on the outside ring of the flywheel. The dampener was also hot balanced.

SO,,,,,,,,,,,,,,,, Your OEM flywheel is UNIQUELY BALANCED to YOUR engine.

If you install a new GM or OEM flywheel on your engine,,, You may expierence unwanted vibrations in the 1200-3000 RPM range.

Have your new flywheel matched balanced to the old one. Hopefully you matched marked the old flywheel to the position where if came off the crank flange. Some cars came out of the process not needing any additional balancing weights. In that case, a properly zero balanced flywheel should work excellent.

Here is some light readong for you to enjoy:

- C5 Clutch Vibration Issues: http://forums.corvetteforum.com/c5-t...post1585950971 C5, C6, C7 HOT BALANCE See time stamp at approx 8 min: http://gmauthority.com/blog/2014/12/...engines-video/


Bill

opel

Yes the holes are form the factory balancing and it looks like there is a pin weight in the bottom hole in the picture. As Bill said I hope you marked the position of the fly wheel to crank and the pressure plate to fly wheel before you removed them from the car. The machine shop will need to bolt the fly wheel and pressure plate back together for balancing.

Bill Curlee

I just want to clarify what I wanted to say. I don’t believe GM makes their OWN flywheels. They have a supplier that provides them flywheels. That provider ZERO BALANCES that provided flywheel to a GM spesfied finite zero balance. That supplier drills those large shallow holes on the back of the flywheel to make that supplied flywheel zero balanced. I do not believe GM drills those large shallow holes in their hot balance process.

For most GM supplied engines, that flywheel manufactured finite zero balance works just fine.

GM also internally balances the LS engines So, installing a zero balanced flywheel works in most all cases.

However, GM found during early testing that the C5 LS engine drivetrain utilizing a manual transmission had driver felt drivetrain vibrations caused by minor clutch component out of balance conditions where as NON C5 (F BODY) manual transmission cars did not notice these vibrations.
Probably has a lot to do with the torque tube.

SO, all GM C5, C6, C7 ect manual transmission cars, go through the EXTRA HOT BALANCING step where the small balancing pins are added to the flywheel outer holes to get the engine and clutch rotating assembly that much closer to perfect balance to eliminate that driver felt drive train vibration in the Y body line.

Bill