Okay, so my 99 FRC had my throw out bearing go bad awhile ago and decided to redo the PP/clutch/slave/throw out/ and added a remote bleeder. I installed a Centerforce DF 12" clutch, with the resurfaced stock flywheel. I researched the balancing issue on here and a few other vette/LS1 websites like crazy and almost went blind to realize that there is NOT a single correct way to guarantee the flywheel won't vibrate, cause some people don't have any problems others have multiple ones.

Well, we checked the balance of the flywheel and it was like 15grams off. We balanced the stock PP & stock flywheel as it was on the car and they read "0". We then balanced the stock flywheel & the CF PP and it was like 15grams off no matter how we clocked it. So we added a weight to bring it within a few grams of 0. The strange thing was that the weight was not directly opposite the stock flywheel weights. The Centerforce weights never seemed to spread out evenly on the balancer. In hindsight I think this lead to us putting the weight in the wrong spot.

Installed the new setup, absolutely positive the flywheel was located correctly, as well as the PP to the flywheel. Torqued as per the manual and drove it for a few months. It vibrated a bit above 3500rpm, but nothing crazy. I decided to live with it for awhile and just take it easy on the revs.

Last weekend I decided to try and fix it. Read a mountainous volume of material again and decided to see what would happen if I removed the weight we added to the PP. Put it on jack stands, dropped the exhaust, and opened up the inspection panel, and removed the weight. Surprise surprise it vibrated pretty bad. Left it for a couple days and did some more research.

Decided to see what would happen if I removed my 3 stock weights from my flywheel as well. I could only knock out two of them as the third is covered by the PP mounting tab. Ran it as it sat and all seemed fine, no major vibration like before, maybe a slight one up at high RPM's but very slight. Open headers sounded sweet. Drove it for a few miles at all rpm's and gears, fingers crossed my vibration problem is now cured.


Cliff Notes:

- Throw out bearing went bad, replaced clutch. Stock flywheel & CenterForce DF.
- stock setup was "0" balanced from what we witnessed on the balancer
- stock flywheel & CF PP was balanced and was off, so added weight to PP, maybe not
added in correct spot. This gave vibration at 3500rpm and above.
- Decided to fix vibration. Took weight off of PP, vibration all over rpm range.
- Decided to remove stock flywheel weights. Removed 2 of the 3 and 95% of the vibration problem is gone.

 

So it looks like on my car the engine assembly was balanced by itself and the clutch assembly was balanced by itself too. But, the stock flywheel & stock PP weren't balanced separately, they were balanced as a unit. So when I mixed the stock flywheel & CF PP it was screwed up.

 

Exactly what the GM shop manual tells us and connsistent with my experience.

 

Thats just the thing, it worked for you, worked for me in the end, but there are other vette owners that have done what we did and had nothing but problems. Go figure.

 

I have an 02 ZO6. I just installed a SPEC duel disk clutch and flywheel set up. Was hopeing that the stock flywheel didnt have any weights but,,, IT DID!

I took the STOCK flywheel and the new fly wheel to the machine shop.

Told them to balance match the new one to the old one. Installed the NEW stuff. NO VIBRATIONS!:smas h:

Bill