Ok, I've seen this brought up briefly in other threads, but there are still some parts that are unclear.
I bring this up because I'm about to put a Z06 clutch and Aluminum Flywheel combo in. I'm finding mixed advice on whether to transfer the old flywheel wieghts to the new one or not. And mixed reasoning as to why.

The wieghts on the flywheel, what are they there to balance ? The engine or the flywheel ?

Assuming they are there for the engine, and I should transfer them to the new flywheel. If I move the 8 grams(example) in wieghts from the steel flywheel, to a much lighter aluminum flywheel, wouldnt that greatly throw off the balance of the aluminum flywheel ? Sure, its still only off 8 grams, but thats a much larger percentage off to one side for the lighter wheel.

I hate not knowing the science behind soemthing :p Any clarifacation and explanation is greatly appreciated

 

Oh no, not this again!! And I'll bet those old threads won't pull up any longer..

The short version is the factory adds (or removes) weights from the flywheel to both balance it to itself, and occasionally balance the overall rotating assembly. It's not a cut and dry one or the other. That said, you can't simply "zero" balance the new flywheel, slap it on and expect "guaranteed" results.

I'll give you my take on it..

Mark the stock flywheel's position relative to the crank before removing it.

Take the stock flywheel to an experienced HP shop capable of determining the current "balance" of the flywheel as it now sits.

If it's zero-balanced, then do the same w/ the new unit. Have the new flywheel balanced regardless of the manufacturer's claims that it's already done.

If the stock flywheel is "out of balance", then make the new flywheel out of balance by the same amount, in the same position.

Mount the new flywheel to the crank in the same orientation as the old one.

Enjoy a car no more vibration-prone than it was when you started. The down-side is you've lost out on the opportunity to "improve" on the factory balance.. The up-side is you don't have to remove your entire driveline again to fix a newly introduced vibration.

You could also apply these balancing / marking techniques to the new pressure plate as well, assuming you had a way to properly measure and balance.

 

Unfortunately all the supposed 'High Performance' shops around me are clueless. Its either kids that only know how to bolt on cold air intakes and spoilers or 'get-r-done' rednecks that have never seen a new fangled corvette before...... I dont want to have to pay to have TWO clutch assemblies shipped around

 

I can't give you a definitive answer, but I can share my clutch nightmare experience with you.

I had the LUK gold w/aluminum flywheel put in at a Dallas area shop. I had a bad vibration problem. I took it back to them and they claimed "normal for an aluminum flywheel". After another 2 weeks of driving, I took it back and they pulled out the clutch assembly and had it zero balanced. They put it back in and I still had vibration issues. Again they claimed normal for aluminum flywheel, etc.

I figured my problem was due to them not match balancing the old assembly to the new clutch assembly. I figured I was SOL, stuck driving a vibrating POS until I could have the engine pulled and zero balanced, or buy a new shortblock.

As a last ditch effort, I took my vette to LG Motorsports for their opinion. They drove it and agreed there was a major vibration. They tore it down and within 2 hours they had the problem identified. Their diagnosis was a botched install that lead to the pilot bearing becoming trashed due to the driveshaft not being installed correctly. A new pilot bearing went in and they replaced the driveshaft. Zero balance issues since.