I have no answers, only that I have the same general question. I read through that long vibes thread and it seems that ~75% of people said that's life after you get rid of the dual mass (vibes at 3000rpm or whatever), that's why it was there. Another portion said they balanced it and it's smooth. The rest claim it's fine as is....hence the question. The real issue is, if the LS6 is externally balanced, then balancing the flywheel independently may or may not benefit the overall balance of the engine after you install it. In that case, I probably wouldn't bother.

 

I have nothing but conflicting information on this issue also. Specifically,

1. All the GM service literature indicates that the CTS-V LS6 is externally balanced.
2. CTSV154, whose opinions I consider "bulletproof" assures us that these engines are internally balanced.
3. When I exchanged my dual-mass for a UUC lightweight flywheel I got no new vibration.
4. Ewill at Lindsay reported once that the several LS7 setups he had installed in CTS-V all had added vibration.
5. Others, as indicated by Kevm14, have had mixed results regarding vibration.

I just don't know.

 

This seems obvious but maybe there's a reason it doesn't work in practice. Couldn't the old flywheel be measured for balance and that degree of "unbalance" (if that was needed to externally compensate for internal balance issues) applied to the new flywheel? Maybe the stock flywheels are all pretty much well balanced. But this probably isn't a reliable method for those who have suffered a dual mass failure or degradation, as that may change the balance; I wouldn't trust it inherently.

 

This is certainly consistent with the Servcie Manual admonition to mark the postion of the dual-mass flywheel upon removal and to put it back where you found it.

 

The place I'm going to have it balanced at said that they want the old fly to compare...so that seems logical.

He was really thrown that I wanted it balanced and afraid I would further unbalance it once it's mounted up.

I just don't want to go through the pain it the ass it will be to take it back out.

 

Maybe the answer is the amount of external balancing needed to balance the engine as assembled by the factory is very small. I mean...you could buy a brand new dual mass flywheel from GM (I know) and it wouldn't be balanced for YOUR engine. Yet the only thing you can possibly do is bolt it up. Perhaps it is one of those things you just lose from the OE factor specs of the car, to when you start replacing parts. But it probably isn't a huge amount of weight. I could speculate and suggest that some cars may already have engines that didn't need flywheel balance correct. But I have no data on this whatsoever.

And don't they say the same thing for front crank dampers, too? Put 'em back where you found 'em. Yet new ones have no way to know about your particular engine...

 

These engines are internally balanced. Here is some corvette info copied from a vette forum.

The LS engines are not externally balanced.
Much of this confusion is caused by:
1.Chevy zero balances the flywheel and pressure plates as a unit so the flywheel alone may not be zero balanced
2.Chevy refines the balance of Vette engines after they are assembled by pressing small weights into pre-drilled holes in the flywheel & damper as determined by spinning the engine as an assembly
3.Chevy did not refine the balance of Camaros so they will not have the small weights
4.New replacement dampers are zero balanced
5.Used dampers from a Vette may not be zero balanced if they still have the weights installed
6.Aftermarket flywheels are zero balanced
7.Aftermarket pressure plates are zero balanced

So here are a few chooses when modifying your engine
1.To change only the flywheel or only the pressure plate, match balance to the old value
2.To change the flywheel & pressure plate together:
•match balance an aftermarket flywheel/pressure plate as a unit
•when using a new Chevy flywheel/pressure plate, you can transfer the small weights or match balance

Other options include going back to a zero balance damper & flywheel/clutch by removing all of the weight or zero balancing everything, which is as good as a Camaro balance

 

Also, zero balance doesn't really mean ZERO balance. There is a tolerance. So if you install things that may be slightly out of balance but still within acceptable factory limits, you may feel a vibe. You could also get lucky and install something so that two items ,suck as a balancer and flywheel, cancel out each other and run perfect. Or if you install one of the 180 out, could cause rediculous vibrations.

 

Okay, so if I am buying a new flywheel & pressure plate "set" where can I get the "set" balanced? In other words, what kind of shop typically provides this balancing service?

 

Get it balanced. It isn't worth the frustration or the few dollars to at least have it checked. I will probably be pulling mine to have it balanced because of a constant noise that may or may not be caused by the clutch assembly. And I have spoken with some professionals that work with the LS engines and they have also stated that it is internally balanced.

 

So needs to be balanced then?

 

I would. On my old flywheel there was only one pin so it was pretty close to zero. As other people found in this thread the information is all over the place about some have issues and others having none. Mine really doesn't have any vibrations so it might be fine but I do have an odd knocking noise. And if I had known it could have been out of balance I would spent the money ahead of time just to put my mind at ease. After getting the clutch installed I started searching and found some where someone had gotten one and had it balanced it was off from zero a decent amount (12 grams comes to mind). I hope mine is out and my noise goes away if it doesn't I only have a month to argue with a dealer to get them to help me find the noise which has already been looked into before and not found.

 

Generally good engine machine shops can or there are places that deal specifically with brakes and clutches that can do it as well. It's really a craps shoot. Just have to call around.

 

Yup, I've found one that will do it for $60...just wanted to make sure it was necessary first.

 

bump so i can find it easy later.

 

The OEM assembly doesn't "have" to be checked for balance, but based on the info provided by ctsv154, it'd be a wise investment to have it checked and adjusted before installation. Any engine shop can balance a flywheel and clutch assembly.