I've done tons of searches, read literally hundreds of posts and read the service manual over and over.
My question is what really needs to be done with the flywheel "weighting" that was done on some of the cars around 2000-01 or so? I'm beginning to think nobody knows the real answer! Does anybody actually know for sure....real world knowledge?

The way I read it, in my case, regardless of whether or not my factory flywheel is weighted or not.... I'm going to take everything off the car, have my new complete ASSEMBLY balanced (new FW, PP, clutch), and bolt it onto the car. When replacing everything there is no need to worry about factory weighting etc correct?

From the service manual:


1)Existing flywheel, clutch, and pressure plate assembly onto the existing engine: Flywheel position must be marked prior to removal and installed to the original position. Refer to Engine Flywheel Removal .
2)Existing flywheel, clutch, and pressure plate onto a new engine: Remove balance weights, if applicable from the flywheel.
3)New flywheel, clutch, and pressure plate assembly onto an existing engine: Do not transfer or install balance weights.
4)New flywheel, clutch, and pressure plate assembly onto a new engine: Do not install balance weights.

 

What model year service manual are you copying from? I have an 01 OEM service manual and it directs to transfer the balance weights to the new fly-wheel (if applicable).
I followed the service manual procedure and had no issue with imbalance.

 

Actually I'm using a cd manual. I am using the VIN lookup though for what its worth.

 

Could you mark your crank and old flywheel before removal. Than take the old fw and new fw and have the balance matched old to new? I guess transfering weights if present would do as long as you clock everything correctly.

 

Yea. I could certainly do that. The whole purpose of this thread though is which way is really the correct way?
Ipuig- Any chance you could do me a favor and post the process listed in your manual? I'd really appreciate it.

 

I'd rather not type up the procedure, it is quite lengthy and I do not want the responsibility if something goes wrong with your installation. If you are installing an aftermarket clutch I don't believe it will be of value; you should probably consult the clutch's manufacturer and seek their recomendation.
I installed the LS6 clutch, so the OEM service manual procedure worked well for my application.

 

real world.... well thar changes everyday

but the factory did balance some clutches after the clutch and flywheel were installed, that is why they want you to mark the flywheel with the crank.

i put an aftermarket dual dsik clutch with aluminum flywheel and it worked perfect

i do not recommend any OEM clutches if you are going to track the car.

stock clutch has an automatic adjuster in it that can't handle repetitive redline shifts

 

I would not balance with the clutch disk installed, it will clock every time you use the clutch anyhow.

I was under the impression that the only cars that had the non-zero balance issue were Z06's. I installed a zero balanced Tex and have not vibration issues whatsoever.

 

1) If you have the wieghts, the new flywheel needs to be balanced to match the old one. this can be done by transferring the weights, or dilling holes into the new flywheel.

2) The weights are added at the factory to externally fine tune the balance of the engine. The LS1/6 is not the only engine that is balanced externally by the flywheel!

3) If you had the weights, and do not match the balance of the new flywheel, you are undoing what they did at the factory to better balance the engine!

4)The reason why not everyone has the problem is that either:
A) Their factory flywheel did not have the weights.
or
B) The resonant frequency of the imbalance (which is due to not balancing the new flywheel properly) is not within the rpm range of the engine. However, the fact that the engine is not balanced as well as it used to be will most likely cause excessive wear on the pilot bearing, and who knows what else.
or
C) They got their new flywheel balanced to match the old one, and marked the flywheel's position on the shaft.




I don't think you will find anyone who has matched the balance of the new flywheel to the old and had vibration issues given they marked the FW position on the crank.

 

I have real world experience with this (unfortunately). Everything SaberD said is correct. Your engine's internal rotating assembly, harmonic balancer, FW, PP, (and sort of clutch disc) are all a complete balanced assembly. If you like your factory balance and want to maintain it when doing your clutch job, you need to replace whatever components you remove with components that have the SAME state of balance. If your FW is zero balanced by itself from the factory, then replace it with a zero balanced FW. If your FW has weights in one or more of the 12 equally spaced circumferentially located balance provision holes, then you need to match that state of balance (most easily done by transfering the weights).

STATEMENT: The most certain method to ensure you keep your factory engine balance is to take your stock FW, (disc), and PP together as an assembly and have a shop "weigh" the assembly. It will either be zero, very close to zero, or some amount of imbalance. You need to have your replacement FW, (disc), and PP MATCH BALANCED to your original assembly. If the assembly is anything other than zero balanced, you need install the new components in the SAME ORIENTATION as the original components. So you need to mark or scribe the FW's position to the crank. This will maintain your original factory balance. I know my year service manual says this, and I believe all of them do as well.

I would challange ANYONE to refute the validity of that statement! I don't care if you do or do not believe in the "magical mystery of FW balance weights", following that procedure will maintain your factory balance. Physics dictates as much.

Now, the FACTS as I have discovered through research: I have consulted many sources but the most "officially authoritative" consist of GM engineers and GM engine builders from the Wixom Performance Center.

1. The FWs and harmonic balancers come to the engine builders having been balanced from the supplier. The engines are then "final balanced" by installing weights in the harmonic balancer, the FW, or both as needed. They balance each end to within .5 oz∙in. This is known as dual plane dynamic balancing, and is very common in balancing ANY rotating assembly outside of the automotive world. So some would need no weights, some would need some in the balancer only, the FW only, or both. They told me the most they have usually had to correct for at one end is about 4 oz∙in.

2. To those paying attention, you may have noticed I said "Wixom performance center". That's right, they build the LS7, LS9, and dry sump LS3... They STILL use this balancing procedure with the NEW engines as well, it's not relegated to C5's, or even only a certain number of C5's. Now that's not to say that some years were more "out of tolerance" to begin with than others, and not transferring weights resulted in a physically more noticable vibration than others, but that is pure specualtion and frankly irrelevant.

You will find a vast number of "opinions" on to what should really be done, but the fact of the matter is, there is AN ACTUAL PROCEDURE USED from GM to build and balance these engines. Once you know that, who cares how one wants to interpret which version of the service manuals. Mistakes are often found throughout.

Specifically to the OP, mark your FW before taking it off, check for balance weights, if you have them, transfer them to the new FW and replace in the same original orientation.

This issue and its unfamiliarity among all the "experts" (dealerships, performance shops) really irritates the crap out of me.

 

Chill, its just a forum on the internet!

 

That statement was not necessarily directed towards the comments from this forum. It was more directed at the 15+ dealerships I contacted, numerous "vette shops", clutch manufacturers, and tuners, that all had different levels of understanding/misunderstandings, "beliefs", and a general unwillingness to even consider the possibility there was something they didn't know about this issue. Admittedly it has frustrated me immensely, but not from the contributions of this forum. In fact I have been able to be in contact with quite a few forum members who have been very very helpful in my getting towards a resolution.

I have found this forum to be full of good people who are more than willing to help.

 

Take the (disk) out of your statements and then I'll with what you said. The best thing to do is to have a shop match the new balance to the old balance and install in the same clocking just like you posted. If the engine was good before then it will be just as good after.

You can't bolt a clutch together on the bench and get the disk centered. It's even easy to get it off a little bit when you are assembling it on the engine with an alignment tool. Then, the first time you use the clutch the disk will turn relative to the flywheel. If you are concerned about the balance of the disk then get it zero balanced seperate from the rest of the clutch assembly. GM may have balanced the whole assembly when together but they must then have had some way to center the disk and they were also assuming it was balanced.

Peter

 

Two questions on this.
#1 If the items need to be balanced together to match the old setup by a shop, what do those of us that dont have a machine shop within a hundred miles around do?

#2 If we change to a lighter flywheel will that mess anything up since it was all originally balanced with the factory one?

 

lionelhutz, I completely agree. I put the disc in parenthesis to try to imply " maybe you can include this too". If I left it out, someone would have come on saying "what about the disc???"

The disc is almost never in the same clocked orientation to the other pieces, as it can rotate independently of the others.

I'm glad you agree.

As for the question of less mass being placed at the plane of the flywheel, in the case of a lighter FW. Yes it would change overall dynamic balance, but probably to a much smaller degree, as many have put on lighter FWs with no "noticeable" vibration problems.

 

Keep stock and transfer the weights.

If the balancing weight is placed in the same location then it will work just as well on any flywheel. Consider the balanced part of the flywheel as a holder for the weights.

Peter

 

good to know,

I am going to need a clutch soon so I have been researching all of this balance stuff. I called the GM dealer and they had never heard of this. The local corvette shop said that they dont worry about it. The one clutch that I personally helped put in (Z06) was just out with the old and in with the new. The only other clutch I ever dealt with was on a C3 externally balanced 454. On them GM didnt fine tune anything. They all got the same balancer and flywheel. I am still finding it hard to believe that a mass produced engine got the time allotted to fine tune the balance on it but who am I to judge?

 

1) ship it to a machine shop

2) the flywheel without the weights should be zero balanced, and the weights are used to balance the vibrations coming from the engine. Since the fw is zero balanced, it does not have an effect on the balance of the engine. therefore, you can change to any weight of flywheel you wish, and the exact same balancing mechanism is in place when the weights are transferred.