I just purchased a Spec V clutch assembly and a new billet steel flywheel.
Are you supposed to have the clutch assembly and flywheel balanced as a unit? Everybody keeps on telling me that they can balance just the flywheel and pressure plate seperatly!

 

they do. they zero balance both.

Dave

 

Uh my local machine shop balanced them as an assembly... that's how you do it.

My stock clutch was 8 grams off so they made my new LUK stage-II the exact same amount of down to the 1000th of a gram in the same place. The car is great now.

When I first put the clutch in I had no idea about the need to match balance with C5's and I got a bad vibration... had to do it all over again, but all is well now.

 

Uh... I just saw that you have a cusom built 427... I'd hope to god that it's a zero balanced motor... thus having the components both zero-balanced should work fine.

 

The RPS unit I put in before I know had been balanced as a unit. It had colored paint marks on it. You match up the marks on the pressure plate with the flywheel and install.

I emailed the vendor I bought the Spec from and they recommended I have it balanced. I just want to make sure that balancing the pressure plate assembly and flywheel seperatly will result in a zero balanced matched unit.
I don't want to pull this thing apart again just becuase the clutch assembly was not balanced correctly.

 

I hear you... the oem style units (made by LUK) have guide dowls on the flywheel so the pressure plate can only be installed in one orientation. Also the flywheel has 6 bolt holes and a 7th guide hole for alligning it to the crank. It can all only go on one way. Now for the Spec I'm not sure... I'd sure as heck spend the $100 to have it all re-balanced.

 

I'm confused. I thought that the LS motors were all internally balanced and that the exterior components, like the flywheel, clutch, and harmonic balancer were all zero balanced.

Did I understand that you purposely set yours up with an inbalance equal to what you removed from the car?

If that's the case, then any new flywheel would have to be rebalanced to match the stock one.

Is that the case??

Need to know as I'm just waiting for the right time to install an aluminum flywheel I just bought.

 

From my understanding if you are running the stock block/rotating assembley you must match balance your new flywheel to the old.

 

Or you could just have your old flywheel re-surfaced and balance all as an assembly. Ther really is no need for a new flywheel. Just ask Cartek.

 

THE MOTOR IS SUPOSED TO BE INTERNALLY ZERO BALANCED FROM GM, BUT THIS ISN'T ALWAYS THE CASE! THERE'S NO WAY TO KNOW HOW YOURS IS.

Yes you should be able to put a zero balanced assy on the motor and have all be well, but it doesn't always work.

I had to unbalance my new clutch assembly to make the drivetrain balance out... it's a common thing in the LSX world.

 

All GM rotating components are spun balanced to less than .0125 ips (inches per second) individually and then the remaining light spot is marked (either by paint dot or part# so that the light spots on components can be offset to make it easier to balance assemblies. There shouldn't be any need to balance the clutch and flywheel as an assembly. Doesn't mean you can't, just you shouldn't see any real improvement if they were properly made in the first place.
That's my $.02

 

The Kid is catching on.. You speak the truth, young Grasshoppa!

 

That would mean that the "balanced" rotating assy is "matched" to the flywheel/pressure plate at the factory - at least that's what you've done by making your new clutch/flywheel as imperfect as the factory set was.

If the factory is not matching the flywheel to the rotating engine assy, then it's just pure random chance (whatever flywheel and pressure plate met your engine at that station) that an 8 gram (which is a huge amount I would guess) out of balance in your original assy cured your vibration after you had changed out your parts.

How was the original balance on the aftermarket parts before you rebalanced/matched them?

Did you actually put your car together, have a vibration, and then had to take the car apart again?

Not giving anyone a hard time - I really need to know if I can take used aluminum flywheel and bolt it in my car, or if I need to take the original clutch and flywheel and have the new flywheel, with the old pressure plate, matched.

Mike

 

who or what is catek?

 

Here is advice from someone who just installed the same clutch and flywheel myself. Remove old Clutch and flywheel. Put in new, your done. I had nothing balanced. I have no vibration even at 160mph. Your new clutch will sqweek everytime you take off. To fix this take car to track with sticky tires, then beat it within an inch of it's life. Now clutch won't make noise anymore.

 

worthless post

 

The factory does a final test balance on all 6-speed ars (from what I've learned) and if it's off they then custom balance the clutch assy (via the flywheel) to make it all right and smooth.

Yes, I actually installed a brand new LUK Stage-II assembly that was guaranteed to be zero'd out. Then I got a rather annoying vibration. That clutch eventually broke and my rear main seal started leaking.

The Corvette tech mis read the LUK instructions ( you have to torque the pressure plate to the aluminum flywheel at a lower torque b/c the alum is softer) he torqued the flywheel to the crank at the lower settings and the bolts sheared off.

Thus I had to buy a new clutch and he re-installed it all for free. After getting the vibration the first time around I did major research and learned my lesson. The second clutch went to the machine shop and got match balanced before installation.... all is now well and the car has been great.

It was an annoying, time consuming, and expensive lesson to learn. Problem is that you have no way of knowing how your car is. I mean you could take your stock stuff and find that it balances perfectly and you wasted $100 bucks, but to me it's worth it, b/c if you had to pay to reinstall the clutch again it'd cost a bunch more.

Another problem is the GM service manual changes from early years to later... in the early manuals it specifically says to note the location of the balance weights on the stock flywheel and transfer them in the same orientation to the new clutch assy... then in later manuals it says specifically not to transfer the weights and the install the clutch assy as is from GM b/c it's supposed to be zero'd.

Fun ****.

 

I spent $50 having my LS7 PP and LS2 flywheel balanced, to find out they were less than a gram off.

For $50, I would have them spun as a set and checked. If you've ever changed a clutch on a C5, it's not worth taking a chance to save $50.

 

let me tell you what a corvette tech and I discussed a few months back. Mind you he does JUST corvettes and seems very competent. I have done 99.9% of the work on my car and only brought my car in for warranty so I feel I am a good judge of competence. What he does is such:

He notes the spots on the stock flywheel that has weights on it. He marks those spots on the new flywheel he puts in. he does NOT put those weight on until after he test drives the car and noticed a vibration. THEN and on THEN, IF there is a vibration, he takes that black plastic cover off the front of the bellhousing (not the inspection plate) and inserts one weight at a time and repeats. With that said, my new LS7 setup didnt need any weights and I have no vibration or balance issues. Ditto w/ the LS6 clutch I put in last year. The way he does it, the H pipe does not need to come down every time you want to insert a balance weight.

Dave

 

We put a Z06 clutch, flywheel, p/p, master and slave in our Vert this Summer and my service manual did say to transfer the weights but I was advised not to. Worked fine- no vibration.