LOL i hear ya, this is super noob question but this wouldn't happen to be clutch chatter would it? Even though the is in or out and stopped or moving? This clutch has about 10 miles on it so far.... i thought of a perfect example of the vibration, it feels exactly like the pinion angle is wrong cuz it shakes the whole car....... only problem is no pinion to be out of angle

 

It's not clutch chatter; that only happens while the clutch is being slipped.

As to why the vibration goes away, remember that you're not feeling the vibration directly, you're feeling it after it's gone through the rubber mounts. The purpose of those mounts is to absorb vibrations, and when the mounts ability is overwhelmed you feel what comes through.

Have a good one,
Mike

 

The way I read it,the service manual clearly states that on a NEW flywheel install,on an existing engine,you do NOT transfer or install balance weights to the NEW flywheel.
Am I reading this wrong,or what?



The harmonic balancer,yes,but according to what I'm reading ,NEW flywheel,NO.

So it looks to me like the install was done correctly,and the vibration is being caused by an imbalance in one of the components of the new assembly-maybe the SLP flywheel doesn't match up,balance-wise with the Spec pressure plate?
Doesn't seem like it should matter,but apparently in this instance,it does...

 

The hard copy 2001 service manual clearly states that the balance weights must be transferred from the old to the new flywheel in the same relative locations. I cannot speak as to the electronic copy posted above.
This subject has come up and was debated before, run a search on "match balancing".

 

I feel your pain I had a big issue with balance on the LS6 unit I put into my car I had vibrations from 700RPM and up , I ended up using my original flywheel just had it resurfaced. and that fixed the issue... My flywheel had the added weights what a PIA!! After all troubleshooting and efforts to balance the new assembly was said and done I ended up pulling the clutch assembly 5 times

 

I have to install my SPEC SS Twin clutch soon!! I’ve seen so many people have issues with the install of this clutch that it makes me Ill. Some of the issues have been installation mistakes some not. I need to get this pre measurement thing laid out so that I can visualize how to do it correctly. Measure twice, install ONCE!

I already purchased the TICK Master and all the other new stuff to do this correctly.

When I do my clutch,,, I’m going MARK EVERYTHING on the OEM ZO6 clutch before I remove it. Then I’m going to take the OLD assy and NEW SPEC assy to the machine shop and have the balance checked on each clutch assy. Depending on what this show me, I will have to figure out what to do.

Right now, I have zero vibrations on my OEM Clutch/engine. If the old assy is significantly out of balance, I guess I will have to have the spec fly wheel off set to that grammage.

If there are balance pins in the old fly wheel, I can mark where they would have gone in new fly wheel and work with that known value if there are issues after install.

Ksths2

I would go back under the car and do some additional clutch air gap measurements and make sure that you measured the CURRENT air gap measurement correctly. Looks like the air gap is excessive. Getting an accurate measurement on TWO disks can be difficult.

Get a set of LONG feeler gages and use those to check the clearance across a large area of the pad and make sure that you take all the clearance out between the pad and pressure plate and fly wheel. Press the clutch peddle lightly and see if it engagement point feels different with the feelers installed. Then go back and see if you can get more feeler gage in the air gap.

IF,,,the air gap is not excessive, it is possible that you still have air in the master or slave as strange as that sounds. Some people have had luck applying a vacuum on the clutch reservoir and been able to pull additional air out. Might try that.

I would also take the clutch assy to the machine shop and check the balance. Your most likely going to find out that its out of balance and that’s your issue. Do you have your old clutch pressure plate/flywheel assy that you can use as a balance reference?

Only trying to help.

Bill

 

Update: Here's the latest, I drove the car for about 1/2 hour the other night and i've done some more research on the car and come up with its exactly at 2000 rpms and goes away at 2200. the weird part is i'm not 100% sure if its the clutch, could it be the DTE strut brace? i installed it exactly how the instructions say by turning the rods 3/4 turns once zero lash and it gears don't whine that i can tell but the vibration is there for sure. It reminds me exactly like a car with the pinion angle is off.
I'm in the middle of the Tick adj. MC install and we'll see what happens after that. I bet its the clutch assembly not balanced but i dunno. i took the inspection cover off and the clutch assembly looks beautiful with no visual problems that i can tell other than very little gap between the flywheel, clutch disk, and pp when the clutch is pushed in. aka not disengaging.... i figure worse case i'll take it all back apart and have the clutch assemlby balanced together.
On a side note, i'm trying to break-in this clutch before winter hits here in Iowa and the Spec instructions say to have 500 miles of stop/go driving..... my problem is with that is what do people do with race engines running this clutch? i mean, if you'd put 500 miles on a race engine it'd be worn out before the clutch was broke-in so are the truely 500 miles really that critical??
And one more weird question, could i break the clutch in with this vibration without causing any harm to stuff? (engine, trans, etc) Only reason i ask is as soon as its broke-in i'm taking it all back apart to put the heads/cam in etc and it'd be alot easier for me if i could wait and do it all at once?
Thanks for everyones help i really appreciate it.

 

Update: i released the tension on the DTE brace and drove the car, no difference and vibration is still there........ so i'm starting tonight to take it all apart again and having it balanced.......

 

Anyway you guys are starting to make sense about the stock flywheel after reading in my GM service manual you guys are correct about the corvettes cranks being externally balanced by the stock flywheel and so when any other flywheel is installed that it will throw the engine out of balance? It says the reason for the special flywheel in the vettes is due to the solid torque tube and rear end setup. I talked to a trusted friend that works in a machine shop and he looked at my stock flywheel and it does have drilled holes and mallory or tungsten slugs installed on the outside of it to balance it and said my stock flywheel isn't bad so he could just machine it flat or just take a .001 or 2 off and that way i could reuse my flywheel and the out of balance issue should be gone in theroy...... makes sense to me, what do you think?

i'm in the middle of taking it all back apart so i can try this idea, if it don't work i'll kill myself lol

have a good Thanksgiving!

 

I agree with your machinist friend.

 

It's really simple. Check the old clutchflywheel balance as a unit and note if it is off a lot or just a few grams, if just a few grams then Im sure it was ment to be zerod out as a package from the factory as they are not going to be as pi cky as the machine shop will be. Take the new flywheel/clutch combo to machine shop and have it zerod out or match the old setup if it was specially balanced to take out engine imbalance.

My spec 3+ and billit flywheel was 21 grams off 6" from centerline and most of the imbalance was from the pressure plate(18 grams). It did cause a vibration like you describe. I didn't buy the clutch/flywheel as a package as my friends didn't stock it that way, but spec does balance those package units as a assembly, but I'd rather check it at the machine shop anyway. I just removed weight from the flywheel to zero balance the clutch/flywheel as a unit as my 383 is fully balanced internally.

 

Ksths2,

Your approach to correct your imbalance by installing the original flywheel is one way of handling it. You could also have your machine shop friend match the new to the old if you see an advantage to using the newer flywheel.

I would like to point out, all LSx engines are designed to be internally balanced. External balance weights are corrections and not the norm. There are other engines designs that require special flywheels with built in imbalance that are part of the rotating group. Not the case in any LSx series engines.

All LSx series engines that come off the assembly line take a net zero imbalance flywheel and harmonic balancer. The flywheels may have areas of drilling that are not through holes. These drill locations are to correct the flywheel to net zero imbalance. If the engine has vibration after assembly there may be small weights added to the flywheel to correct it. The weights are various length pins with raised ribs that are tapped into one or more of the through holes drilled around the outer diameter of the flywheel just inside from the starter ring gear. These added weights are easily missed during a clutch/flywheel install if the installer is unaware of them.

I hope the best with your balance project and have a Happy Thanksgiving!!

 

Update: tomorrow night i'm taking the rearend out to put the remachined stock flywheel back in but i just noticed something strange before i took it all apart i was watching the clutch assembly with the inspection cover off and my wife was working the pedal from inside and the SLP flywheel was flexing from the pressure of the new clutch. this blew my mind, wouldn't that eventually fatigue the flywheel and evenually explode? i'm sure the stock cast one doesn't flex. Is this normal?

Oh and one more thing, when i put the new clutch in the i replaced the throw out bearing with the new one that came with the clutch and it looked identical to the one i took out. the weird part is, the little bit i did drive the car trying to dianose the vibes the TOB whines like crazy when driving and the pedal out in neutral it sounds like the TOB is bad. you know how it rattles and sounds nasty...... how can this new one be like that? the stock TOB i took out was shot and didn't sound that bad.

 

Aluminum Flywheels are not the best for street or strip applications. There real benefit is in road racing applications.

A light weight billet steel flywheel works best and helps shave off some weight.

 

Update: I ended up sending it all to Speed inc and Larry balanced it and it was 14 grams off but i just got it back and haven't installed it all again but i will and let you all know. Truthfully after seeing what they did to balance it i don't believe it will fix anything at all, so then what do i do.......
One other thing, i first time i installed this i put a new TOB in but it whines now and rattles when i shut it off worse than it ever did with the stock one. Should i not worry about it or put another new one in?

 

If you don't think the job was done right, then don't install the clutch system and send back to where you got it.

As for the Throw Out Bearing, it typically comes as an assembly (aka Clutch Slave) I use the stock 2004 Z06 slave in all of my installs and have not had any problems.

Not sure what slave you're using ? The slave is sprung loaded against the fingers of the pressure plate so you should not really hear any noises.

 

I agree with you that 14 grams ~.5oz/inch is within normal balance spec's and most likely will not change a thing. Have you checked the original flywheel for balance wieghts? If the problem wasn't there with the original system you will need to have the new parts matched to the old to correct it.

 

Check the pilot bearing. After all it's been through you may need a new one. I had a SPEC 3 installed several years ago by a great shop. When I got it back I had a vibration. They had it balanced and that didn't fix it either. The final solution was to mark the PP bolts 1-6 and add washers under them one at a time until the balance got better. Then 'fine-tune' it from there until the vibration was gone. In the end all it took was 2 washers under one of the bolts.

That was my solution, I hope yours turns out to be as simple.

 

The difference in the "hard copy" shop manual and "electronic" is very curious. The electronic clearly says no need to move weights.

 

They welded a washer onto the PP, i figured they would of taken material out of the flywheel. who knows maybe it'll work.
I'm still using the stock slave

Yes the original flywheel has drilled holes around it and looks like tungsten or mallory slugs have been pressed in a few of the holes on the stock flywheel.... So my question is, why is everyone so against putting the stock resurfaced flywheel back in? i mean as long as the gap is right why would it be bad?

Pilot bearing looks beautiful and needle rollers move smoothly. Hey ARKAY, to add these washers like you mentioned you surely didn't put the entire driveline back in everytime to test this did you? If not, how did you fire your C5 up without the electrical, brakes, O2 sensors back together? I mean, didn't your car get super pissed??