Well I finished my install of my Monster 3.5 Friday. I read all of the horror stories about flywheel weights and vibrations. as you can see from the pic below my factory flywheel had weights. My aftermarket Lightweight FW doesn't have holes that match up to the OEM to even transfer the weights over.

Even if it did I'm not sure they would work because the lightweight doesn't have the same rotating mass as the OEM and so I don't think those weights would balance the engine the same.

Anyway I hope she doesn't vibrate when I fire her up. I called Mike Yeager who sold me the clutch and he said there wouldn't be be any problem and they never add any weights to their installs.

 

My '01 Zo6 had flywheel weights.

When I put a new LS6 clutch and zero balanced aluminum flywheel it had a buzzing vibration between 4k &5k rpm, then went away and came back strong towards redline.

Took the whole f'ing assembly back apart and installed the stock resurfaced flywheel along with the same clutch and it was smooth as glass again.

$.02

 

This may help..........

http://forums.corvetteforum.com/c5-t...ease-help.html


Make sure to read posts #9 and #13

Good Luck...

 

Post #9 doesn't apply because the manual for an 02 says not to transfer the pins.

As for post #13 I wonder if the OEM flywheel is zero-balanced before the factory installs it or if they use that final spin-up to balance the engine AND the flywheel because it isn't zero balanced. That would also account for why the manual says NOT to transfer the weights.

I think the mass of the OEM flywheel has a lot to to with the use of the pins.

For example 15 grams out of balance on a heavy flywheel would certainly cause more vibration than it would on a significantly lighter one.

 

The added weights in the flywheel are to correct engine rotating group imbalances, not the flywheel. The flywheels are prebalanced to net zero before putting on the engine. It doesn't matter how much the flywheel weights, it has no influence as long as the flywheel is balanced. The original added pins at the same radius and degree location will still be needed. If the engine was smooth before installing the new clutch, it will be a shaker by not transfering the pins or having a machine shop match balance the flywheel before installing.

Check your PM

 

I just installed a Spec Stage 2 Clutch,with the Spec Chromoly flywheel,and it runs smooth as butter,right out of the box.
There were no weights on the stock flywheel ,but there was an area on the back of the flywheel that resembles swiss cheese-balancing holes,I assume.
Maybe I just got lucky,but there are no vibration issues whatsoever,from idle to redline.
This seems to be a somewhat confusing area of Vette repair(at least to me) because the printed shop manual states that any weights should be transferred to the new flywheel,but the electronic version says do not transfer the weights.

And I had holes,so wtf are you supposed to do then?

I opted to trust Spec on this,made sure the index hole was lined up,and went on ahead with the install.
Had there been any weights,and had I moved them to the new flywheel,I'd have a vibration problem now-so like I said,maybe I just got lucky

 

That's how I read it.......

Good luck...

 

From all I have read, the engine is internally balanced. When you replace either the flywheel or harmonic balancer, they need to be balanced before you buy them.

 

Yes and no.

Yes it's internally balanced (and shame on LG Motorsports who sold the clutch/flywheel and said I shouldn't worry about weights after I called them with the problem, " we've installed many clutches and have never seen weights... The are ALL balanced from the factory, it's not the flywheel/clutch) ---

And No... It shouldn't be balanced before you get it. Zero balanced, sure... But your machine shop will have to install the correct imbalance in the new flywheel to match the factory issue.


As a side note, the Swiss cheese holes on the engine side are to balance the flywheel itself before being bolted to the crank... The dowel weights added are to balance the engine assembly. (per the GM engineer who supplied the factory clutches to the plant)

 

 

 

Okay got her buttoned up enough to start it this morning. All I can say is SMOOTH AS FREAKIN GLASS. In fact it was smoother then what I took out.

Now I Called Eric yesterday and everything he said made perfect sense.
So here is my SWAG as to why it didn't need the balancing.

During the removal I noticed that the firewall already had marks on it where the intake had rubbed it. I'm thinking the Torque tube has been dropped before. At that that point I didn't think much about it. Maybe gear work or who knows why.

After we get the clutch out we notice the clutch didn't look more than 5 or 10K milesd old. Okay so maybe the clutch was changed.


Now after talking to Eric and he said looking at the pic I posted that there was a significant balance issue to warrant the use of so much weight. So why no vibration now?

I suspect that when the Clutch was changed the Flywheel was too and who knows where they got the Flywheel from. Since my car had a vibration before (and I suspect the vibration caused my pilot bearing to go out) I would say that the Flywheel balance they put in didn't match what was in the car originally.

Well that's my uneducated guess and I'm happier than a Hobo with a ham sandwich.

Thanks to everyone for their advice and PRAYERS!!!

 

That is great news! Glad to hear it worked out in your favor..