Movnviolation

89 Corvette! I just received my new Luk dual mass flywheel and Luk clutch assembly from Carolina Clutch today. When I ordered it, I was told that the flywheels are balanced at the factory, no need to balance them!
I have been chasing a vibration that is there sitting in driveway or driving since I bought the car. I have eliminated everything except the flywheel.
I had my six spd. rebuilt approx. a year ago. The D/M flywheel was surfaced for the second time. The trans shop said the flywheel looked good.
The motor was rebuilt just before I bought the car and has approx. 25K
on it since rebuild. The flywheel was surfaced then also.
My problem is on a Technical Bulletin that came with the flywheel it states "Remove the old f/w and place it beside the new one so the flywheels are in the same position. Install the new weights (included) to maintain the factory fine balancing!
An engine builder that I have used in the past, with a very good rep. said that the L98 motors are internally balanced. He said that the flywheel should come already balanced, however he could spin the flywheel w/ clutch assy. if it made me feel better.
If the flywheel was bolted up to ther rebuilt motor, there is no factory fine balance, so the weights on the old flywheel would have nothing to do with the balance of the new motor. If the motor is internally balanced, and the flywheel is balanced, why is there a problem?
I will spend money to have a nice driving car, but I don't think I will pull the motor so I can balance the flywheel to the motor!!

I need suggestions Please!

Redeasysport

The harmonic balancer?if the rubber between the 2 parts is cracked or broken Bingo! I know the LT1s are internally balanced but I don't think the L98's are they are balanced by the HB or as some call it the damper. I have had a similar problem with my LT1 and am replacing the HB tomorrow as I started it up with it off and had no vibration. I could be wrong about the L98 internal balance but if it is then the harmonic balancer is the trouble. Even if it is not it may still be the problem make sure if you replace it that the weights are in serted exactly like the ones you have on now are.If you know for sure the engine was balanced during rebuild then you need a zero balanced HB and the stock one may not be. There are after market HBs that have bolt on weights that can be adjusted till you find the right position for it to balance the engine out.

On the LT1 it is not really "internally" balanced it IS balanced by the flywheel and it cannot be replaced unless the same balance is made to the new flywheel.
http://forums.corvetteforum.com/show...13&forum_id=48

CFI-EFI

Read this thread.

http://forums.corvetteforum.com/show...13&forum_id=48

Your engine builder is full of beans. ALL 1986 and up Gen I and II engines with the one piece rear main seal are IMBALANCED in the rear. That thread should explain everything.

RACE ON!!!

Redeasysport

Beat you on this one EFI I even had the same link to the other one.

CFI-EFI

Yes you did.

Now, the $64.00 question is, was the engine truly, 100% internally balanced? Or was it internally balanced to factory, one piece seal, specs. Since you say it has always had the vibration, it doesn't sound like matching the balance from the old flywheel to the new, is gong to accomplish anything.

RACE ON!!!

Redeasysport

CFI could he balance it with the damper if the one he has is bad? Like I said there are aftermarket ones that are adjustable.

Movnviolation

What do people do that order crate motors, and get a new Dual Mass as GM suggest???
There has to be an answer here somewhere!

CFI-EFI

The front is neutral balanced. I don't have any LTx experience. As far as I know, any removable weights in the damper were factory installed for "fine tuning", probably even before it was put on the engine. Since we don't know how it was balanced when it was built, anything is possible. But since they all came neutral in the front, I can't imagine anyone screwing with that. If the old damper is OUT of balance, Yes.

RACE ON!!!

Redeasysport

I believe( But am not sure) crate motors come with damper on. In the old days the balance was done with the harmonic balancer/damper. What I said still holds true take your balancer off move the belt out of the way and start your engine if the vibration is gone you need a new harmonic balancer.

CFI-EFI

In the old days the balance was NOT done with the harmonic balancer/damper. All Gen I and Gen II small blocks have been neutral balanced up front, with the notable exception of the 400. The 400 was externally balanced, at both ends.

RACE ON!!!

Movnviolation

Solved my problem today. Left the new dual mass & clutch ***. with an engine builder and told him to put a new motor in front of it. I have been chasing this vibration for over a year and am sick of it!
He has a four bolt block and the heads. he will put rollers in it. He will get me what ever added H.P. he can by kicking the comp. a bit, and some head work. It still has to be a smog motor. He will balance everything. Be ready in about a week.
Thank to all for your input. I bought this car to drive and if I want to take off across the country, I want to do it with peace of mind.
Would not want to listen to the wife if it did not make it!!!
Thanks again!