Can someone tell me if the flywheel in clutch kits are already balanced. If not, are the f/w and pp balanced together? Thanks for your input. Jim

 

If its OEM and you bought the whole Assembly together then yes it comes all balanced together. If its aftermarket call the company and ask for a no guess answer.

 

Thanks for the input. Jim

 

Jim, please be VERY VERY careful when installing a new clutch/FW setup in an early C5 like your '99. You may know, many of the manual trans engines were final-balanced at the factory by installing lead weights into various holes in the flywheel. If this was the case with yours, and you install a perfectly balanced new unit, even a GM OEM part, you could end up with a pretty bad vibration issue. This happened to my almost-new 2000, and the dealer ended up removing and replacing my Clutch/FW 3 times before they finally called a factory guy down to externally balance the unit.

There are tons of data on the forum, plenty by me, that explain the issue.
bottom line: MARK THE POSITION OF YOUR PRESENT FW ON THE CRANK BEFORE REMOVING IT. Then look for the lead weights. If you have any weights, they must be installed on the new FW in the exact same position relative to the crankshaft. If you install an aftermarket clutch/fw, same thing applies - may be best to balance check the new unit and the old FW and MIS-BALANCE the new unit to match the original one.

Many guys have gotten lucky on this and did not have an issue - but if you do then it can be pure Hell to resolve after that original FW position on the crank is lost.

Please do a search on the topic!!!!!!!!!

Cheers,
DG

 

Very interesting!!!!! I'm a "little" handy around drive trains. But this issue is way over my pay grade. Are you saying the original f/w is balanced with the rotating ***'y? In which case all f/ws (in my case) have to be done the same way. Could you lead me to somewhere I could look into this further. My wallet won't allow me to do this more than one time. If I end up with a vibration it's I'll be bouncing off walls.
Thanks for the info, Jim

 

https://www.corvetteforum.com/forums...checklist.html


Mr. Sam

 

Take a look at the link above, but yes, the flywheel balances the engine. When you pull the OEM flywheel you need to remove the small weights mounted around the edge of the flywheel and transfer them to the new flywheel, in the same location. Line up the flywheel bolts pattern to orient them in the same spot.

When I bought my 99 FRC it came with a newly installed LS6 clutch. It was the first Corvette I had over owned and even though it was bone stock it had a fair amount of engine vibration to it. I figured it was normal. After I installed my cam the LS6 clutch wouldn't hold, so I had to replace it with an LS7 unit. I do most of my own work and when researching the project came across this flywheel balancing topic. When I removed the LS6 clutch the flywheel had NO weights. Huh. I took my new LS7 flywheel and clutch to a local clutch shop (South Bend Clutch - a pretty well known outfit actually) and they balanced the two units together, indexing them with paint marks for me. That's how I installed the two units and after I buttoned it all back up the car idled almost like my DOHC V6 Explorer engine. Even with the cam in it the engine was smoother than with the old, completely unbalanced LS6 clutch.

If you have weights, move them to the same spot. If you don't, at least balance the assembly you're about to put in.

This is a real thing. Take it seriously if you don't want to be annoyed after your clutch job. ;-)

Kurt

 

Guys, thanks for the additional comments.
Jim, for more info on the subject, just search "flywheel balancing", "engine vibration", etc; or even under my tag - "'the wrench". I was a pretty strong advocate for checking and being careful of this pitfall after the nightmare I went through back in 2000. I think i was the first "poster boy" for this - my dealership didn't even know about it, even though it's covered in the 2000 service manual.
It seems that the vast majority of the later C5's rarely had noticeable imbalance issues, and really, most of the early ones didn't seem to have either. But every once in awhile one of the guys would get the noticeable vibration after a straight clutch/fw swap.
I guess there might be 3 possible approaches to take, depending on how lucky you feel:
1. Just pop it in and hope for the best - pretty good odds you'll be okay, but........
2. Assume the new unit is zero balanced okay, but carefully inspect the old FW for the weights, and if you find any, pull the weight and add exactly that much weight to the new unit in the exact clocked position relative to the crankshaft.
3. take the full monty approach: have the old clutch/FW balanced checked. have the new clutch/FW balanced checked. If the old unit had imbalance, then unbalance the ne unti the same amount, AND BOLT IT ON THE CRANKSHAFT IN THE EXACT SAME CLOCKED POSITION, so the imbalance is located exactly the same relative to the crank.

I think most guys herein have used option 2 with success.

DG

 

The hot balance procedure is real. Here is a good article on a dry sump LS3 build at Wixom. Pictures 27 and 33 reference the balance procedure. Pay close attention to the order of operations, and what all is installed BEFORE the balance procedure is done. Hopefully that will shed some light on what is actually going on. The balance procedure accounts for imbalance made up from ALL the engine/FW/clutch components. Not just the FW. Not just the FW and engine. Not just the FW and PP combo (as many think). It accounts for ALL of them. So trying to match balance the FW only, by transferring balance weights, is a partial approach, and not very accurate.
"STEP 3" from Wrench is the best method to assure you have the same balance as what you started with from stock.

Check it out:

http://www.superchevy.com/how-to/vem...uild/#photo-33

and YES, this is the same procedure that was done for manual transmission C5's .

 

EXCELLENT INFORMATION and a VAST knowledge bank on this issue!

It all boils down to MATCH BALANCING your NEW clutch to the OLD OEM assembly and making sure that you get it clocked back on to the crank in the SAME ORIENTATION!