I'm replacing the clutch. This will be the 3rd in my ownership so that means this will be the 3rd known resurfacing of possibly the original flywheel. I'm trying to figure out if it would be wise to replace the flywheel. There are no apparent problems with it.

Is there a minimum thickness for the flywheel? I can't find a spec for this in my manuals.
When are shims required and how do I determine the thickness needed?

 

Get a new one.

 

Why?

 

The flywheel has been resurfaced twice, while it should state on the flywheel what the minimum thickness is, it's most likely getting thin. As it gets thinner it doesn't dissipate heat as well, and has greater chances for cracking, and possible failure. I don't know about you but I enjoy having feet, and this is not a place to cheap out.

A new one can be had for under 100$, so why not?

 

If it's still within spec, that would be why not and it's not cheaping out if it is. Given the quality of all of the other parts I've needed through the years, I'm not so eager to run out and buy a sub $100 (Chinese) flywheel considering the work involved to replace.

There is nothing on the flywheel that I recognize as a minimum specification. It is a GM flywheel.

 

I got a new Chinese flywheel since I could not find information about a minimum thickness spec. The Chinese flywheel is as thick as my original, at least twice resurfaced flywheel, from the face of the crank flange to the clutch face and the Chinese flywheel needs to be resurfaced right out of the box. Because of this, I would much rather use my original again if it is within spec.

So I'm back to my original questions, does anyone know the minimum spec for an original flywheel?
When are shims needed and how do I determine the thickness?

 

I believe I read in another post they are only good for one resurface then you toss it, there is no spec listed as far as anyone can tell.

 

An update, I ordered another flywheel from another vendor, having been led to believe it is of higher quality. It turned out to be the exact same Chinese flywheel, with the exact same problems. I won't name names until I know how they are going to handle it.

Some info that might help others:

The first flywheel came from Summit Racing, Perfection OE Replacement Flywheels 50-6527.
The Flywheel on the car since before I owned it, GM 14088671, cut twice, for two clutch job in my ownership.

The GM flywheel is currently .954" from crank flange to clutch surface, making me think it was about 1" originally. It weighs 23 lbs. The thinnest portion of the clutch surface is near the cast in counterweight, .64"

Both Chinese flywheels are the exact same .954" from crank flange to clutch surface. They are both the light weight version but I did not weigh them. They are about .44" thick on most of the clutch surface, getting as thin as .20" where they are machined for balancing (or imbalancing).

These measurements in mind, I think I'm just going to cut the GM flywheel again, if I can't find some decent replacement.

 

I don't do much for others, with regard to clutches. So when I need to resurface, I take it to a qualified shop ( the one I used has since retired, so I will be in the hunt) and let them determine if it can go another surface. Like you were expressing, why replace with new if there's no tangible gain?

McLeod is very likely able to supply what you need, but may not have exactly the same 16lb weight of the lighter third gen flywheel. Call, don't email.

Centerforce is another who can accommodate you. Talk to them. Don't go by what Summit shows, or some other crap. Just call, say what you're wanting.

Neither is in China, and neither should be under $100.

 

Got 2 more flywheels.

First, a Jegs 555-601257, advertised to replace a GM 14088650. It is just a rebranded Chinese V2022 but a good price for that particular flywheel. It is also .954" from crank flange to flywheel surface and it is .60" thick at the clutch surface. It also needs to be surfaced out of the box. So better on thickness than the other Chinese flywheels but still not worth replacing the original.

Second is a GM 14088650. No indication of where it is made but it is an actual GM part, with GM and the part number cast in. This is .965" from crank flange to clutch surface and .68" at the thinnest, also near the counterweight and it is flat. Still not really thrilled with the crank flange to clutch surface dimension as I doubt only .011" has been removed for two clutch jobs but I do not know what the original dimension was so I will probably use it. I'll check run out on it and decide.

I didn't contact Mcleod or Centerforce but I did ask Summit about SUM-700186-1 and they say that one is 1". It was actually measured by someone so I don't know how reliable it is. .954" is close enough that a worn out tape measure or low attention to detail can make it look like 1". Pretty reasonable price but it's also 30lbs and having it lightened to match would easily make it equal the cost of the GM flywheel. I don't need billet since it is for a stock engine that is not raced.