warped flywheel

[bluestreak9999]

What's the allowable amount of warpage on an ACT flywheel? My step height is spot-on on the outside edge (.610) but the inside edge is .615. Just wondering if this is enough to cause either engagement or slipping issues.

 

[BogusSVO]

That is cupped, all flywheels do that stepped or flat.

When you step on the clutch, the flywheel will flex, and after heating and cooling, it will take a set.

Since the step is supposed to be .610-.612 and you are on a taper of .003.

I would also have to think some of that taper is due to wear of the friction surface.

I honestly can not see a reason for .003 to make an engagement issue or a slippage issue.

I just ground a stock flywheel on a different brand import yesterday that had about .030-.040 wear from clutch slippage and abuse (blew off the friction material from the flywheel side of the clutch disk) But the clutch would still engage and the car would move somewhat.

 

[PieEyedPiper]

Here's a couple links regarding flywheel runout for varying applications:

http://www.dsmtuners.com/forums/cylinder-head-short-block/94672-flywheel-runout-spec-needed.html Tuners Link. ^^Dale's .003 assessment sounds pretty fair.

Flywheel Runout...? - LS1TECH This guy had the same oblong "runout" with a brand new flywheel.

FLYWHEEL RUNOUT

Maximum flywheel face axial runout? - Chevelle Tech


I've experienced both runout from poor machine work as well as pseudo-runout due to obstruction between mating surfaces.

From my own experience, it's important to ensure a very clean mating surface between the crank and the flywheel (duh), but here's the kicker: accounting for the loctite you just squeezed out into each hole/bolt.
I'll post pictures when I can, but you can clearly see what had happened to me and many others across the automotive world.
When using loctite, use a little as possible to get the job done because what can happen is the excess will get pushed out of the flywheel holes and seep between the crank and flywheel mating surfaces. This will cause an uneven mating surface that can be perceived as flywheel runout.
I don't have any comment regarding flywheel flex. It might also be worth calling up ACT to see what their view is.


OOOooo..
Gotta toss these in here whenever you can:

If there is a locating dowel, it will not be a rollpin on a flywheel. When torqued, the flywheel must be rigid to the crank, with no more than .0051" runout.