Warped clutch floater/pressure plate and uneven disc wear

D

disquek

Well-known member
This disc as well as the rest of the clutch assembly was new at the start of 2011. The flywheel was newly resurfaced. I ran 6 races on it.

The only notable wear on the disc is on the outer edge. The floater/pressure plate is warped badly (about .050). The flywheel seems fine. I put a a straight edge across it in several places and I couldn't get a .002 feeler gauge in the gap anywhere.

I think that the warping explains the uneven wear. But why did it warp?

The clutch is a 7.25" Quartermaster single disc v-drive. It has the aluminum fulcrum and the red springs. Nothing too fancy.

IMG-20111228-00016.jpg


-Kyle
 
Just a thought. Are you sure the ID of the pressure plate or flywheel or contact area is not larger than the contact area of the disc. That wear area edge seems to stop at a very fine line to be due to warpage alone.
 
Hi Gary,

Thanks for the thought. Yes, I'm sure. It's all standard 7.25" stuff.

The flywheel, PP, and disc all show light wear marks in the inner area. It must have warped soon after being installed.

-Kyle
 
I used to see this all the time.
Time to buy a new floater and have your flywheel resurfaced.

The floaters get hot and eventually and warp. You should be able to see it with the naked eye. The floater was already warped the last time you replaced the clutch disk.

This is nothing major or new.

Peter
 
Peter,
Is six events really a normal lifetime for these things? Wow!

Al,
Uniformly belled.

-Kyle
 
Lay a sheet of 400 grit paper on a flat surface (glass table if needed) and rub lightly to see the pattern on the floater. They will cup and kill the clutch disk in a weekend because only the outside 20% is doing anything.
 
I agree with Peter we run the quartermaster and burned a set of discs a couple years ago talked to the local race shop and they recomended replacing the set (discs/floaters) since then we had no problems (15+ races), the floater may be heat stressed and only show warpage under high temp, for the cost I would replace it.
Just my .02 worth
 
The floater/PP is certainly warped (as noted in my first post) and will be replaced along with the disc (at minimum).

What I'm asking is why did the floater/PP warp in the first place? Bear in mind that this stuff was all brand new (everything) at the start of 2011.

-Kyle
 
I have always used the QM double or triple disc clutches. Never had a problem with them. And usually got 8 years, or more, use out of them. Because they lasted so long I never considered them expense, just very durable. Like good rods and cranks, the expensive stuff is cheaper in the long run.

Was always careful not to ride the clutch, treat it like an electical switch, on/off.

They may not be as forgiving for mismatching RPM's to downshifting.

Do you have the correct size clutch master cylinder and release bearing? And the correct clearance for the release bearing. It may need some shim adjustment.

Peter is correct, replace the discs/floaters and polish or resurface the flywheel. I would sometimes remove some of the flywheel burn marks by lightly polishing it clean with 400 grit wet paper on a block sander. You may want to measure run out of the flywheel, after it is cleaned up, to insure it is not machined off at a very small angle, not truly flat. Then check the release bearing clearance and actuation. It should last a long time when set up.
 
I've had that same problem with them, took it out and it was so concave you could eat soup out of it. If you go to their web site and read up on them they say heat is the problem.
 
Sorry not trying to hijack this thread, but this ties into the pressure plate issue. I know that he stated that his was new, but has anyone ever had their PP re-ground? Tilton statest that they can be ground as long as the min thickness is not exceeded, (0.525").
 
Verify that the flywheel grinder head passes all the way across the disc. The machines that stop in the middle will produce a curve.
Face the PP , on the same machine.

Dont drive the car onto the trailer.

Verify room to engage completely by about 030. ( disc center to flywheel ,bolts etc. ).
I use clay to verify set up engineering. It not uncommon to have some pressure on the edge of the disc,as the hub bottoms against something. The re may be very slight marks on the hub, on bolt center etc.
Verify disengaged clearance of at least 025, Maybe check this value hot, post hard session.

Grease the shaft a touch, not with synthetic grease tho.

Maybe look at crank end play.
The new cross hatch marks on the center of the disc show very uneven pressure.

Maybe you just roasted it one time and the warp is the result.
YMMV. MM
 
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