QM twin disc failures on the hubs. I should get a prize for worst failure. Pics.
 

This is the now older-hardened hub style. I had tried to get more life out of the disks by having the inner short hub machined down .050". That is not enough material to get into the splines of the hub, just the taper from the splines to the face. This was the second set of discs. I now have the "gear-drive" discs in my 6-leg cover version of the clutch.

Either I am much harder on my car than other people who have done it, or heat from machining annealed the hub, or it was just a terrible idea. This was after ~5000 miles of use. Two days of road course time, about 50 launches/drag passes and a round trip drive from Ft Campell, KY to Minneapolis, MN.

Car makes just over 500whp and 450ft-lb. Car was DD'd until the clutch failure.

Disc with the tall hub, front.
Splines beatup a bit
http://i63.photobucket.com/albums/h1...mage/018-1.jpg

Disc with tall hub, back side.
That broken center section is only held in place by the face of the rivets, and only doesn't free spin because it binds up on itself after about 15° of play
http://i63.photobucket.com/albums/h1...mage/017-1.jpg

Disc with short hub, front.
See that nice pretty round hole?
http://i63.photobucket.com/albums/h1...mage/019-1.jpg

Disc with short hub, close up.
lolwtf.
http://i63.photobucket.com/albums/h1...mage/020-1.jpg

Input shaft from the trans.
The 3 states of splines. Unabused-beatup-nearly missing.
http://i63.photobucket.com/albums/h144/Bramage/021.jpg

Closeup
http://i63.photobucket.com/albums/h144/Bramage/022.jpg

Very nice!

damn. Do you drag race on slicks?

Nope, street tires are all I got.

Time for a billet input shaft?

How did the car feel after the failure? Symptoms?

Damn, nice work.

The tall hub disc probably failed first, which left all the load on the single disc which then stripped the splines off.

The wear on the disc that didn't strip the splines is very concerning though.

You say you have the "gear drive" hub with the older 6 leg cover?

exedy twin

Yes, I called QM and asked. You can run the gear drive hub discs on the 6 leg cover. Same PP, flywheel, intermediate disc as the old style hubs. The gear drive discs are ~$500 vs ~$250 for the "hardened" hub ones.

266663RY is the Gear-Drive discs part number from QM.

Aside from the terrible noise, I had no idea anything happened. I had driven from KY->MN beat on my car for 2 weeks(1/4 passes, road course, frumrolls) and drove home to KY. It didn't make a single strange noise until I was coming off of I24 onto US41 towards FT. Campbell. It made a terrible noise leaving the gate coming on post then it sat parked until last week. It didn't feel weird on that engagement or anything.

FWIW, after about 100 miles of driving home/around from RS Motors who did the work replacing stuff, I like how the new discs feel over either set of the "standard" discs I had. That drive includes rush hour traffic all the way across Minneapolis on the way home.

Damn!!!!!!

WOW!!!!! The input shaft from the trans part is a real bummer there! It sucks having one thing break and take out something else with it

+1

ouch!