I never did say which exact disc I was using, but I'm going to assume that either way, the southbend kevlar disc I have is indeed thicker than an ACT disc.

So the springs in a pp are the real factor here then when trying to run a thicker disc.

I hope I understand when I say that the using a thicker disc in the ACT pp results in not operating where it was supposed to and is in a sense preloading the fingers. The fingers being logarithmic in nature and as throw is increasing, the proportional amount of finger movement on the pp face is getting less - it isn't linear.

If this is all the case, there seems to be immediately three viable options:

1. scrap the southbend disc and get an act sprung 6 puck
2. scrap the act pp and get a southbend pp
3. slip the living hell out of the disc to wear away until the fingers will disengage earlier and readjust everything

The one other option I see, is changing the whole leverage system of the fork, pivot, and slave to allow more travel of the TOB towards the pp with the same slave travel...the trade off being more pedal effort. This would either: increase the length between the TOB and pivot or decrease the length between the pivot and slave cylinder impact. The end result would change the ratio between the movement of the slave vs movement of the TOB. For example, going from travel ratios of 1":1" slave:TOB to 1":2" slave:TOB. All while hoping I don't ever bottom out the fork on the bell housing and that over extending the pp fingers out of their "typical" range doesn't break them off. As you said, there is a logical limit to the amount of shimming you can do before you either preload the pp or mess up the slave's throw.

I did come across your thread where your old disc and pp broke apart and you ordered the southbend disc. I wasn't able to find the end result of all that though.

It is really strange that the ACT 2600pp and southbend kevlar disc has found its home into so many DSMs and I can't find anything about it being either preloaded for a proper engagement point or the engagement point is at the floor.

I would love to hear your advise before I order a whole bunch of parts that won't necessarily fix the real problem, which I think we have established is the inability of the pp to proper disengage a thicker disc because of the physics of the pp fingers and springs within a limited space system.