wrd1972

Three years ago I had a custom Kevlar clutch disk made locally. When I installed it I determined that the clutch would not 100% disengage with the clutch pedal fully pressed to the floor, therefore it would not go in gear. The reason for this was the total unclamped disk thickness was .348" MAX. It was just too thick. I then removed one Kevlar facing and replaced it with a slightly thinner organic facing, I remember this new disk thickness being around .330" or so but I cant be positive. This new disk worked perfectly fine with no clutch drag for three years, however this disk is now worn out.

I just purchased a brand new Spec stage 3+ disk which I intend to use with my current SLP drilled pressure plate. The unclamped disk thickness on this 3+ disk is .338" MAX.

A stock LT1 disk unclamped is .320" MAX just for reference.

I am concerned that I may run into the same problem with the clutch not 100% disengaging with this new Spec stage 3+, although it is still .010" thinner than my old first pass custom disk which was clearly too thick. This makes me wonder if Spec clutches re-surfaces all their new Valeo pressure plates with the only purpose of removing some material to avoid clutch disk drag when using thicker than OEM disks. From looking at these pics from BFrankers this might be plausible, look at the three areas just off the friction surface:
OEM pressure plate (note the three dark areas:

Spec pressure plate: (note the machined marks)


My SLP plate needs a resurfacing, I am planning on shaving .020" from which should have the same effect as making the disk thinner. This should help me avoid possible clutch drag.

Here is a photo of the Spec stage 3+ disk sandwiched between an unbolted flywheel and pressure plate. The dimension of the stage 3+ is .142" and the worn out disk is .108"


Here is a photo of the flywheel, disk and pressure plate all bolted up. The fingers are just perfectly straight level, I am thinking they should be slightly down or slightly facing the forward of the car.


My questions:
What is the "LT1 clutch disk MAX thickness spec" that can be used while avoiding clutch drag?
Does anyone have a Spec pressure plate they can look at to see if they are removing material for bigger disk?

If you have an uninstalled Spec pressure plate you can look at, please PM me.

Thanks guys.