[RodgerH]

OK, I looked at some notes and a sketch I made when I was installing the flywheel/clutch.

I have a McLeod aluminum FE flywheel (p/n 563210). The outer portion (where the pressure plate attachment holes are located) is 0.956" thick. The pressure plate attachment holes are counterbored (for the shoulder on the bolt) to a depth of 0.290". The remainder of the hole is tapped 5/16-18 through the flywheel (not a blind hole). The threaded portion is 0.666" deep.

The ARP fasteners (p/n 250-2201) have an underhead length of 0.750", with a shoulder length of 0.250" and a thread length of 0.500".

The Centerforce pressure plate cover is 0.150" thick where the mounting holes are drilled.

0.250" (bolt shoulder length) minus 0.150" (pressure plate cover thickness) equals 0.100" of bolt shoulder extending into the flywheel hole counterbore. (That didn't seem like very much, considering the counterbore is 0.290" deep.)

Do the math and I had 0.310" of the end of the bolt threaded into the flywheel (less than 6 threads into the 0.666" deep hole).

I didn't think that was enough thread into the aluminum flywheel, thus the reason I went with 1-1/4" long grade 8 bolts. With an AN washer, the bolts extended about 1/16" through the back of the flywheel.

After this discussion started yesterday, I called McLeod Tech Support and explained this to him. He didn't seem too concerned and said the 5/16" (0.310" true measurement) of thread engagement was equal to the diameter of the fastener and was sufficient.

If this were a steel flywheel...maybe. Because it is aluminum...I'm less confident. My next step will be a call to ARP when they open this morning to get their take on this. I'll post what they tell me.

Rodger