[A26B]

Originally Posted by rhipsher

........and 6 3/8-16 x 2.25L grade 8 preasure bolts. The thread engagement is much deeper than the stock bolts with the same shear engagement as the stock ones. They just have 1/2 inch more thread length........

I'm not sure what you are referring to as "shear engagement." Please provide a bit more info about this.

The following comments pertain only to the OEM pressure plate, NOT the new, "thinner" replacements.

You can see that the STD bolt will not work. The threads are long enough to provide the additional engagement in aluminum, the shank of the bolt is too short @ 1.32". The shank is not long enough to extend below the pressure plate, into the flywheel counterbore. It leaves threads exposed above the counterbore and less resistance to shear forces. There are other deficiencies with the STD bolt. (1) The head does not have a flange that will prevent digging into the alum pressure plate, (2) the diameter of the shank is 0.004" smaller and (3) the shank is not machined square at the transition to threads. Such a transition would make it difficult to obtain sufficient shank penetration into the counterbore and not bind on the thread transition before the bolt clamps the pressure plate to the flywheel.

This is waaay long winded but there is simply no good "off the shelf" substitute for the OEM design. It was engineered with a purpose, from the flange, to the shank dia, length & thread juncture.

The OEM bolt is marked as a Grade 5. Grade 8 has a higher tensile strength. Grade 5 will bend or stretch more before it breaks, than a Grade 8 will. Grade 8 can be torqued higher, providing more clamping force, but it is less resistant to breaking from flexing & stress risers. Grade 8 offers some compensation to the "off the shelf" design issues, but doesn't solve them.

I'm not trying to scare you, just want to make sure this subject reaches it's proper resolution for everyones safety.

See you at Thunder II!!