Clutch Pressure Plate Bolts

[A26B]

Maybe I shouldn't be concerned about it, since I've not heard of any catostrophic failures, just loose bolts about to cause problems.

Changing out flywheels from the nodular iron, dual mass to aluminum flywheels, Fidanza in my case, is where problem manifests, at least in my mind and a few others. The problem is...using stock bolts in an aluminum flywheel and the lack of sufficient thread length engagement.

Now, there is a new set of circumstances with a potential problem also pertaining to pressure plate bolts. The replacement pressure plate being sold today is the same height (thickness) as the LT1, which is thinner than the original LT5 part. Stock bolts are too long and are being replaced with "off the shelf" bolts of varying grades. This concerns me.

The following photos show the difference between "off the shelf" bolts and the OEM design. Its necessary to add a dimension to thinking about the job bolts do when it comes to clutchs. Mostly, bolts are stressed axially. Clutch bolts are stressed axially to, but also in shear. The OEM bolt is designed to cope with shear, "off the shelf" bolts are not. The difference is shown in the photos. OEM bolts have more beef where shear stress occurs and no stress risers. Shear stress is imparted to the counterbore in the flywheel as opposed to "open" threads in the counterbore area and pressure plate bolt hole.

Ron Woods offers the ideal replacement bolt for use with the aluminum flywheel. I don't know if he has made one for the thinner, replacement pressure plate or not. It may not be necessary. The stock LT1 bolts may be the ticket if used on the irn, dual mass flywheel. If used on an aluminum flywheel, I hope Ron makes a new bolt for that application.

I'm old school and have seen the aftermath of flywheel & clutch explosions at high RPM. It ain't pretty. Such a small item, often overlooked but very important. Let's discuss & see if the result is worthy of a "sticky" recommendation.

Jerry