Replacing original factory clutch Options

[JeffBowlsby]

Replacing an original factory clutch dated 7/73, as it had started shuddering at launch and making weird noises. A "while I was in there" job. ~50Kmi car. This transaxle had never been previously removed from the car.

See the original disk compared to the new replacement disk.

The orig clutch disk has some kind of rubber 'spring/cushion chunks ' inside, mostly deteriorated and most of the rubber chunks are missing now. A piece of a remaining chunk can be seen in the round hole viewport at the clutch disk center.

Original flywheel had been factory balanced and the bolts were not clearanced. No visible wear on flywheel bolt heads.

Clutch disk is made of two thinner friction disks separated by a center metal plate carrier plate with flat springs presumably to somewhat cushion the shift change process. I noticed that the friction disk on the pressure plate side had more wear (was thinner) than the friction disk on the flywheel side.

[Ninja]

Does anyone know when Porsche moved to the damper springs?

Those rubber dampers suck bigtime, especially when the rubber is 50 years old!

The un-even wear (more to the pp side) is normal on everything.

The inner plate between the friction sections is critical.

A "race" clutch will often have a solid flat plate. A street clutch will have a "bent" wavy plate.
Either style can have the damper assembly as well. Most competition clutches do not.


Most street clutches have both the obvious spring or rubber dampers and the wavy plate between the friction surfaces. You should be able to slightly squeeze the two friction surfaces together. This style of friction mounting seriously reduces clutch grabbiness and judder.

I believe this style of friction mounting is classified as a "marchel" plate but I may have the terminology wrong.

For streetcar applications it is a requirement in my book. Often times you can see the waviness in the plate between the friction surfaces.

Of note: most modern clutch discs have no damper section and are solid plates but the flywheel is "dual mass". Many enthusiasts replace the heavy dual mass flywheels with lighter solids and then suffer the results. Massive judder, grabbiness, and often loud rattling from the transmission at idle are the normal results.

Want smoothness?
Have both a spring damper and the marcel plate in your clutch disc if you are not using a dual mass flywheel.

I believe Porsche changed over to dual mass set ups around the time they went water cooled. My 99 Boxster has a DM flywheel.

I hated DM flywheels at first, but I've now seen so much BS changing DM to solids that I have changed my opinions regarding them.

When I convert to the LGX V6/Boxster 6 speed combo I will try to use the stock GM DM flywheel...