Over the last few days I’ve removed the engine & transaxle from the chassis to install a clutch & pressure plate. I’ve learned a few things in the process— the hole in the rear of my Lunati crankshaft is the early Chevy 1.709” diameter. The KEP adapter pilot bearing is a caged needle bearing pressed into an aluminum cylinder; unfortunately I found that it was slightly oversized and it‘s now stuck in the crank, protruding about 1/8” and it will not go in any further. I’ll drill & tap two holes in the aluminum and pull it out and toss it into the trash. I have found a ball bearing that might fit without any aluminum sleeve so it is now on order.
Porsche did not distinguish themselves with the G50 clutch design. The original rubber center clutch disk had a habit of disintegrating so it was retrofitted by customers with a spring-centered disk made by Sachs. The clutch release lever arm also has problems—Porsche used caged needle bearings in the pivot and, after some time, those bearings disintegrated. A new bearing “upgrade” was offered but it was necessary to machine the tranny case to fit. The “upgrade” was later upgraded and then the cutting tool for the first upgrade was discontinued. Now the latest version uses plastic bushings in the lever arm and caged needle bearings on the cross shaft. This shaft is not allowed to rotate, so why they use needle bearings to support a shaft that doesn’t rotate is beyond me.
The choice of needle bearings for a clutch release arm is particularly bone-headed. A needle, roller, or ball bearing is not suited for an application where it simply rocks back and forth a few degrees; eventually it forms a channel in the grease and begins to fret the bearing and race. Eventually the bearing fails—add some clutch dust and it hastens to failure. Porsche trumpets their engineering expertise but I have to wonder how they could make such basic errors. I’m going to insert two Fabroid bushings for my cross-shaft. Those won’t fail.
Another lesson—the earlier G50 throwout bearing ID was 34mm and it slid forward & back on a 34mm OD guide tube. For some unexplained reason, Porsche changed to a 32mm throwout bearing and guide tube. Fortunately, the KEP kit had the right TO bearing for my G50 (34mm). I bought the KEP adapter kit some time ago so it would be a good idea to measure the guide tube in your G50 before buying a TO bearing. A new guide tube is about $80 so it isn’t a tragedy if your TO bearing isn’t the right size.
I have thought about ordering a KEP metallic clutch disk but the Sachs disk in a KEP Stage II pressure plate looks like it will handle the torque of this engine.
It’s an adventure!
Regards, Neil Tucson, AZ
