Can someone tell me if the external return spring, seen in some photos between the clutch actuation arm and the bellhousing near the slave cylinder, is necessary if the transaxle is the type with two fairly robust return spring coils on the center of the actuation arm shaft, on each side of the throwout bearing?
ZF clutch return spring
- Thread starter toy264
- Start date
Use one or the other, but not both as that would introduce redudantcy.
True. Take a look at the image below from the ZF factory parts book:
The coil springs that are located on the clutch withdrawal shaft (#1004 and #1008) were no longer installed by ZF starting around 1972, as they were apparently considered redundant and unnecessary. When Lloyd Butfoy receives an earlier gearbox for overhaul that still has those springs, they are removed and tossed in the trash.
Various Pantera vendors sell different external springs that go between the external clutch arm (#1012) and the mounting bracket for the slave cylinder. Some of them are far too stiff and result in excessive pedal pressure. The spring needs to be powerful, but only powerful enough to ensure that the fingers on the clutch withdrawal fork (#1007) are not riding on the surface of the throwout bearing.
Also, FWIW, McLeod (and perhaps others) now sell 'constant run' bearings which are specifically engineered to allow constant pressure from the fork. I would presume that keeping the fork off of one of those bearings would be beneficial, but unlike a conventional bearing, it's no longer critical.
Thanks guys- but I'm obviously missing something. I thought the two internal springs had the same action as an external one--to release the throwout bearing from the clutch fingers, allowing the plate(s) to engage. Aren't two internal springs and the spring-back of the clutch itself redundancy enough to do that?
