heavy clutch question.....

[BruceA]

The 'springy thing' that may be between the puck friction surface and plate are called the 'Marcel Spring', generally used on street driven cars for smooth engagement.
I cannot understand why a shaft change has done this. You must have something binding. I have gone from a 2-peice to 1-peice shaft of my own design for my UN1-13 box and had no problem with the cluch. My clutch is very light, its an 11" plate. I sat down and designed the whole thing from scratch to make sure my pedal pressure was easy enough. I even made the slave cylinder from a peice of tube with brake wheel cylinder cups for seals.
It could be that the plate is being 'stuck' on the end of the splines as Jac mentions. There is not that much left even on the standard shaft. When I had my shaft machined I made sure I got an extra 10mm or so of spline for this very reason. Some careful measuring may be in need here.

 

[Malcolm]

Well I took the leverage option and went from 4:1 on the pedal to roughly 5:1. This has greatly reduced pedal pressure but clearly would lengthen pedal travel. BUT because I recently put in a Gurney Bubble I can now sit better in the car and so was able to move the pedal 1/2 inch towards me. This kept the bite point inside the cockpit.

I acheived this ratio alteration by making a billet ali bracket to fit to the plunger that mounts to the pedal and drives the master cylinder. I made it offset so that the plunger is still horizontal but the actual pivot point is 1/2 inch higher up the pedal. Drilled a higher hole in the pedal to suit and hey presto, 40 mins work and a lighter pedal pressure with option to move it back to 4:1 with a 5 minute operation which can now be done trackside.

Thanks for all the input, although I am still intrigued to try the bigger pipe option some time. Someone has told me they got an improvement when they went from brake pipe sized pipe (I think 1/8) to 1/4 inch pipe so the theory has some validity but whether it still holds true from 1/4 to 3/8 pipe is not yet tested.

 

[Jac Mac]

Malcolm,

There would be some merit in going from 1/8" bore to 1/4" as most Fords ( UK ) have a 1/4" pipe from M/cyl to slave cyl. However this should be all that is reqd to remove any potential flow restriction. Most of the Aussie Fords in the 70's had 1/8" bore lines ,even the GTHO Falcon twin plate setup, with no fluid related problems.

Jac Mac