Hydraulic Clutch

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10-05-2010, 04:29 PM
rspears

Hydraulic Clutch

I have a Wilwood compact clutch master, 0.75" cylinder and my pedal travel yields only 7/8" master cylinder stroke. My slave is a 7/8" cylinder (0.875") so the travel at the clutch fork is between 5/8" and 11/16" and is not enough to disengage the clutch. This Wilwood master is one used by many stick applications, and a 7/8" slave is not unusual. Anyone know how much travel is needed at the clutch fork with a Mustang fork, passenger side pivot? I am looking at possibly replacing my 3/4" master with a 1.25" Wilwood unit, giving me about 1.125" of clutch fork travel. The other option is replacing both slave and master, but I am trying to salvage what I can.
10-06-2010, 05:07 AM
bobscogin

Why not just move the slave cylinder push rod closer to the fork's fulcrum? That will get you more travel.

Bob
10-06-2010, 05:26 AM
rspears

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Quote:

Originally Posted by bobscogin

Why not just move the slave cylinder push rod closer to the fork's fulcrum? That will get you more travel.

Bob

The fork is a passenger side pivot, pushed from rear to front on the drivers side to actuate, and the connection to the slave pushrod is right at the bellhousing opening now. To get the travel (that I think is needed) that point would have to move several inches, putting the slave well inside the bellhousing. Good idea, but not going to work for this one. Anyone know of a pusher slave like CNC's below that has a 1/2" or 5/8" bore??
10-06-2010, 06:53 AM
jerry clayton

now maybe you are starting to realize why ford used a cable on that setup?
10-06-2010, 12:35 PM
rspears

Quote:

Originally Posted by jerry clayton

now maybe you are starting to realize why ford used a cable on that setup?

:LOL:Yep! But I got it figured out a bit ago, and it may help someone else later. The key to my problem is that the clutch MC had only 7/8" stroke compared to full stroke of 1.4" - shy of full travel by 0.525" and the volume of fluid available to the slave was is not enough. If the pedal assembly pivot were forward an inch or so there would be more pedal travel, and thus more MC stroke. The solution, rather than cutting the frame apart, is to extend the pedal length at the top, following the existing arc, to add enough more pedal travel to yield full stroke on the MC which will give me greater than 1" travel at the clutch fork. Problem solved, or will be soon....
10-06-2010, 12:57 PM
jerry clayton

you do realize that to gain that 1/2 of piston travel that you will need about 3 or 4 inches more pedal travel?????

You might want to do a little more thinking on this as a human cannot move his foot at the speed necessary to use that much pedal

The problem seems to be in your pedal assy---thats what you need to change--not the length of the arc, the diameter of the cylinder, etc
10-07-2010, 04:38 AM
rspears

Quote:

Originally Posted by jerry clayton

you do realize that to gain that 1/2 of piston travel that you will need about 3 or 4 inches more pedal travel?????

You might want to do a little more thinking on this as a human cannot move his foot at the speed necessary to use that much pedal

The problem seems to be in your pedal assy---thats what you need to change--not the length of the arc, the diameter of the cylinder, etc

Jerry,
I really appreciate your comment. Last night I measured a bunch, made a pattern of the pedal arc and determined the added 2.5" of travel needed at the top. Looking at it, the way the pedal assembly (which came as an assembled master cylinder bracket/pedal assembly from Pete & Jake's) is mounted there's three full inches of pedal arm (the arched part) outside the body, so adding 2.5" is not a bad approach - it is still shorter than Henry designed for foot travel, and I know another guy that used the approach on his car, too and it works just fine. I thought that I could notch the floor, but it hits too far up on the pedal, so extending the arc is the only thing that works. Thanks for questioning my idea - it is good to think through it again!!