Work has been continuing on the pedal box. I had a setback with the clutch pedal as the throw designed into the pedal for the Wilwood "Shorty" master cylinders proved to be inadequate for the Girling-style master cylinder supplied with the hydraulic clutch kit.
There was a suggestion to move the rod mounting location to the rear of the pedal, behind the pedal pivot point. That would work, but the rod to the master cylinder, only 5/16" diameter, would be too long, and possible subject to bending. I needed to take another approach.
I found a nice little free kinematic program on the Internet called "Linkage." It works on windows and looked to have everything I needed for my design. I downloaded it and spent a couple of days learning it, then started on new designs.
It took 9 different iterations of my basic idea to get what I wanted. For me it's a "good" solution in that: 1) I understand it; 2) it satisfies the basic functional requirements; and 3) I can actually fabricate the parts necessary without hiring a machine shop. Here's what the logic looks like graphically:
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Build log Example.jpg
It does 4 things. It makes the travel of the master cylinder rod pretty close to linear, varying just slightly (< 1/4") over it's complete movement. I now have slightly more than 1.65" of travel and I need 1.4", so I have a slight surplus, which I will limit with a stop. I can change the relationship of travel to pedal movement (should I ever need it) by changing to a different link shown as DEJ in the graphic. And, last, it keeps everything in front of the pedal which will be nicer from a safety and aesthetic point of view.
Here's a detail of part of the realized design shown in the kinematic graphic:
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Alternate Clutch Detail.jpg
I've made several of the parts already:
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Rather than use very thick steel, I welded some 16 gauge spacers onto the clevis attachment flange to take up slop. It ended up working quite well and does not require a washers, etc.
I want to improve the brake pedal situation too, but for different reasons. It needs some stops and return springs. However, developing a new kinematic solution for the clutch made it possible to preserve all the other work I've done thus far.
Cheers,