I have really been looking for a system to use to replace my hydraulic clutch setup.
The idea of using an air cylinder to operate my clutch is appealing to me. I am sure an air cylinder would have enough power but the idea of being able the modulate the clutch is a sticking point. The reason I think it might be doable is there are so many air ride system being sold with a lot of R&R already completed.
The idea of being able to release the clutch with control is the problem. Any of you guys have any thoughts? Sure I might be able to set a fixed rate of engagement and that might work. I mean once you depress the clutch a switch would open the air charge to the cylinder, that part is a snap. Now when engaging the clutch one could have a set rate and you could then modulate that simply by depressing the clutch quickly if needed. Then you could have any pedal tension you want. Again I am trying to civilize the car a bit more.

How do you power it? Mount a compressor to leech off what little horepower you have, or up some sort of storage tank for holding air, which you could run out of, and then I hope your clutchless shifting is good.

Meanwile... I've been thinking of similar ideas.

I was thinking of a hydraulic setup that is pressurized by an oil pump from the cooling system that would be added to either the engine or the trans and then controlled by a pentiometer and a selenoid valve.

Oh. right. To answer your question... Pentiometer and selenoid valves. You have to set it up to detect position of the clutch pedal and reflect that. Alternately, you can have it go through a start program, where it would apply limited pressure to the clutch at low speeds, and then move the clutch quickly off/on at speed. You could probly even rid yourself of the pedal entirely if you used an rpm switch and a speed switch...

rpm<1000, speed irrelevent= clutch disengage
rpm1000-2500, speed <15mph= clutch partially engaged
rpm1000-2500, speed >15mph= clutch in on/off mode
rpm2500-8000, speed irrelevent= clutch in on/off mode (so you can still burn the tires)

Putting the rpm inputs for the different program routines on a rheostat would allow for some sort of tunability.

Approaching a gear change on the shift stick could disengage clutch when in on/off mode. Being completely in gear could engage clutch.

If you use a double acting cylinder, then you can apply a far greater amount of force against the clutch plate.

PM me if you want more, or want to start a project.