I think you are looking for film strength. Most petroleum base lubricants will be force from between 2 surfaces at about 6,000 psi. Some greases are higher, but it that pressure you have metal to metal contact starting to happen, at about 10,000 psi most petroleum based materials are gone.

It sounds like he wants to know how far the plates must move apart to stop dragging, not how close they must be for full torque transmission?
(sorry, I don't know)

Jay Maechtlen

Hi there
Yes thats it ....how far do the plate have to be apart , sorry a little difficult to phase things,

I have a couple of formulas , but I am not sure if I am using them correctly ( petrovs i think )
F= mu x a x u/h  where u is speed and h is height..
Hope that helps

there are other things to consider. when a clutch sticks, it might well be the additives in the oil employed that cause the problem. this is frequently seen in motorcycle transmissions where a standard gasoline engine oil occasionally gives rise to problems, where a dedicated motorcyle engine oil does not.

ATF's are designed for particular combinations of platematerial to give the required frictional characteristics. if your design differs considerably, it might well cause problems. my advise would be to use another thin oil, oreferably without additives and see whether that makes a difference.