Clutch Master Slave Cylinder Question

[patrickt]

We have a lot of clutch experts on here, blykins being one of them, but it doesn't look like any of them are going to reply to you. That may be because there is not one single answer to your question. If you are asking, "how far do the fingers of the pressure plate need to be pushed in before the driven disk will spin freely" then the answer will be different for different pressure plates (and for different thicknesses of the driven disk on those plates). My PP opens up with just about .5" of finger travel. In our local club, we have seen other Cobra PPs that need a good .7" of finger travel. We learn this little lesson by swapping in the latter for the former and then the clutch won't disengage after the swap like it did before the swap. With that in mind, your TOB is going to have to move that needed disengagement amount, plus any air gap. So then how far does your fork have to move? It will depend on the fulcrum point of the fork on your bell housing (just like your rocker arm ratio on your valve train). Now to answer your question, how far does your slave have to push the end of the fork so everything works right? The answer is "far enough to do all of that, and pick up any slack in the process." And, in my experience, the only way you're going to be sure is to have it up on a lift with someone pressing the clutch pedal while you stand under the bell housing watching it all work and spinning a tire to make sure the disk is spinning freely when the clutch pedal is all the way in. You just can't do it with a pencil, paper, and ruler.