[Tommy]

I removed and disassembled my leaky Tilton clutch master cylinder an hour ago and discovered lots of black sludge in the fluid. I subsequently discovered the inside bore of the master cylinder smooth except for score lines for the first inch or so on the top half of the cylinder. I suspect the clutch rod is not pushing parallel to the master cylinder bore when I depress the clutch, and that is causing the piston to rub the top of the cylinder. I believe the black sludge is finely ground aluminum from the scored cylinder. What do you guys think?

P.S.
I've seen several posts warning about the need for a stop on the clutch pedal to avoid over extending the slave cylinder. How do I determine where to put the stop to preclude this problem?