Ok ,since my last post on this topic I havent spent time at all on the car since last November. I'm back at it now and determined I was only getting partial clutch disc release with 0.480-.490" (crude measurement) of movement from my McLeod HTOB. This is with the 3/4" Master and 1.1" of stroke. I think I need no more than 0.100" of ADDITIONAL pressure plate movement to get full release of the disc (I can shift ok now but rear wheels still turn with clutch pedal all the way in, indicating disc is still dragging. The Mcleod states total HTOB movement from full compressed to full extention is 0.890". So with my 0.160" initial gap to PP fingers with piston fully compressed + the 0.480" of current piston movement, I have (0.160+0.480)- 0.890 or 0.250" left until I'm at the end of HTOB piston travel.
ANSWER: I confirmed today it takes 0.575" pressure plate finger compression to COMPLETELY disengage my clutch disc. Clutch pedal to the firewall (full travel) and input shaft fianally stops turning @ 0.575" of HTOB movement !!!!!. But this comes with a too large of a pedal tavel so the 13/16" bore M/C will remedy that situation.
So yesterday I ordered the next size up Master Cyl which is the 13/16" bore which I hope, with the little extra fluid volume will find the "sweet spot" for clutch pedal stoke, and of course, the complete release of the clutch disc. I'll report back after its installed. Pedal force should remain resonable as well.
I have a stupid question for those with these concentric HTOB's. Where do I find the published piston area for the McLeod's HTOB? Do i have to measure it myself ? I have a few extra's left from my intial set-up I can measure.
UPDATE: I could not find any published piston area sizes, So I measured a spare concentric piston for the bolt-on style Mcleod HTOB bearing used on the Tremec TKO. Its a donut shape and I came up with a slave piston surface area of exactly 2.0 square inches.
I also found this article that helps explain how to calculate your clutch set up requirements. Happy reading.
Clutch Calculations