Diaphragm Pressure Plates- Ratios- A Math question

[kitcarbp]

I am hoping someone here has some info. For an 11.00" diaphragm type of pressure plate, what is the Ratio of the "Finger compression" distance to the "Pressure Plate" (friction surface) movement.

I found an article that referenced a ratio 6.6:1 for 11.00" diaphragm pressure plates but how is this ratio derived? Do all 11" diaphragms have this ratio, plus a small tolerance ?
Mine is exactly an 11.00" Mcleod 380650 diaphragm type PP.

As an example that ratio would give you 0.100 inches of pressure plate release for 0.660 inches of PP finger (spring) compression (throwout bearing face travel)

The Diaphragm Ratio data I cant find published by the clutch manufacturers.

Sooooo.... to follow-up here, I found a great technical paper written by LUK clutches that explains the level arm ratios in a simple diagram. I will try to post if I can shrink the file size. But in summary an 11 inch PP will always be real near to 6.6: 1. The manufacturers have the exact figures for these ratios and I cant find them published.

Thanks