Quote:

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one bit of math missing here.

relationship of piston stroke in the M/C versus pedal ratio.

Someone here thinks less leverage is less stroke at the M/C

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Look at the chart again.

The third input requested is pedal ratio. 7 in the example.
The sixth (and last) input requested is how far you moved the pedal. 5 inches in this example.

The third output listed is "the master cylinder moved this far". .7143" in this example.

There's your stroke by pedal ratio.


You referenced FD's power booster conversion. I specifically stated that the math in these examples was for a manual brake system only and that if you used a booster you were on your own.

If you want to get into pedal effort by master cylinder size, start punching numbers.
Put in a 1" master with 100 lbs pedal effort and see what the brake torque is.
Put in a 1-1/8" master with 100 lbs pedal effort and see what the brake torque is.
Start putting higher numbers in the pedal effort until you get back to the same brake torque.

Going from the example's 15/16" master cylinder to a 1-1/8" master cylinder shows that the pedal effort increases from 100 lbs to 144 lbs to get the same brake torque. A 44% increase in pedal effort is not going to make for a happy driver.

Go back and play with the numbers and see what the spreadsheet will do for you. It's kinda fun.