calculating brake force???

[David Pozzi]

We put the Baer/pbr type brakes on Mary's second gen. I tried to go manual with it and tried master cyls down to 13/16" bore, I used early 70's Ford master cyls. With the 13/16" I could barely lock the front wheels if I really stood on the pedal, mary could not press that hard. There was no way we would want to open track the car and have to work the brake pedal that hard over 1/2 hour at a time.



I went to the stock type booster and a 15/16" master cyl and it was about perfect except the Baer provided pads would lock the rears up on the first hard application when cold. Once slightly warm, they worked fine but wore out the first track day. Anyway, a manual 3/4" bore might be about right or a 5/8". I just ran out of time to experiment further and went back to power boosted.

I believe any advantage of a 6 piston is in a slightly stiffer caliper due to the smaller bores leaving more "meat".

On pad size, formulas I've seen say to not consider pad surface area when calculating brake torque. It's piston load in pounds, X pad coefficient, X rotor radius, ÷ by tire radius.

This assumes the pads are correct for the application.
A larger pad will have a softer compound because the unit pressures are lower.

Older large piston caliper designs use much lower line pressures and probably have less flex of brake hoses (hysteresis).