When I started reading "the math", I was certain the pad/rotor friction coefficient would be "a value" as "a constant" of sorts. Which is fine for the calculations used.

On the edge of brake pad material is that pad's "birth certificate". Listing a code for the manufacturer, batch/date manufactured and/or other ID, AND the pad's coefficients when "cold" and "hot". Letters from "C" to "F", I believe. The letter code is two letters, first being "cold" and the second being "hot".

Question might be just how much difference there might be in these coefficient levels?

When vehicles started to be downsized in the 1980s, brake components got smaller, too, for the lighter cars. Pad dimensions were also decreased as metallic pad compositions became more common . . . less pad, more stopping power (brake torque). On many current "supercars", the rotors have grown to larger diameters and brake pads seem to have (again) become smaller in surface area.

Another "given" will be a constant surface finish of the rotor itself. A shiny smooth used surface might have less "bite" than a freshly cut and patterned or new (with factory in-broken-in contact surface) rotor.

The key curiosity is the difference between the pad co-efficient letters?

Thanks for all of the great information!
CBODY67