Brake pad specifications

[MikenOH]

In reviewing various track and street brake pads specifications, there is a constant reference to the COF or coefficient of friction number, usually listed as a fraction, ranging from say .35 to .60

Would appreciate info on how to evaluate this COF figure in determining which pad is best for a particular application, specifically, what this number means relative to braking or braking effort.

Thanks for any help..

[insite]

this really tells you nothing about the pad. the dynamic coefficient of friction for brake pad material is not constant, it is a function of temperature. you would need a plot of the Cf through the useful temperature range for it to be of value. you would also need to know the surface area of the pad and average distance from the hub center to calculate effective clamping torque. you would then need to know the maximum grip force available to the tires in order to determine whether lockup is impending. to make matters MORE difficult, there are two coefficients of friction. the dynamic Cf is in play while the disk is moving, but if the disk locks up, the static Cf takes over. generally, static Cf is higher than dynamic Cf, which is why you have to let off the brake a LOT to get the wheels turning again. you can think of this like pushing a heavy box along the floor. a large force is required to get it moving (static Cf), but not as much to keep it moving (dynamic Cf).

bottom line: empirical evidence is key. talk to people who have used various pads under various conditions to get their opinions. then, try some of them to see what you like. without a brake dyno and tons of time, you'll never really be able to compare two pads without trying them in your car.