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The following are terms you should know and have been supplied by brake system experts. Clamping force: The clamping force of a caliper in pounds is the brake line pressure multiplied by the total piston area of the caliper in a fixed caliper and two times the total piston area in a floating design. To increase the clamping force it is necessary to either increase the line pressure or the piston area. Increasing the pad area or the coefficient of friction will not increase clamping force. What does this mean? That your clamping force of your caliper and brake subsystems has nothing to do with pad design or makeup nor does it have anything to do with the type of disc used. This next bit of information is really the basis for stopping the vehicle. Improving this area will get your vehicle stopping faster Coefficient of friction: A dimensionless indication of the friction qualities of one material vs. another. A coefficient of 1.0 would be equal to 1g. The higher the coefficient, the greater the friction. Typical passenger car pad coefficients are in the neighborhood of 0.3 to 0.4. Racing pads are in the 0.5 to 0.6 range. With most pads the coefficient is temperature sensitive so claims that do not specify a temperature range should be viewed with some suspicion. The optimum is to select a pad with a virtually constant but decreasing coefficient over the expected operating range of temperatures. As a result, the driver does not have to wait for the pad to heat up before it bites, and the pad fade will not be a factor so that modulation will be easy Now that we have a foundation we can see that finding the pad of the right material and heat range affects your braking efficiency. You don't want a pad race pad for the street, because you have to heat it up to its approriate heat range before it bites. Not to far of from racing tires where their operating range is higher, so getting them to stick requires more heat. The difference is here you pick a pad for your car based on driving habits, much like you would tires. If you are on the brakes non-stop and generating excessive amounts of heat then you want a pad and rotor combo designed to bite or grip at higher temps. On the street we want bite right away thus a pad with a lower operating temp, and the trade off is fade at higher temps, (excessive braking or high speed braking) or reduced bite.
OCTOBER 2017
BRAKING BASICS & BREAK IN PRACTICE