Big Brake Kit Info - Performance - Super Street Magazine

To go further it is necessary to understand some of the physics involved, and that requires some definitions.

To go further it is necessary to understand some of the physics involved, and that require

The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with discs used for race cars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1,000 degrees F, the ratios on a racing two-piece annular disc design are 10-percent conductive, 45-percent convective and 45-percent radiation. Similarly on a high performance street one-piece design, the ratios are 25-percent conductive, 25-percent convective and 50-percent radiation.

Braking performance is about more than just brakes. In order for even the best braking systems to function effectively, tires, suspension and driving techniques must be optimized. For maximum brake potential, vehicles benefit from proper corner weight balance, a lower CG, a longer wheelbase, more rear weight bias and increased aerodynamic down force at the rear.

To go further it is necessary to understand some of the physics involved, and that requires some definitions.

1) Mechanical pedal ratio: Because no one can push directly on the brake master cylinder(s) hard enough to stop the car, the brake pedal is designed to multiply the driver's effort. The mechanical pedal ratio is the distance from the pedal pivot point to the effective center of the footpad divided by the distance from the pivot point to the master cylinder push rod. Typical ratios range from 4:1 to 9:1. The larger the ratio, the greater the force multiplication (and the longer the pedal travel).

2) Brake line pressure: Brake line pressure is the hydraulic force that actuates the braking system when the pedal is pushed. Measured in English units as pounds per square inch (psi), it's the force applied to the brake pedal in pounds multiplied by the pedal ratio divided by the area of the master cylinder in square inches. For the same amount of force, the smaller the master cylinder, the greater the brake line pressure. Typical brake line pressures during a stop range from less than 800 psi under "normal" conditions, to as much as 2,000 psi in a maximum effort.

3) Clamping force: The clamping force of a caliper is the force exerted on the disc by the caliper pistons. Measured in pounds clamping force, it's the product of brake line pressure, in psi, multiplied by the total piston area of the caliper in square inches. This is true whether the caliper is of fixed or floating design. Increasing the pad area will not increase the clamping force.

4) Braking torque: When we're talking about results in the braking department we are actually talking about braking torque; not line pressure, not clamping force and certainly not fluid displacement or fluid displacement ratio. Braking torque in pounds-feet on a single wheel is the effective disc radius in inches times clamping force times the coefficient of friction of the pad against the disc all divided by 12. The maximum braking torque on a single front wheel normally exceeds the entire torque output of a typical engine.