General brake specifications for cars include foot-pounds for brake caliper bolts and the size in inches for the master cylinder bore, disk thickness and drum diameters. Details vary by manufacturer, year, model and wheel location. Critical dimensions appear stamped on the brake surface.Continue Reading
Bracket and mounting bolt torques are standard caliper bolt measurements. Bracket bolts require torques over 100 foot-pounds while mounting bolts need torques under 100 foot-pounds.
The master cylinder bore controls the pressure required to brake. Dimensions range from 3/4 inch to 1 1/18 inches and relate directly to the brake caliper configuration.
Disk thickness includes the maximum size of a newly purchased brake pad, its smallest dimension appropriate for resurfacing and the minimum thickness marking the need for its replacement. For many domestic cars, the margin between maximum and minimum thickness is 0.15 inches. Runout also relates to disk thickness and is the amount of the rotor's lateral movement during rotation. Outside the recommended variations of 0.002 to 0.006 inches, runout demands increased pedal action to compensate for any slippage.
Drum measurements also include the original and replacement thickness values. A margin of 0.090 inches is typical, with a resurfacing margin of 0.060 inches. Drums outside the recommended range lose the ability to dissipate heat, leading to warping and brake failure.Learn more about Brakes