In the channel of the U-shaped device known as a brake caliper, you will find the metal disc that is your Audi S4 brake rotor. Along with calipers, brake pads, brake hose and lines, your S4 brake rotor works to stop your car safely when you need it to stop. The Audi S4 brake rotor works most closely with your brake pads.

Between them, these two parts generate massive amounts of friction. This occurs the moment you step on your brake pedal: the hydraulic fluid conveys force to the calipers, which clamp the brake pads against the S4 brake rotor on either side.

Though your Audi S4 brake rotor is a tough piece of equipment, it is subject to wear over time. The most common cause of damage to your S4 brake rotor is due to your brake pads. One way in which your Audi S4 brake rotor can be damaged is through driving and braking when your pads are worn to less than a quarter of an inch thick. You should change your brake pads when the lining is between one quarter and one eighth inch thick; any less than that, and your S4 brake rotors will be scraping against the metal backing plate. Another way your brake pads can damage your Audi S4 brake rotors depends on the type of brake pad you have installed. There are basically two materials brake pad linings are made with: metallic substances like copper and bronze, or organic substances and fillers. If you have brake pads with metallic lining installed, your S4 brake rotors will wear faster than if you were using organic brake pads.