Every time you activate the brakes of your BMW, the high amount of friction used to stop the vehicle is turned into great amounts of heat energy. In order for the brakes to operate efficiently, this heat must be removed from the system, and that is the job of the BMW brake disc. This part is made of metal to transfer the heat from the braking surface to where the heat can be removed by the open air. To increase the amount of surface area and, thus, the cooling efficiency, the BMW brake disc uses a series of chambers, called slots, that begin on the outside edge of the disc, and run towards the center. As the BMW brake disc turns, air is drawn into these chambers, and it absorbs the heat from the braking surface. To further increase the surface area for cooling, high-end versions of the BMW brake disc use methods such as cross-drilling and special surface groves. After many years, wear and corrosion will affect the surface of the unit, reducing the life of the brake pads, and rust or other debris may collect in the slots, reducing the cooling ability. Sometimes this type of damage to the BMW brake disc can be corrected by machining the surface of the disc and cleaning the slots thoroughly. When it becomes necessary to replace the BMW brake disc, however, you will find the correct version for most vehicles in our large online catalog, for a great price. Our version meets or exceeds all of the specifications of the original part, and it has a full warranty from the manufacturer. Ordering the new BMW brake disc is as simple as visiting our secure web site at any time, or calling one of our friendly associates, toll-free.