Automotive Q & A

Knowledge Database - Brakes

Question: How do brake rotors work?

Answer: The brake rotor is an iron disc connected to the tire’s hub that is used in a disc brake assembly. Disc brakes are mostly used on the front wheels of vehicles, but they have increasingly been used on rear wheels as well. Rotors work hand-in-hand with brake pads to stop your vehicle. When you step on your brake pedal, your vehicle’s brake pads are compressed against the rotor creating friction. This friction enables your vehicle to stop while also creating a tremendous amount of heat. Rotors consist of two iron discs connected by ribs. When the brakes are applied, the brake pads are pressed to both iron discs. There are many different rib designs for rotors, but they all do the same thing. They aid in dissipating the large amounts of heat created by the friction between the rotor and brake pads. These ribs allow the hot air to vent from the rotor and also direct air in to cool the rotor. It is very important for rotors to be able to dissipate the large amount of heat so they can work properly. There are also two different types of high-performance rotors: drilled and slotted rotors. Drilled rotors consist of holes drilled in specific patterns on the surface of the rotor. Even though these holes provide less of a surface area for brake pads to squeeze, they allow heat, gas, and water to pass quickly from the rotor surface. A slotted rotor has directional slots or ridges carved into the rotor surface. Again, these slots move heat, gas, and water away from the rotor surface. These two designs are beneficial for high-performance vehicles, but they have their issues. Drilled rotors are not very durable and can crack around the holes; slotted rotors can cause excessive wear to brake pads.

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