- Wheels & Tires
Brake rotors are more than just a pretty face. While they are available with a variety of surface finishes such as cross drilled holes, slots, a combination of holes and slots, and other proprietary designs, brake rotors are more than a fashion statement or mere eye candy. Brake rotors serve an important role: managing heat, friction and heat dissipation duties while also working to efficiently shave speed under every possible driving condition.
The process of stopping generates heat that is then transferred to the rotors. The rotors must be able to draw heat away from the pads while also managing the dissipation of heat whenever possible. Rotors are often made from iron due to its heat transfer and storage qualities, durability and strength. Rotor heat management comes in the form of venting, along with surface treatments. Aftermarket brake rotors, like those offered by STILLEN, AP Racing and DBA, can feature a variety of benefits thanks to engineering innovations, such as enhanced vane designs (in the case of vented rotors) for improved rotor cooling as well as a variety of surface treatments to enhance the bite between the brake pads and the rotors.
With exception of select high-performance and exotic applications, the majority of stock rotors that equip road going vehicles have no surface finish. This is often sufficient for street driving. When it comes to performance situations, these brake rotors leave much to be desired. In order to improve braking performance, brake manufacturers and the aftermarket sought solutions to the friction problem.
An old and popular solution, cross-drilling the rotor surface, has served in performance applications for many years. Contrary to popular belief, the holes in the surface do more than simply facilitate cooling and out gassing, they offer an edge that bites into the pads to generate friction for stopping. (Counter point: It is not unheard of for cracks to develop between the holes of a cross-drilled rotor after repeated heating and cooling cycles over time.
Another rotor surface treatment is to cut lines or slots. The slots help to optimize the friction surface area while biting into the pad surface for friction generation. It also helps to release the gasses that build up between the friction material of the pad and the rotor surface. Venting these gasses ensures that the pads maintain contact with the rotor surface for optimal friction generation. However, this rotor type could cause accelerated wear on the friction material, shortening the typical service life of the pads.
Some manufacturers combine the merits of these finishes, offering a cross drilled and slotted rotor to consumers.
Another available finish is proprietary to a given manufacturer. For example, the STILLEN Chicane Series S-groove rotor. This rotor finish optimizes friction surface area while providing increased groove surfaces for improved pad bite and out gassing.