Most modern cars utilize disc brakes, which offer much more reliable stopping power than older drum brakes. The disc in a disc brake system also goes by the name of the rotor. This component attaches to the wheel of the car. When you press your brake pedal, the caliper holding the brake pad closes around the rotor, slowing its rotation.
This method of stopping causes the brake pad to wear down over time. It can also lead to damage and other problems for the rotors themselves. If you would like to learn more about the kinds of brake rotor problems mechanics often see, keep reading. This article will provide a useful introduction to three common brake rotor issues.
Most manufacturers make brake rotors out of cast iron and other similarly strong yet corrosion-prone metals. Many car owners become worried when a casual inspection reveals that their rotors contain a coating of rust. Yet rust doesn’t necessarily pose a serious problem. In fact, rust commonly forms on the outer layer of a brake rotor.
Such surface rust stems from the abrasive effect of the brake pad, which leaves the surface of the metal vulnerable to corrosion. This light layer of rust usually disappears the next time you drive your car, literally scrubbed away by the action of your brake pads. Provided you use your car regularly, rust deposits should never get thick enough to cause real problems.
Yet corrosion can become problematic for those who allow their cars to sit outdoors undriven for prolonged periods of time. In that case, the relatively harmless surface rust may give way to corrosive rust. Corrosive rust penetrates deeper into the rotor’s metal. Even when removed, it leaves behind pitted and scored patches that reduce the effectiveness of your brakes.
Warping is something of a misnomer where brake rotors are concerned. A rotor possesses sufficient thickness and toughness to prevent its metal from literally deforming. When a mechanic discusses warping, they refer to rotor surfaces that are no longer perfectly flat. This problem has two main causes.
The first – and most common – cause of rotor warping involves brake pad material building up on the rotor’s surface over time. As brake pads heat up, the resins used to bind them together often break down. As a result, bits of fiber and resin attach to the surface of the rotor. Over time, as such patches grow thicker, they cause the rotor’s surface to become more and more uneven.
Rotor warping may also stem from variations in the density of the rotor. Less dense areas of the rotor wear down more quickly than more dense areas. As a result, dense portions of the rotor retain a greater height. This problem tends to be associated with lower quality rotors, which utilize less stringently controlled materials.
Low-quality rotors often suffer from another issue known as either galling, ribbing, or scoring. Here the problem stems from insufficient hardness that causes the surface of the rotor to become literally gouged by the friction of the pad. At first this may be hard to understand. After all, even the cheapest brake rotors have a much higher hardness than a brake pad.
Yet the relationship between rotor and pad changes as the two heat up. The friction of contact during periods of high-intensity braking causes the rotor’s temperature to climb. This friction softens the surface of the metal, making it more vulnerable to galling. As galling grows more pronounced, brake performance becomes bumpier and less efficient.
To ensure optimal braking, you should always invest in high quality rotors. Additionally, you must have your rotors regularly serviced by an experienced professional. For more information, please contact the brake pros at DeMers Automotive.