Many drivers can recall a near miss saved by the quick application of brakes, while a smaller number remembers pounding the brake pedal too late and crashing. What does this subset have in common? Significant numbers of them will blame their accidents on brake failure. Most of them will be wrong.
The reality is drivers judge distances poorly, especially when traveling at freeway speeds. Typically, they have no idea how their brakes behave in critical situations and consequently believe crashes result from mechanical malfunction, when in truth their brakes performed as designed, but their following distances were too short for their speeds. The standardization of electronically controlled antilock braking systems (ABS), which prevent wheel lockup and skidding during heavy braking, has compounded the problem because ABS can make strange grinding noises when it activates, leading untutored drivers to suspect braking issues. When coupled with a human tendency to avoid blame, brake failure becomes the commonplace excuse for many crashes.
As a result, a significant percentage of the workload for forensic automotive investigators is brake-failure examinations. Despite the frequency of the claims, actual malfunctions in these complex systems are rare, although they can happen. Investigation requires the input of a trained automotive specialist who knows where to look for problems in braking components to find the telltale evidence of failure. Often issues associated with neglectful maintenance by owners impede brake function, especially when optimal performance is required.
When an investigator removes the brake pads, he can also inspect the pad surface. A smooth, reflective quality may indicate “glazing” caused by overheating, which decreases stopping power. Overheating may also result in brake rotor discoloration, and is usually caused by excessive brake “riding” by the driver.
Less commonly, brake failures may be caused by excessive rotor or drum wear. With the wheels removed for the pad inspection, the brake rotors or drums can then be checked for thickness, diameter, and warping to ensure that they are within manufacturer specifications. Rotors and drums need replacement less frequently than pads and shoes, but excessive wear can contribute to brake failure, especially if the pads or shoes are similarly worn.
Such a condition can contribute to an accident if a driver does not have sufficient stopping distance when facing a hazard. Once again, the way to avoid failures because of tainted or deficient fluid brake failures is proper preventative maintenance practices by the vehicle owner. This may include changing the brake fluid in accordance with manufacturer recommendations and regular brake bleeding to eliminate any air introduced into the system.
Potential Mechanical Problems