Brakes are pretty much the most important safety device on your car. If you’ve ever partially lost your brakes in the past, you’ll agree that it’s not something you want to experience again. Inspecting your brakes twice a year for wear and damage can protect you and your passengers. Additionally, it will also help save you money by catching any damage before it becomes too costly.
Brake System Components That Can Fail
The master cylinder, the heart of the vehicle’s braking system, holds the brake fluid when it is not being delivered to the brakes through the brake lines. If brake fluid leaks because the master cylinder is worn or brake lines are plugged or broken, the fluid cannot be delivered, and the brake pads will become ruined.
The brake fluid itself can become dirty or contaminated as it draws rust-causing moisture and picks up other debris, or it can break down from excess heat. Clean brake fluid is either clear or slightly yellow, while dirty brake fluid may be brown or even black. Old and dirty brake fluid can damage ABS brake systems internally.
The brake lines connect to the master cylinder through a combination valve, which combines a metering and proportioning valve. It regulates the pressure on the front and rear wheels to make sure both sets of brakes are applied simultaneously. A malfunctioning combination valve may cause the wheels to lock up.
Brake pads and shoes can be made of ceramic, metal or organic materials, while the disc rotors and drums they press against are made of metal. Because the pads and shoes create friction to stop the car, they gradually wear down over time and may wear away completely, letting the metal of the calipers and cylinders they are attached to grind against the rotors and drums and damage them. Some pads have a metal strip attached that sounds a warning whistle when the pad becomes too worn, but this strip sounds only when the car is in motion and the brakes are not applied.
Brake vibration is where a shaking motion occurs when the brakes in a car or other vehicle are deployed. This can vary from a slight shaking to a quite severe shuddering, depending on the severity of the condition. It can also be known as rotor shimmying or brake pulsation.
Today’s vehicles are staying on the road much longer. The square cut seal in the caliper can become stiff and prevent the piston’s return. While no leaks are visible, this condition keeps the piston from retracting and causes the friction material to drag. The buildup of friction material on the rotor face then creates pulsations that would not have otherwise occurred.
Like golf club manufacturers, brake pad manufacturers are always looking for new space age materials to improve their products. These materials names may be throw around like buzzwords in a boardroom, but knowing what these materials can do can help you to make a more informed decision.
Premature ABS applications are mostly caused by speed sensor issues. Rust build up under the speed sensors is one common cause as seen on General Motors light-duty trucks. The speed sensor output voltage drops as it moves away from the tone wheel and is interpreted as a slipping wheel. Then as it moves a little further, an ABS variable voltage speed sensor code can be set.