Brakes, ABS, & TCS Systems

by David “Sam” Luttrell Jr, Absolute Automotive LLC

​     Does your steering wheel shake/wiggle while coming to a stop? Is there a vibration/buzzing in the brake pedal? Does the brake pedal kick back up or feel hard when you brake?
     What about that high-pitched squealing noise? These are all signs your vehicle's Brake/ABS/TCS system may need to be serviced or replaced.
     Let’s start by talking about the basic brake system components and how they function on your vehicle. When you apply pressure to your brake pedal, it is pushing a plunger in the Master Cylinder. That plunger is pushing the brake fluid through the brake lines going to all 4 wheels of the vehicle.
     The fluid going to the front brakes flow into caliper mounted behind each front wheel. The caliper has an inner and outer brake pad that squeeze the brake rotor.
     The fluid going to the rear of the vehicle flows into another set of calipers or wheel cylinders for drum style brakes. The brake pads squeezing the spinning rotor creates the friction that slows the vehicle. That friction also creates heat, and over time that heat warps the rotor.
     Warped rotors are the source of steering wheel shaking and wiggling while braking. The brake pads can be made out of different materials, some are semi metallic, and others are ceramic.
     The quality and price of brake pads vary tremendously. Cheap brake pads will squeak/squeal and prematurely wear into the rotors. Always insist on high quality brake pads, whether you’re a DIY-er, or having the brakes installed by a qualified mechanic.
     The Anti-lock Brake System (ABS) and Traction Control System (TCS) work together and sometimes are the same system. The ABS/TCS system is designed to keep the vehicle from skidding/sliding out of control while braking, and more sophisticated systems prevent wheel spin while trying to accelerate.       
     The ABS/TCS computer system uses wheel speed sensors that are usually mounted near or in the wheel hub/bearing on the front and rear of vehicle; some are mounted on the rear differential. The wheel speed sensor sends a signal to the ABS/TCS computer that shows how fast each wheel is spinning. When braking, if 1, 2 or all of the wheel speed sensors stop sending a signal to the ABS system abruptly (skidding/sliding), the ABS system activates and will pulse the brake fluid pressure to the corresponding wheel.
     This activation allows the tire to rotate instead of skidding or sliding, so you can regain control of the vehicle. This is the vibration or kick back you feel in the brake pedal.
     A failing wheel speed sensor or wheel bearing can send a false or no to the ABS system when the brakes have not been applied. This will sometimes turn on the ABS/TCS light and cause false activation during normal braking conditions. I mentioned the wheel bearing/hub assembly because some wheel speed sensors are built into the wheel bearing/hub assembly and cannot be changed separately.
 
     The purpose of this column is to help the average person have a better understanding of how their vehicles operate. Please feel free to contact me with any questions or concerns you may have at sam@absoluteautomotive.net or 816-847-5252. Absolute Automotive is located at 104 E. AA Highway, Grain Valley.
 

Photo credit: iStock photo.