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My Car Doesn't Want to Stop!
by Kirk Swanda
Have you heard someone say, "My car doesn't want to stop", "My car is making a screeching noise when I am applying the brakes", or "My car is making a grinding noise when braking"? We hear these kinds of comments almost every day. These are typical comments associated with need for brake service. There are many components associated with the brake system.
The first and most replaced part in the brake system is the brake pads. On the front axle, there are typically brake pads, which work with disc brake rotors. The rear brakes are either pads, similar to the front axle, or brake shoes, which work with brake drums.
The front brake pads, which are inside the calipers, clamp down on the turning rotor, which is like a dinner plate, to stop the vehicle when the driver applies the brake pedal. The front brakes on most vehicles do approximately seventy percent of the braking of the vehicle. When the pads clamp down on the rotor, the friction caused by these parts rubbing on each other creates heat and causes the rotor to wear along with the brake pad. The brake pads, due to being the softer material, typically wear down quicker than the rotor, which will require the pad to be replaced typically twice in relation to one time for the rotor.
The rear braking system, which is on the newer vehicles, is similar to the front braking system. On the older vehicles and some of the new, the brake system on the rear axle is made up of brake shoes, which when the brake pedal is applied, the shoes, having the friction material, press against the inside of the drums, which are like a bowl. The rear axle takes care of the remaining thirty percent of the braking of the vehicle. Again, when the brake shoes push out against the brake drum, the friction caused by these parts rubbing on each other creates heat and causes the drum to wear along with the brake shoe. Like the brake pads, the brake shoes wear out faster than the brake drum and due to the rear brakes doing only about thirty percent of the braking of the vehicle, the brake shoes will last longer than the front brake pads.
When brake systems are checked, the rotors and drums are measured with a micrometer and inspected for heat cracks, distortion, damage and hard spots prior to resurfacing. This is to verify the thickness remaining of the metal on the rotor or drum. When they get too thin, this will cause the brakes to run hot, accelerate the brake pad wear, and reduce braking effectiveness. It can also lead to rotor or drum warpage and a pulsating brake pedal. The manufacturer of your vehicle specifies a minimum thickness for the rotors and the drums, which will allow for the metal to dissipate the heat build up of the friction from the brake pad touching the rotor or drum. The rotors or drums need to be replaced if they are too thin, have heat cracks, show distortion, damage or have hard spots. If the rotors or drums do not have any of these problems, they can typically be resurfaced on a brake lathe which cuts off the old surface and gives the new pad a good smooth surface to work with. Many of our customers will ask to have the rotors not be turned, but by not turning the rotors, the new brake pad will cause the brakes, when applied, to squeak.
The brake system of your vehicle is a very serious system for the safety of you and your family. This system is to be taken very seriously. You should always consult with a reputable automotive repair facility who employs quality service diagnostic technicians to have your vehicle's brakes serviced.
For any questions about your car, send your e-mail to: info@cba-suwanee.com
(Kirk Swanda is the owner and operator of Christian Brothers Automotive in Suwanee, Georgia)
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