What are brake pads and where are they located?
Your vehicle’s brake pads are major components in a disc brake system. A disc brake system consists of brake calipers, pads, and rotors. The rotors, also commonly referred to as brake discs, bolt onto the wheel hubs or axles, and spin at the same rate as the wheels. When you press the brake pedal, hydraulic pressure is transmitted to the caliper, which acts as a clamping device pressing the brake pads against each side of the rotor. The friction that this creates is what allows the vehicle to slow to a stop. In a nutshell, your vehicle’s brakes convert kinetic energy to thermal energy.
Most cars and trucks today have four brake discs, one for each wheel in the front of the vehicle and one for each wheel in the rear of the vehicle. Each disc will have a set of two brake pads, for a total of four brake pad sets on the vehicle – two in the front and two in the rear (for a total of eight brake pads). However, a lot of vehicles have rear drums instead of rear brake rotors. In this case, the vehicle will have two front brake rotors and two rear brake drums, and therefore it will have a total of two sets of front brake pads (for a total of four brake pads).
Automotive brake pads are made up of a friction material formula bonded together by resin and adhered to a backing plate. It is this friction material that makes contact with the rotor, which creates the friction needed to stop your vehicle. On the back side of the plate there is usually a shim, which is staked or glued on. The purpose of the shim is to create a barrier between the plate and the piston of the caliper, reducing noise.
Types of brake pad materials
There are three brake pad materials widely used in general automotive applications: semi-metallic, ceramic, and organic (non-asbestos). Which formula is best is often subject to debate. The truth is there is no such thing as the perfect brake pad as each type of friction material has strengths and weaknesses. Let’s touch on the basic pros and cons of each.
Semi-Metallic Brake Pads
Semi-metallic brake pads provide great stopping power and maintain good friction capability throughout its thermal capacity, providing better wear at high temperatures. Because of this, semi-metallic pads are more resistant to brake fade than other materials. Semi-metallic brake pads are the often the choice of original equipment material for many heavier vehicles such as pickup trucks, SUVs, and vans. The cons of these types of disc brake pads are that they are more aggressive and occasionally noisier than the softer brake pad material choices. Metallic brake pads tend to be harder on the brake rotors as well.
Ceramic Brake Pads
Most brake pads considered “ceramic” are technically ceramic enhanced, which means they consist of a mixture of metallic and ceramic fibers. The benefits of this material are that it can dissipate heat well, and can provide good stopping power while being less abrasive. This allows for longer pad life and less noise, while being easier on the rotors. Another nice feature of ceramic brake pads is the fact that the dust they create is light gray in color, which coincidently matches the color of most wheels. Ceramic brake pads however do not perform as well at high temperatures when compared to semi-metallic pads. They also tend to be the highest priced of the three.
Organic Brake Pads
Early automotive brake pads were originally created using asbestos, which we all know is a harmful material when inhaled. Modern organic brake pads (non-asbestos) are made from other natural materials such as glass, rubber, and Kevlar. The advantages of this type of brake pad is that they are very soft, which means they are quieter and easier on the rotors. Organic brake pads are also more environmentally friendly than other materials. Given the fact that organic pads are softer means they wear much quicker, and have less stopping power than ceramic and semi-metallic pads. Organic brake pads, although less common, are still used on some cars and trucks today. However, organic pads are frequently used more on motorcycles, ATV’s, and bicycles than on automobiles.
All vehicles have a recommended pad material suggested by the car or truck's manufacturer, which is determined by a variety of factors—such as vehicle size and designed use. Understanding the benefits and drawbacks of each material will help you decide which pad suites you and your car or truck.
How do I know my brake pads need to be replaced?
On the side of the brake pad (or pads) sits a wear indicator. The wear indicator is usually a small metal tab; when the pad wears down to a certain point this indicator comes in contact with the rotor, which causes the initial squealing “metal on metal” noise. Once you hear this extremely unpleasant noise, it is time to replace your disc brake pads. Not only will you be thankful, but those around will be as well. Many vehicles, especially European makes, use electronic wear sensors. These sensors will illuminate a service brake light in the instrument cluster when the pads wear to their discard thickness. It is important to replace worn pads as soon as they reach this predetermined thickness to prevent possible damage to your vehicle’s brake discs and to ensure proper braking. Being able to safely stop your car is equally as important as being able to start it.
Can I replace the brake pads myself?
Do-it-yourselfers with some prior brake experience can replace their own brakes. You will need to raise and secure the vehicle. Then you can remove the wheel and tire. From there, inspect the rotor for gouges and check the thickness of the brake pads. Then unbolt the caliper. Unbolt the caliper bracket and pry off the brake pads.
We recommend cleaning the brake pad slides with a wire brush and applying grease to the brake pad slides. Insert the caliper bracket into place. Start the bolt by hand and then torque the bolts to your vehicle's recommended specifications. Then place an old pad into the caliper and use a large C-clamp to reset the pistons. Insert the pads into the bracket and then place the caliper on. Insert the caliper bolts on by hand first, then torque them to your vehicle's recommended specifications.
For the final steps, reattach the wheel by sliding it into place. Start the lug nuts by hand and tighten the lug nuts preliminarily. Then lower the vehicle to the ground and tighten the lug nuts to your vehicle's recommend specifications. Be sure to replace the center cap and lug nut covers if they were removed.
Lastly, make sure you test your brakes. Pump the brakes until they feel firm. Then test the brakes at 5mph and 10mph. Once that's been completed, road test the vehicle.
