Brake Pads: What Are They and When Do They Need To Be Replaced
By Victor Ivan Coll
Updated April 23rd, 2023
Ever search for a spot in the supermarket parking lot and want to crawl out of your skin knowing everyone is looking at you because of the squealing sound coming from your car? Maybe it happened as you rolled up to a traffic light, or in line at the drive-through. Maybe it’s happening now. You suspect the squeal is coming from your brakes because it happens whenever you step on the brake pedal. But what causes the noise? And what do you do about it?
Now, if you tend to be meticulous about your car care and insist on regular preventative maintenance, it is possible you do not relate with that scenario. If you present your car, truck, or SUV to a repair shop for inspection on a consistent basis, it may be that you have never heard your brakes sing out loud and out of tune. But whether you have felt the humiliation of noisy brakes or you have avoided the embarrassment, understand that the squealing sound can be a sign of a problem. It can also be normal. Either way, the noise is a tell-tale indication that your brake pads need to be replaced.
What are Brake Pads?
Common sense tells you that, if your car is going to go, it also has to stop. The brake pads, along with several other brake system components, are responsible for stopping a vehicle. They are made with special materials that maximize friction. When you step on the brake pedal, the brake system converts the kinetic energy of your vehicle in motion to thermal energy — in this case, the heat created by friction — which is used to slow or stop your car. Think of a fireman sliding down a fire pole. The kinetic energy of his body as it is pulled downward by gravity is converted to thermal energy by the friction between his arms and legs as they wrap around the pole. A more direct example would be the wheels on a bicycle. When the brakes are applied, the brake pads grip the sides of the bicycle wheel, creating friction that slows and stops the bike. The same principle is used in your car.
In a disc brake system, the brake pads are mounted inside a hydraulic clamp called a caliper. When you hit the brakes, hydraulic fluid in the master cylinder exerts force on the caliper which, in turn, squeezes the brake pads against the sides of a metal disc (called a brake rotor) connected to each wheel and tire. The resulting friction stops the rotation of the brake rotors and the wheels.
Over time, the friction materials in the brake pads wear away and a new set of pads must be installed. How quickly they wear out and how often they need to be replaced can depend on the what you drive (large trucks pulling heavy loads, for instance), where you drive (gravel road driving can cause premature wear), and how you drive (aggressive driving, riding the brakes, frequent sudden stops). Each of these factors can cause your brake pads to wear out faster than normal. Even the type of brake pad — the composition of the friction materials — can determine how long they will last. Brake pads will last 50k miles or more… or less.
How do I know when it is time to replace my brake pads?
So, how do you know when it is time to replace your brake pads? Your best bet is to have the brake system inspected regularly — at least once a year. A technician will check the life of your brake pads (indicated by their thickness) along with the operation of the rest of the brake system components and the condition of your brake fluid. If you do not take your car in for an inspection soon enough, however, you car will let you know when it is time for new brake pads. Here is a list of signs that your brake pads need to be replaced:
- Most vehicles made today feature a low brake pad indicator lamp that signals a driver that it is time for new pads by way of a dashboard warning lamp.
- Your brake pads are equipped with a device called a wear indicator. This little guy is responsible for the high-pitched squealing sound when you use the brakes. Not all squeals result from the wear indicator; sometimes small irregularities in semi-metallic pads can cause a similar sound. But that sound usually goes away shortly. The squeal from a wear indicator does not go away. If you ignore the squeal, damage can occur to the brake rotors.
- If you did indeed ignore the wear indicator squealing sound, a new sound is likely to develop: a metallic grinding noise. When the friction material is entirely depleted on your brake pads, the metal backing plate on the pads will contact the brake rotor. The metal-on-metal contact causes not only a grinding sound, but actual grinding of one or more of the brake rotors. This will likely require replacement of the rotors, instead of just the brake pads. And without the friction material intact, stopping power is greatly reduced.
- Shuddering or pulsing of the brake pedal or steering wheel during braking can be an indication of (among other problems) brake pads with uneven wear.
What if my brakes squeal constantly?
If, on the other hand, your brakes squeal all the time, not just when you step on the pedal, they could be telling another story. Brake pads are meant to wear out. Problems with other brake system components, although they happen occasionally, are not normal. Brakes that squeal or screech even when you let off the brake pedal could be the result of bad brake calipers that will not retract properly, or a clogged, crimped, or damaged hydraulic brake line.
Other brake-related problems that can occur include warped brake rotors that cause pulsating or shuddering, soft or spongy brake pedal (or one that travels too close to the floor or is too hard to press), or a faulty master cylinder.
What happens during brake pad replacement?
In addition to an inspection of the entire brake system, including the anti-lock brakes (ABS), a technician will replace the brake pads when they are at the end of their life. This involves lifting and supporting the vehicle off the ground, removing the wheels and tires, and replacing the brake pads. In the process, the caliper pistons need to be compressed to allow clearance for the new pads. The brake rotors are often resurfaced as part of the repair as well. If, when the technician measures the rotor thickness, it is determined that there is not enough material left for surfacing, new rotors may be recommended for replacement. The suspension system may also be inspected during brake pad replacement.
South Riding, Virginia — Ever search for a spot in the supermarket parking lot and want to crawl out of your skin knowing everyone is looking at you because of the squealing sound coming from your car? Maybe it happened as you rolled up to a traffic light, or in line at the drive-through. Maybe it’s happening now. You suspect the squeal is coming from your brakes because it happens whenever you step on the brake pedal. But what causes the noise? And what do you do about it?
Now, if you tend to be meticulous about your car care and insist on regular preventative maintenance, it is possible you do not relate with that scenario. If you present your car, truck, or SUV to a repair shop for inspection on a consistent basis, it may be that you have never heard your brakes sing out loud and out of tune. But whether you have felt the humiliation of noisy brakes or you have avoided the embarrassment, understand that the squealing sound can be a sign of a problem. It can also be normal. Either way, the noise is a tell-tale indication that your brake pads need to be replaced.
What are Brake Pads?
Common sense tells you that, if your car is going to go, it also has to stop. The brake pads, along with several other brake system components, are responsible for stopping a vehicle. They are made with special materials that maximize friction. When you step on the brake pedal, the brake system converts the kinetic energy of your vehicle in motion to thermal energy — in this case, the heat created by friction — which is used to slow or stop your car. Think of a fireman sliding down a fire pole. The kinetic energy of his body as it is pulled downward by gravity is converted to thermal energy by the friction between his arms and legs as they wrap around the pole. A more direct example would be the wheels on a bicycle. When the brakes are applied, the brake pads grip the sides of the bicycle wheel, creating friction that slows and stops the bike. The same principle is used in your car.
In a disc brake system, the brake pads are mounted inside a hydraulic clamp called a caliper. When you hit the brakes, hydraulic fluid in the master cylinder exerts force on the caliper which, in turn, squeezes the brake pads against the sides of a metal disc (called a brake rotor) connected to each wheel and tire. The resulting friction stops the rotation of the brake rotors and the wheels.
Over time, the friction materials in the brake pads wear away and a new set of pads must be installed. How quickly they wear out and how often they need to be replaced can depend on the what you drive (large trucks pulling heavy loads, for instance), where you drive (gravel road driving can cause premature wear), and how you drive (aggressive driving, riding the brakes, frequent sudden stops). Each of these factors can cause your brake pads to wear out faster than normal. Even the type of brake pad — the composition of the friction materials — can determine how long they will last. Brake pads will last 50k miles or more… or less.
How do I know when it is time to replace my brake pads?
So, how do you know when it is time to replace your brake pads? Your best bet is to have the brake system inspected regularly — at least once a year. A technician will check the life of your brake pads (indicated by their thickness) along with the operation of the rest of the brake system components and the condition of your brake fluid. If you do not take your car in for an inspection soon enough, however, you car will let you know when it is time for new brake pads. Here is a list of brake warning signs that your brake pads need to be replaced:
- Most vehicles made today feature a low brake pad indicator lamp that signals a driver that it is time for new pads by way of a dashboard warning lamp.
- Your brake pads are equipped with a device called a wear indicator. This little guy is responsible for the high-pitched squealing sound when you use the brakes. Not all squeals result from the wear indicator; sometimes small irregularities in semi-metallic pads can cause a similar sound. But that sound usually goes away shortly. The squeal from a wear indicator does not go away. If you ignore the squeal, damage can occur to the brake rotors.
- If you did indeed ignore the wear indicator squealing sound, a new sound is likely to develop: a metallic grinding noise. When the friction material is entirely depleted on your brake pads, the metal backing plate on the pads will contact the brake rotor. The metal-on-metal contact causes not only a grinding sound, but actual grinding of one or more of the brake rotors. This will likely require replacement of the rotors, instead of just the brake pads. And without the friction material intact, stopping power is greatly reduced.
- Shuddering, shaking, or pulsing of the brake pedal or steering wheel during braking can be an indication of (among other problems) brake pads with uneven wear.
What if my brakes squeal constantly?
If, on the other hand, your brakes squeal all the time, not just when you step on the pedal, they could be telling another story. Brake pads are meant to wear out. Problems with other brake system components, although they happen occasionally, are not normal. Brakes that squeal or screech even when you let off the brake pedal could be the result of bad brake calipers that will not retract properly, or a clogged, crimped, or damaged hydraulic brake line.
Other brake-related problems that can occur include warped brake rotors that cause pulsating or shuddering, soft or spongy brake pedal (or one that travels too close to the floor or is too hard to press), or a faulty master cylinder.
What happens during brake pad replacement?
In addition to an inspection of the entire brake system, including the anti-lock brakes (ABS), a technician will replace the brake pads when they are at the end of their life. This involves lifting and supporting the vehicle off the ground, removing the wheels and tires, and replacing the brake pads. In the process, the caliper pistons need to be compressed to allow clearance for the new pads. The brake rotors are often resurfaced as part of the repair as well. If, when the technician measures the rotor thickness, it is determined that there is not enough material left for surfacing, new rotors may be recommended for replacement. The suspension system may also be inspected during brake pad replacement.
Victor Ivan Coll | Victor Coll | Author: Victor Ivan Coll | Copyright 2023
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