Making sure your brakes are in proper working condition, and replacing worn parts like pads and shoes when the time is right, won’t just save you money in the long run. It can also potentially save your vehicle, or even your life in an accident. But how do you know when to replace your brakes' pads or shoes? What are they for? Let’s take a closer look at the how, what, and why of replacing brake pads and/or shoes on your vehicle.
Auto manufacturers install two types of brakes on passenger vehicles: disc brakes and drum brakes. Both use friction to slow your vehicle, but there are differences too.
Disc brakes use “pads” of specially engineered pieces of friction material made of organic, metallic or ceramic substances pressed against a rotor or “disc” when the driver steps on the brakes. The resulting friction slows the vehicle. Disc brakes are found on the front axles of all modern passenger vehicles and on the rear axle of many, too.
Drum brakes also use friction material, much like disc brake pads, but it is affixed to half-moon shaped “shoes” pressed against the inside of a drum when you step on the brakes. Their friction against the drum slows the vehicle. Drum brakes used to be common on all four wheel positions, but on modern cars and light trucks, they’re only installed on the rear axle.
Whether pads or shoes, both wear down with use, so it’s important to monitor their condition by having them inspected regularly. If allowed to wear out before being replaced, other components of the brake system may be damaged – especially the brake discs or drums. In addition to often costly repairs, driving with worn brake pads or shoes can result in unsafe driving conditions.
Every time you engage your vehicle’s brakes, a small amount of friction material is worn off the pads and/or shoes. Over time, the friction material will become thinner. If the pads or shoes are not replaced, the friction material will be worn off entirely, exposing the steel pieces that held the material. When these steel pieces come into contact with the discs or drums, excessively long braking distances and damage to the discs and drums will result. Look for these signs to know when to replace brake pads or shoes:
If a vehicle’s brake pads have wear indicators, a driver may notice a squealing, screeching or whining noise when the brakes are engaged. This sound is caused by a small metal attachment on the brake pad backing plate for just this purpose. Wear indicators work on the same principle as dragging fingernails across a chalkboard. When you hear it regularly while braking, it’s time to bring your car in to a brake specialist for an inspection. Note that not all brake pads come with this feature, so don’t rely on sound alone to assess your brakes’ condition.
When brakes are exposed to wet, damp conditions, such as after a rain storm, pads may exhibit a very similar screeching sound while braking. If a sound disappears after the first few times you use your brakes, that’s a good indicator that it was just a bit of moisture on the brake pads or shoes and not a sign they need to be replaced.
On disc brakes, you can also visually inspect your brake pads to know if it’s time to have them replaced, though it may require you to remove the wheels to do this. Looking down on the brake assembly or “caliper” holding the brake pads, you should see your brake pads compressed against your brake rotor. If the friction material on the pad or shoe is less than ¼ inch thick (about seven millimeters), consider having your brakes inspected, especially if it’s been a long time since your last inspection.
If you hear a deep, low noise that sounds like metal grinding or a rumbling growl, that can be a sign that not only are your brake pads worn away, but also your brake pads or shoes’ backing plates are making contact with the discs or drums. Since this metal on metal contact can very quickly cause even further damage in your braking system, bring your vehicle in to a service shop as soon as possible if you hear this type of noise.
Some vehicles have an indicator light on the dashboard that will signal when it’s time to replace the brake pads. Check your owner’s manual to see if your vehicle comes equipped with the low-pad warning system. Remember that if the light does come on, you’ll need to have your mechanic replace the warning sensors as well as the brake pads.
The real answer to how long brake pads and shoes can last will vary from vehicle to vehicle and from driver to driver. For example, if you tend to drive the most often in urban areas or in heavy commuter traffic, you’ll be engaging your brakes a lot more frequently than someone who drives in rural locations or on highways. Some people also tend to “ride the brake,” meaning they press and depress their brakes more habitually than other drivers, causing the brake pads to wear away more quickly. Brake pads and shoes are generally thought to be good between 30,000-35,000 miles in urban use. In less demanding situations like highway driving in light traffic, brakes may last 80,000 miles or more.
With a little attention and forethought, it can be easy to know when to replace brake pads and/or shoes on your vehicle.
There are a lot of car owners out there who don’t consider brake maintenance a priority—until something goes wrong. Do not make this mistake. When you hit the brake pedal, a complex network of parts springs into action. In order for the system to keep functioning properly, certain pieces must be replaced at regular intervals. Among those components, the ones that you’ll probably be switching out the most often are your brake pads.
In most modern automobiles, the front two wheels have a braking apparatus that depend on what are known as rotors: metallic discs found behind each wheel. Above each of these is a clamp-like device called the caliper. When you hit your brake pedal, the calipers start to close, squeezing the rotors from both sides. This action produces friction, which causes the wheels to spin more slowly until they come to a complete stop.
Brake pads are the removable surfaces that calipers use to make contact with the rotors during this process. These brake pads won’t last forever. (No car part does.) The friction mentioned earlier will inevitably wear them down over time. Let the brake pads get too thin, and your brakes won’t work as effectively as they should. For safety’s sake, it’s imperative that you get new brake pads installed at the first sign of trouble.
Should you notice any of these five red flags, ask an auto repair shop to replace the old brake pads ASAP.
Picture this: You’re out driving with the radio off and the windows rolled up. In the relative quiet, you hear a faint scraping, squealing, or buzzing sound. You also observe that, whenever you hit the brakes, that mysterious noise goes away, only to return again as soon as your foot comes off the brake pedal. What’s going on here?
Today, most—but not all—brake pads are manufactured with built-in “wear indicators.” The sole purpose behind these things is to emit that unpleasant screech you just heard. Wear indicators are metal tabs located near the top of typical brake pads. When the brake pad itself wears down to a dangerous extent, the indicator will scrape against the rotor. This creates a distinctive grating noise which warns the driver that his or her current brake pads are in danger of eroding away altogether.
In some cars, the brake pads fit snugly into a special holding device. Other vehicles keep them steady with clips, bolts, or pins. At all rates, the common goal behind these designs is to keep the brake pads from wobbling around. If they become loosened somehow (perhaps after a part of the surrounding hardware gets damaged), they’ll begin to rattle. What then results is a clicking sound that rings out whenever the brake pedal is pushed or released.
This problem has a name and that name is “brake fade.” More often than not, it’s the direct result of intentionally applying the brakes over a vast distance without bringing the car to a full stop. From time to time, such a maneuver might be necessary, particularly when driving down a mountainside or over a winding road. However, if this is something you do frequently—say, if you live in a hilly area where you must regularly drive downhill—it will take a toll on your braking mechanism over time. By forcing the brake pads to make contact with the rotors for a long, uninterrupted period, both components will heat up. In the process, their ability to generate needed friction against each other is reduced over time. As a result, you’ll find that your car won’t come to a complete stop as rapidly as it once did.
Your vehicle’s brake pads won’t always wear out at the exact same rate. Sometimes, those on one side will get thinner faster than their counterparts on the other side. Should this occur, the car may pull slightly to the left or right once you hit the brakes. Leave the problem unchecked, and you’ll put unnecessary stress on your steering rack (plus your vehicle’s ball joints, steering knuckles, and wheel bearings). Don’t risk it: Have a mechanic investigate the problem immediately.
Note that brake pads might not necessarily be the cause behind this particular symptom. It may also stem from such other issues as uneven tire pressure, a faulty wheel bearing, or malfunctioning brake caliper. With that said, if unevenly worn brake pads really are the culprit, two new sets should be installed in one session.
Does the brake pedal violently shake whenever you step on it? Your brake pads might be causing the problem. Brake pads are typically held together with a kind of binding resin. As each brake pad wears down, this adhesive gets hot and gets smeared across the rotor. Under ideal circumstances, it will form a layer that’s evenly spread over the disc’s surface. But if a brake pad gets overheated, the resin may not be distributed uniformly. Mechanics call this issue “glazing” and it can cause brake pedals to vibrate.
A pulsating brake pedal isn’t a trustworthy one. If this issue goes unchecked, your ability to brake safely could be compromised. When it comes to brake-pad upkeep, stay safe and don’t procrastinate.
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