How Do Car Brakes Work? | The Brakedown – Parts, Care & More

The average midsize car weighs around 3,300 pounds, or just under one-and-a-half tons. That’s a lot of weight – and it takes a LOT of force (and time) to stop all that weight, especially moving at highway speeds. Enter, brakes. We rely on them constantly as we drive, so if you find yourself wondering, “how do car brakes work,” you’re not alone. Today, we’re going over the different parts of car brakes – how those parts work together to keep you safe – and how to best care for your brakes. 

When you hit the brakes, you press down on the brake pedal. The pedal pushes on the master cylinder, multiplying the force you apply to the pedal and compressing the brake fluid. As pressure builds in the master cylinder, it transmits to the brake calipers (on disc brakes) or wheel cylinders (on drum brakes) through brake lines. On disc brakes, the brake calipers squeeze the brake rotor, forcing the brake pads against the rotor and stopping the vehicle. On drum brakes, the wheel cylinder presses the brake shoes against the inside of the brake drum, which then press into the rotor, stopping the vehicle. 

Brakes stop cars through the friction generated by the brake pad/shoes pressing against the rotors. Wheels rotating thousands of times per minute (at highway speeds) generate a lot of heat when pressed against something suddenly. Brake pads/shoes absorb and dissipate that heat. 

Although drum brakes were the industry standard for decades, disc brakes took over in the 1970s and 1980s and are now more common than drum brakes. Disc brakes have an open-air design, allowing them to dissipate heat more efficiently than drum brakes, which can trap heat in the metal drum. 

Some cars still use disc brakes on the front wheels (where most of a vehicle’s stopping power comes from) and drum brakes on the rear wheels as a cost-saving measure. If you’re curious about your car’s brakes, you can check the owner’s manual and see what type of brake your vehicle has on the front and rear wheels. 

How Long Do Brakes Usually Last?

Long story short, it depends – brake pads, the most commonly replaced brake part, can last anywhere from 25,000-65,000 miles. The average person drives around 12,500 miles a year, so most people replace their brake pads once every two to five years. 

Automakers commonly use three types of brake pads:

• Non-metallic or organic pads. These are the softest – and often, least expensive – brake pads. Unfortunately, they also generally wear out the fastest and create a significant amount of brake dust, making them the least desirable option for most drivers. They have an advantage over semi-metallic brake pads in cold weather, but the rate they wear makes them unsuitable for most drivers.
• Semi-metallic brake pads. Semi-metallic pads are the industry stands. They’re a lot more heat-resistant than organic pads, but slightly less efficient in cold temperatures. Semi-metallic pads are generally middle-of-the-road when it comes to pricing. 
• Ceramic brake pads. Ceramic brake pads offer the best performance – for the highest price. They do require some warmup, meaning that for most daily drivers they aren’t great – but for certain vehicles, like race cars, they’re a must-have. 

When Should I Change My Car Brakes?

As a general best practice, we recommend having your mechanic check your brake pads at least once a year. They’ll be able to tell you when you should spring for a replacement. 

You may also want your mechanic to check more than just the pads. Roughly every two years, you’ll want to flush your brake fluid. Brake fluid is a vital part of the braking system, so staying up-to-date with fluid replacements is incredibly important. Unfortunately, brake fluid is also highly toxic, so relying on a mechanic to change it will generally serve you better than attempting a fluid flush and re-up yourself.

To monitor the health of your brake pads, keep an eye (and ear) out for the following:

• A “screech” while braking. Brakes may “squeak” if the pedal can use some oil, but when squeaks become squeals, it’s time to take your car to a mechanic. Brake pad manufacturers specifically design brakes to “screech” as a warning for drivers, so don’t ignore it!
• Vibrations while braking. Vibration while braking can indicate rotor warping or damage, which typically requires rotor resurfacing or replacement to fix. 
• “Soft” braking. If you need to press the pedal more than you’re used to for results or your brakes feel less responsive, take your car in for a check-up. “Soft” brakes could signify issues in the master cylinder, brake lines, or degraded brake fluid, so ask your mechanic to check the entire braking system. 
• Listing to one side while braking. If your car lists left or right when you brake, it’s possible that your calipers aren’t working quite right.

Paying attention to your brakes – and taking your car in if you think something’s wrong – will help you (and everyone around you) stay safe on the road. 

How Can I Make My Brakes Last Longer? 

If you want to get the most out of your brakes, consider:

• Driving the speed limit. The faster you go, the more energy your brakes have to dissipate – and the faster they’ll wear out. 
• Practicing good brake maintenance. Following the steps we’ve listed – like checking the quality of your pads and flushing your brake fluid biannually – will help other brake parts last longer.
• Going for a slow stop. Sudden stops put a lot of stress on your brakes. The more time you take to stop, the less your brakes have to work – and wear out.
• Applying pressure one pedal at a time. Driving with one foot on the gas and the other on the breaks tends to result in drivers “pulsing” their brakes a lot. As a result, playing the pedals with one foot often results in longer-lasting brakes. 
• Keeping it light. The heavier your car is, the more your brakes have to work to stop it, so keeping your car light can help preserve your brakes. 

There you have it! A rundown of how cars brake, from parts to brake care tips and tricks. Interested in learning more about caring for your car? Stay tuned to the Carvana blog!