Ask 10 drivers to name their favorite things about their cars and you may well get 10 different answers ranging from state-of-the-art infotainment systems to bountiful, easy-to-reach cup holders. But there’s one thing all drivers truly love about their cars, even if they neglect to mention it, or realize it – they stop.
There are numerous incredibly important pieces of equipment on your car that you probably never think of, and brake pads certainly earn their place on that list.
It’s unlikely that you envision these pads being squeezed against a rotor when you push the brake pedal, but you’d definitely notice if that didn’t happen courtesy of the instant, sheer panic instantly gripping your body.
It’s kind of like the light in the fridge – you forget it’s there until it doesn’t turn on.
So, because you’re thinking about it now, here’s a quick, introductory lesson on brake pads, including an answer to the question of what are brake pads made of. Call it food for thought the next time you roll up to a stop sign or red light and your brake pads, as they’ve done so many times before, once again save your life.
How car brakes work:
A brake pad is part of you car’s braking system, which, you know, stops your car. How do they do it? The quick explanation goes a little like this: Pushing your brake pedal sends pressurized brake fluid to a caliper, which squeezes a pair of brake pads together on either side of a rotor connected to a wheel. The friction created by the pads pushing on the rotor slows and (hopefully) stops your vehicle. There’s a good chance your vehicle has brake pads on at least its front wheels, if not all four.
What are brake pads made of?
Metals and ceramic materials are common in modern brake pads, though they used to make ’em out of Asbestos …
Asbestos you say!?
The dangers of asbestos weren’t always so well known, and the material’s properties actually make for a darn good brake pad. One of the most dangerous elements a brake pad must contend with is the potentially severe friction heat generated during contact with a rotor. Asbestos does a great job of dealing with that, so the material was widely used when disc brakes took off in the mid-20th century along with other pieces of equipment subject to friction, such as clutches. Asbestos was relatively inexpensive, too.
Believe it or not, brake pads are actually exempt from a limited federal ban on asbestos.
That doesn’t make me feel better.
Relax. We come bearing good news. The majority of brake pads used today aren’t made of asbestos. California and Washington state have even adopted laws prohibiting the use of asbestos in brake pads. These laws also call for a reduction in the use of copper aimed at reducing any potential of the substance breaking or from worn down brake pads and making its way into storm drains.
Copper is one ingredient in metallic or semi-metallic brake pads along with steel, graphite and other materials.
Metal-based brake pads certainly have what it takes to stop a two-ton machine, but they can do a number on rotors, they can be noisy, and they have a tendency to smear your sweet wheels with unsightly dust.
Ceramic brake pads, made of ceramic fibers held together by copper fibers, have become a popular alternative. They’re just as noisy as metallic or semi-metallic pads but you’d never know it because – and you’ll want to keep this in your back pocket for an interesting dinner table did-you-know tidbit – they produce noise at a range above what humans can hear.
Ceramics pads do produce dust, but less of it than metallic or semi-metallic pads, and what is produced is lighter in color.
If top-of-the-line performance is what you’re after, semi-metallic or metallic pads will probably be a better bet since they hold up better under friction, but a common driver who takes it easy on the brake pedal may get more life out of a ceramic pad, not to mention less wear on their rotors, in exchange for paying a little more upfront.
Non-asbestos organic brake pads are yet another option. They can be a pricier option than the alternative, and potentially wear quicker, but they’re pretty quiet and though they produce a good bit of dust, they’re as an environmentally friendly brake pad as you’ll find. They’re made of materials such as glass, rubber and the wishes of doe-eyed children for a better tomorrow.
Don’t cars have brake shoes, too?
Brake shoes are not the same thing as brake pads. Brake pads are used in disk braking systems, the most popular option in today’s market. Most cars have disk braking systems on at least their front wheels, if not all four.
Brake shoes are part of a brake drum. You’re most likely to find brake drums in older vehicles, trucks, and some entry-level models.
In a brake drum system, to keep it simple, pressurized brake fluid causes curved brake shoes to expand outward, creating friction with the inside of the drum to slow or stop a car.
You won’t find a variety of brake shoes like you will brake pads. They’re made of metal.
Perhaps disk braking’s largest advantage over drum braking is an open design. The closed brake drum isn’t good for limiting heat built up.
Written with contribution from AAA’s Car Doctor, John Paul.
To learn more about car parts and how they work, visit AAA.com/Car101.