The Ultimate Guide to Car Brakes (Car Brakes 101)

Ultimate Guide to Car Brakes

When you want your car to stop on a dime, you’ll need to install the best set of brakes. If you’re like most people, however, you don’t know much about car brakes other than that they help your car to slow down from high speeds and that they need to be replaced periodically.

In this article, we’ll break down every element of car brakes so that you will understand how to pick the right set of brakes and how to preserve your brakes for as long as possible.

While we can’t guarantee that you will be competent to install or maintain car brakes without any help by the time you are finished reading, we can ensure that your knowledge of brakes will be significantly more formidable than most people.

Brakes 101

In this section, we’ll explain the basics about your brakes so that you’ll know how they work and why.

From the perspective of the driver, you rely on your vehicle’s brakes for three main tasks:

  • Slowing the car down when it’s moving
  • Keeping the car stopped when it’s idling
  • Keeping the car stationary when it’s stopped on an incline

To accomplish these three tasks, vehicle brakes have an innovative design which allows the driver to apply stopping force to the wheels of the vehicle via a pair of discs. To understand how this works, you’ll need a quick lesson in physics and also automotive engineering.

The process of braking begins when your foot depresses the brake pedal, the force from your foot causes a piston which is attached to the brake pedal and filled with hydraulic fluid to compress.

The hydraulic fluid then magnifies the force from your foot and applies it to the brake pads when it decompresses.

The brake pads alongside the interior rim of the wheel well then clamp down on the rubber of the wheel. Because the rubber is spinning at high speed, the contact on the sides of the wheel starts to arrest the rate of spinning. This is known as braking.

If you have ever taken a physics class, however, you know that each force has an equal and opposite force. The force that equals the force from the hydraulic fluid in the breaking piston is the friction of the brake pads against the rubber of the brake.

When the brake pads cause friction by pressing against the rapidly spinning wheel, the speed of the wheel’s spinning drops and heat is released as a result. The heat which is released from braking is equal to the energy which you expended to depress the brake.

In a nutshell, brakes work by turning forward momentum into heat via friction. As momentum rises, the amount of resistance which will be necessary to slow down also rises. The heat then dissipates into the brake pad and subsequently the air surrounding your vehicle’s wheels.

Under ideal conditions, every time you brake, your vehicle slows down by an easily controllable amount. Because braking is a physical process, however, there are many opportunities for things to go awry.

You may already know that brakes perform worse when they’re old or when they’re at a very high or very low temperature.

The reason behind varying brake performance is that the brake pads are more effective at converting momentum into heat when they are not already hot.

When your brake pads are already saturated with heat from braking, the influx of new heat caused by additional friction has nowhere to go until the old heat radiates into the air.

This causes the brake pads to be less effective at slowing down the vehicle, and it also causes them to experience wear and tear. As a result, the physical properties of brakes are responsible for determining many of the salient factors to look for when you’re shopping for brakes.

What To Look For When You’re Shopping For Brakes

When you’re shopping for brakes, you need to consider several factors.

These factors include:

  • Peak Braking Force
  • Brake Fade And Heat Dissipation
  • Weight
  • Noise
  • Compatibility

In this section, we’ll discuss each of these factors in-depth so that you understand how the physics of braking impact the type of brakes that you should purchase for your vehicle in light of your needs.

Peak Braking Force

The peak braking force of a pair of brakes is defined as the maximum rate of arrest that those brakes can impart on a spinning wheel in a specified interval of time.

In simpler terms, the peak braking force determines how rapidly a pair of brakes can stop a vehicle. The higher the peak braking force, the faster the brakes will slow the vehicle regardless of how fast it is traveling.

Brakes with high peak braking force are necessary for vehicles which move at high speeds and carry heavy loads, like semi-trailer trucks.

For smaller vehicles like smart cars, the maximum momentum of the vehicle is not very high, so the peak braking force of the brakes does not need to be as high.

The peak braking force of a pair of brakes is determined by the mechanisms of the brakes and the brake pads.

Brakes which have more powerful hydraulic systems will magnify the force of your foot on the brake more than weaker systems. Similarly, brake pads with larger surface areas can generate more friction against the wheel over any interval of time.

Peak braking force is not necessarily a feature which you need to care about if you plan to drive a standard vehicle without any cargo in tow.

The standard brakes for the vast majority of vehicles are sufficient to arrest the forward momentum of the vehicle promptly enough to avoid accidents.

Furthermore, brakes with higher peak braking force tend to be more expensive to buy and more costly to maintain. Because brakes with high peak braking force tend to be heavier than other brakes, brakes with high peak braking force carry a penalty to your gas mileage as well.

On the other hand, if you plan on towing a lot of heavy loads, picking a pair of brakes with higher peak braking force will ensure that your vehicle can stop rapidly even when it has a lot of momentum.

Brake Fade And Heat Dissipation

Brakes vary widely with the amount of performance decay they experience when they are overheated. The fade of a brake is the rate at which a brake becomes saturated with heat and subsequently less effective at arresting the forward momentum of the vehicle.

Brakes with higher fade take longer to become saturated with heat, which means that they maintain the ability to impart their peak braking force for longer.

In contrast, brakes with lower fade become saturated with heat from friction rapidly, thereby losing their ability to arrest the vehicle’s momentum until they cool quickly.

In other words, the fade of your brakes determines how much braking you can do in one driving session before your brakes start to perform worse.

Similarly, the heat dissipation of a brake is the ability of the brake to shed heat into the surrounding atmosphere so that it does not become saturated with heat and less capable of slowing down the vehicle.

If a pair of brakes dissipate heat very efficiently, it won’t become saturated with the heat caused by frequent braking friction. This means that the brakes will be able to apply their peak braking force for longer before their performance starts to degrade due to being saturated with heat.

For vehicles intended for city use, brakes with a low fade rate will quickly become saturated with heat as a result of frequent braking. On the other hand, city-use vehicles seldom need to stop at their peak braking force because their momentum is rarely very high.

For vehicles intended for highway use or load towing use, brakes with a low fade rate may lead to disaster. This is especially true for brakes with poor heat dissipation, which may retain heat from prior rounds of braking for far longer than the vehicle’s operator suspects.

Thus, for vehicles which will be applying their brakes very frequently but at low speeds where the peak braking force isn’t as important, brake fade and heat dissipation are minor concerns which can be safely ignored, especially in non-commercial vehicles.

For vehicles which will travel on the highway and carry heavy loads, however, the fade and dissipation of the brakes are critical. In most cases, there is no tradeoff between heat dissipation and fade.

If you have the choice between a high fade brake and a brake that dissipates heat rapidly, however, you should opt for the fade.

Heat dissipation is influenced by a handful of factors which are not in your control like the weather and road conditions, so it is better to pick brakes which perform effectively even when they can’t shed heat.

Also read: Our guide to the top 10 best brake bleeder kits

Weight

The weight of your brakes is a significant consideration because it directly impacts your gas mileage as well as the effectiveness of the brakes themselves. The heavier your brakes, the worse gas mileage you’ll get.

Similarly, the heavier your brakes, the higher the peak braking force will be. Because more massive brakes tend to have more material than lighter brakes, more massive brakes are also likely to have a more favorable fade than lighter brakes.

While it is not always the case, more massive brakes are also more likely to have slightly less favorable heat dissipation than lighter brakes. If you want to purchase heavy brakes which buck the heat dissipation trend, they will be significantly more expensive.

In short, you should opt for the lightest brakes which can still arrest your vehicle’s forward momentum in a short period. Beyond a certain threshold, however, brakes also cost more as they get lighter.

The reason for this is that the most sophisticated brakes are made with lightweight and expensive materials which dispel heat especially effectively. Thus, try to find the lightest brakes which don’t require an additional fee unless you’re looking to splurge.

Noise

Brakes have an undeserved reputation for being noisy. When brakes are poorly maintained, they start to squeak or make other distressing noises.

Most brakes are silent or close to silent from the perspective of the driver unless they are damaged or have been specifically engineered to have a noticeable noise, like in the case of semi-trucks and industrial vehicles.

Thus, you should probably aim to find brakes which are quiet or silent unless the intentionally-added noise of the brake line is an essential safety feature for the class of vehicle that you’re driving.

Compatibility

You can’t fit a pair of brakes if they aren’t compatible with your vehicle. The brakes intended for a truck will not be compatible with your hatchback. This is especially true when the braking method of a pair of brakes differs from the standard disc-based design.

For most people, the primary concern is to pick brakes that are fitted for the diameter of the wheel.

For drivers of trucks or commercial vehicles, however, it may be essential to find brakes that have the correct modality. Drum-style brakes are conventional in dump trucks and similar vehicles. Most personal vehicles use the standard disc brakes.

Car Brakes FAQ

Now that you’re up to speed on how brakes work and which features you’ll need to look for when you’re shopping for brakes, it’s time to answer some frequently asked questions about brakes and braking.

Do Brakes Need Maintenance?

Yes, your brakes need maintenance. Specifically, your brake pads must be replaced at regular intervals to ensure that they can continue to arrest your vehicle’s forward momentum.

When you apply the brakes, the brake pads bear the brunt of the friction from the spinning of the wheel. The brake pads are designed to handle the heat from the friction. The heat isn’t the only issue, however.

Your brake pads are exposed continuously to the spinning motion of the wheel which erodes them over time, much like how sandpaper rubbed against a piece of plywood eventually loses its grain.

Brake pads can become so worn that they lose all of their stopping power entirely. Importantly, brake pads wear down very slowly over time, so there will never be a situation in which you pump your brakes and remain at the same speed.

Instead, you will slowly start to notice throughout many drives that your brakes need to be applied for longer and longer to slow your vehicle the same amount.

Brake pads are legally required to have minimum safe dimensions at which they can still perform their job.

This means that when you go into the shop to get your brakes repaired, the mechanic will check your brakes against their minimum safe dimensions and replace them if they are approaching their limit.

The hydraulic systems which connect your brake pedal to your brake discs seldom need maintenance. If the hydraulics are rusty or otherwise compromised, it will be noted in your yearly inspection and require your immediate attention.

How Long Should My Brakes Last?

For personal vehicles, your brakes should last for at least four years even with very heavy use. For commercial vehicles like semi-trucks, however, brakes must be replaced far more frequently. Some semi-trucks require brake replacements every six months.

A good rule of thumb is that the more massive the median load you are carrying in your vehicle, the more frequently your brakes will need replacing.

If you notice that your vehicle is not braking as promptly as it was before, however, feel free to get your brake pads replaced.

Why Do I Smell Burning Rubber After Using My Brakes?

Effective brake pads absorb the heat generated from the friction of the brake pads against the rubber of the wheel.

Ineffective brake pads become saturated with the heat on the surface of the brake pad to the point where that heat diffuses more easily into the rubber of the wheel than the air.

This is especially true when the air is already hot, and the rubber of the wheel is cooler than the ambient temperature.

In other words, if your vehicle is moving rapidly and your brakes are not high quality, slamming on the brakes can quickly saturate the brake pads and the air immediately surrounding them with heat, leaving only the rubber of the wheel to accommodate the excess.

When this occurs, and the rubber of your tires heats too rapidly, it can start to smoke, causing the air to smell like burning rubber.

Smoldering tires are signs that your brakes are not very good, but it can also signal that your tires are poor quality.

On the other hand, if you drive your vehicle out of an air-conditioned garage and then slam the brakes when you’re moving at high speed, some smoldering of the rubber is inevitable.

Under normal conditions, however, your brakes should never cause the wheels to smoke when they are being applied at less than their peak braking force. At the peak braking force, most wheels still should not smolder, but some may.

How Much Should Car Brakes and Brake Repairs Cost?

New brakes cost anywhere from $150 to $1000 per wheel depending on the vehicle and the brakes. If the brakes are especially light or unusually heavy, you should expect to pay more than the average.

The least expensive repairs tend to be brake pad replacements, which can be as low as $100 per wheel. In contrast, the most expensive brake repairs tend to be hydraulics work, which requires more shop time.

The thing to remember about brake pad replacements is that all vehicles need brake pads replaced. Don’t be surprised when your mechanic says you need more than one of your brake pads to be refreshed — your brakes operate on multiple wheels at a time.

On the bright side, brake pad replacements cost the same whether you have worn your brake pad to the metal or whether you have a few thousand miles left before direly needing a new set of pads.

In other words, your intuition about your vehicle’s needs may not mesh with the safety ratings of your brake pad, so you could save some money by waiting to replace them until it is necessary.

By waiting to replace your brake pads, you are not putting yourself in danger so long as your brake pads comply with the safety standards.

You pay the same whether the mechanic replaces a worn pad or a pristine pad, so you should try to get the most mileage for your money each time.

You may also like: Our guide to the best brake caliper wind back tool kits on the market

Are Brakes Easy To Install?

No, brakes are not easy to install. You shouldn’t try to fix your brakes or replace your brake pads alone unless you are a licensed mechanic who knows what they are doing.

Further more, brakes are essential safety features. If you botch an installation or a repair, you may harm yourself or other people by being unable to slow down rapidly enough.

Most people can’t approach brake repairs at home anyway because they can’t jack their car up to the height where it is comfortable or feasible to work on the brakes.

Rather than trying to improve your home brake repair infrastructure, save yourself a headache — and maybe your life — by taking your brakes to the shop.

Stopping On A Dime

Now that you’ve read our article on car brakes, you’re ready to make an informed purchasing decision, and you might have even learned something about the way your vehicle works as well.

Remember to perform all of your brake repairs with a licensed professional mechanic who can ensure that your brakes are up to the legally mandated standards.

Don’t forget to be wise when it comes to replacing your brake pads at the right time, and remember your vehicle’s intended uses if you’re shopping for new brakes.

Drive safely, and remember to maintain a safe distance between your vehicle and the one in front of it — even when your brakes are well-maintained and powerful.

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