The Ultimate Guide to Car Brakes
Professional racers rely on an exceptional braking system to allow them to reduce their speeds closest to the turn for … Continued
Professional racers rely on an exceptional braking system to allow them to reduce their speeds closest to the turn for them to optimize their lap times. And while ordinary, everyday drivers take the modern car’s brake system for granted, paying attention to how it works, taking cognizance of the telltale signs of an impending brake failure, and keeping it in tiptop condition can literally spell the difference between life and death. You see, as efficient and fast as modern cars go, everything will be for naught if you cannot bring your car to a complete stop before disaster strikes (or striking disaster). Here’s your guide to this critical, albeit taken-for-granted component of your car.
The Anatomy of a Car Brake System
Depending on the type of brake system in your car, you can either have disc, drum brakes, or a combination of both. A conventional disc brake system is composed of the brake disc, otherwise known as the brake rotor, the brake caliper, and the brake pads.
- Brake disc or rotor
The rotor or disc is considered by many as the heart and soul of the modern car braking system. These are large metal discs that come in various designs. Race cars often have slotted rotors allowing for the better management of heat. The holes in a slotted rotor also facilitate the removal of water from its surface in wet weather. This helps provide for better braking performance even in wet and otherwise slippery conditions.
There are also brake rotors that are made of cheap metal. These are relatively inexpensive. Unfortunately, they don’t provide exceptional heat management leading to overheating problems. And as metal overheats it has the tendency to warp. Low-quality metal rotors are also not known to give you the short stopping distance you require. More often than not, you’ll end up fixing or even replacing a low-quality brake rotor more often than a premium high-quality disc.
- Brake caliper
The caliper is like a vise that grips onto the brake rotor when the brake pedal is applied. It contains hydraulic pistons that are connected to a series of hoses that supply the brake fluid. When the brake is applied, fluid is forced into the master cylinder and pushes the pistons in the caliper. This pushes the face of the brake pad towards the surface of the brake disk, clamping on the spinning rotor. Here’s the thing: the harder the clamping action of the caliper, the more heat it generates. And if you happen to have a low-quality brake disc, you know what it means.
- Brake pads
These babies are the ones that get in direct contact with the brake rotor. They are pushed by the caliper towards the brake rotor and these are the brake components that take the most abuse. As such it is important to go for brake pads that will be able to manage generated heat a lot more efficiently. You also cannot get a brake pad that is made of extra-hard compound if you live in freezing temperatures as the brake pads need to work at an optimum temperature to allow for the more efficient transfer of kinetic energy.
- Brake lines
As the name suggests, these are the hoses that convey hydraulic fluid to the brake caliper assembly. It is the passageway for that critical fluid so that the brake pads will be pushed against the rotors to help bring your vehicle to a stop. Unfortunately, the brake lines are some of the most problematic since they can get punctured, break, or get damaged leading to leaks. A leaking brake line is never a good thing. You won’t have the right amount of force to push the calipers and brake pads onto the rotors; in other words, stopping your vehicle may be exceptionally difficult.
Drum brake systems have essentially the same components as disk brakes, except that they are named differently and have a different action. The brake drum is equivalent to the brake rotor on a disk brake system. It is fixed to the car’s wheel. During braking, hydraulic fluid is delivered to the wheel cylinder which forces the brake shoes to move away from each other. This pushes the brake shoes against the rotating drum, slowing the car. Once the brakes are released, the brake shoes are returned to their starting position by the action of the return spring.
How Do Car Brakes Work?
Compared to other parts of the modern vehicle, the brake system is pretty simple with very few parts. Applying the brakes activates a master cylinder. This is also sometimes referred to as a brake or vacuum booster. The goal of the vacuum booster is to multiply the amount of force generated by your foot as it steps on the brake pedal. This makes it relatively easy to apply the brakes. You can just imagine how heavy it will be to depress the brake pedal without this booster.
Applying the brakes, as we have already mentioned above, transmits this ‘boosted’ force all the way to the master cylinder that is filled with your vehicle’s brake fluid. Modern cars always come with two sets of brakes, one on the front and another at the rear. Brake lines are distributed from the master cylinder all the way to the brake caliper assembly (for a disc brake system) and the wheel cylinder (for drum brake systems). These brake lines are also filled with hydraulic brake fluid. The master cylinder delivers just the right amounts of pressure towards the front and rear brake systems, giving you a safety net just in case one system fails.
Technically, with each step on the brake pedal you are actually forcing brake fluid into the calipers or wheel cylinders of your brake system. This forces the brake pads to move towards the rotors or the brake shoes to separate and make contact with the brake drum. This is what causes you to stop or to decelerate.
What are the Different Types of Brakes?
The disc and drum brakes are just two types of brakes found in cars. There are two other types of brakes and we’re going to look at them one by one.
- Disc brake
Most modern cars come with a disc brake system usually found in the front wheel of the car. It is composed of the rotors, calipers, and brake pads that are located on both sides of the rotor. When brakes are applied, hydraulic fluid is pushed towards the calipers bringing together the brake pads to clamp down on the rotor.
Disc brakes are preferred since they provide more stopping power than the drum type. Another reason is that the heat generated is more efficiently dissipated through the larger surface area of the rotor. The exposed components also improve dissipation. In the case of slotted rotors, heat dissipation is made even more efficient. Additionally, disc brakes tend to dry quickly in wet weather while also protecting the system against brake fade.
- Drum brake
In principle, drum brakes operate pretty much like disc brakes except that the movement of the brake shoes is outwards from the midline to allow them to get in contact with the brake drum. Drum brakes are less expensive than disc brakes and they are somehow a lot easier to repair or even replace.
Unfortunately, drum brakes don’t do well with heat as they tend to get hot the more frequent they are used. This effectively reduces their ability to stop the vehicle. Moreover, because of the inherent drum-like design of the system, water tends to collect in the interior, reducing its stopping ability and exposing it to the risk of corrosion.
- Emergency brake
While the parking brake can hardly be considered as a service brake for the simple fact that it is not operated or activated by brake fluid-filled lines, it does serve its purpose exceptionally well. Emergency brakes or parking brakes are connected to the service brakes, typically the pair located at the rear, by cables.
Different car manufacturers have different emergency brake mechanisms, majority of which come with a stick lever that is positioned in the center console usually beside the driver’s seat and between the front seats. There are also emergency brakes that are activated by another pedal usually next to the floor pedals. There are also those that are found next to the steering column. These are mostly used to keep the car stationary. In many ways, they function as emergency brakes when all the brake system fails.
- Anti-lock brakes
These are not actually brakes per se, but rather an advanced technology integrated into the design of modern brake systems. Anti-lock brake systems or ABS consist of sensors that keep track of the rotational speed of the individual wheels. In sudden braking, especially in wet road conditions, there’s a tendency for the wheels to lock up and the tires to skid because of the loss of contact with the ground secondary to the speed of the wheel. If skidding is detected, the ABS pulses the vehicle’s brake pressure rapidly on and off, reducing the rotational speed of the wheels and allowing the tires to reestablish contact with the road.
How to Maintain a Car’s Brake System
Because a car’s brake system is a relatively simple system, keeping it in tiptop shape should be easy. Here are some tips on how you can maintain the optimum operating performance of your car’s brakes.
- Check and maintain brake fluid levels
Make it a habit to check your brake fluid levels. That being said, you should know where your car’s brake fluid reservoir is located. The reservoir comes with level marks. Make sure that your reservoir is filled to the correct level. Perhaps more important is to use the right type of brake fluid. Car manufacturers always have their recommendations when it comes to fluids that work best with their systems. Check your owner’s manual for the specific type of brake fluid you need on your car.
- Replace brake fluid
Most car owners have this habit of simply topping off their brake fluids once the level is low. Unfortunately, condensation may infiltrate the fluid over time. If the brake fluid is contaminated, there’s a tendency that the master cylinder can get damaged. The wheel cylinders may also be affected. That said, you should replace or change your brake fluid every 25,000 miles or every 2 years, whichever comes first. You may need to check your manual as well.
To replace your brake fluid, locate the bleeder screw located at the back of each brake. Make sure you have the right tool for the job so you can easily open the bleeder screw without necessarily damaging it. Open the bleeder screw only slightly to allow the brake fluid to drain. You can attach a rubber hose to drain into a container so you don’t contaminate the ground under you or the car’s finish. While the brake fluid is draining, ask a friend to pump the brakes. At the same time pour new brake fluid into the brake fluid reservoir.
You know that you’ve done a good job if the fluid that drains through the bleeder screw looks like the same fluid you’re actually pouring in the reservoir. Once done with one brake, tighten the bleeder screw and continue working on the rest. Once all brakes are done, give it a few pumps to make sure you’ve got pressure on the pedals. Now’s also a great time to check for any leaks in the bleeder screws.
- Check the lines and master cylinder
The brake lines and the master cylinder are two essential components of the brake system that convey brake fluid from the reservoir to the individual brakes. As such it is critical that you follow the lines and look for any sign of leak. The joint between the brake lines and the master cylinder can be a good starting point, although the brake lines from the reservoir deserve some attention, too.
- Check and replace the brake pads if necessary
The brake pads are often the most abused parts of the brake system. They’re the ones getting heated up during braking. As such, they wear thin over time. Some cars have brake pads that can be easily seen from the outside. Some cars, however, have their brake pads hidden from view. You will need to remove the wheels to check the condition of the pads. The pads should have even wear and should still be at least 5 millimeters thick. Checking the brake pads can be done every 6,000 miles. If they need replacing, then you need to replace them with an appropriate type.
- Check and maintain the brake rotors or discs
The rotors should always be inspected together with the brake pads as these two components are basically what are always in contact when the brakes are applied. Rotors should have a smooth surface. If you see concentric grooves forming on the surface of the rotor, it usually means your brake pads are already slowly eating away at the rotor’s surface. In many instances, rotors can be resurfaced in a machine shop. The rotors are removed and smoothened using a grinder-like machine. If the damage is too extensive to be remedied by resurfacing, then you may need to replace the rotor. Always install new pads after getting the rotors resurfaced. This is to ensure that the grooves left by the rotor will not be transferred to the new surface.
Identifying Brake Problems
Keeping a strict maintenance schedule of your car’s brake system can save you a lot of trouble. Sadly, even a well-maintained car can easily break down. It’s a good thing there are always warning signs of an impending brake problem. Your knowledge of these can help you zero-in on a solution.
This can mean two things. First, your brake pads are long overdue for replacement. Second, there’s something else getting stuck on the rotors every time you step on the brakes. This could very well be the caliper itself or perhaps, more seriously, the metal part of the pads. Whatever the case, you should have it checked and serviced immediately.
High-pitched squeals emanating from the brakes as soon as you step on the pedal usually means your brake pads are wearing thin. Modern brakes are equipped with wear indicators that touch the rotors when the brake is applied.
The presence of brake dust that has accumulated on the pads can also produce that high-pitched noise. Other potential causes include rust or debris on the rotor surface and glazing of the brake pads secondary to excessive heat. Have it inspected by a professional.
- Loss of brake pedal pressure
When you apply the brakes, the pedal should feel relatively firm which actually increases as you push down towards the floor. If it feels rather spongy or if you can depress the pedal all the way to the floor with relative ease, you’re possibly looking at a leak in your brake lines. It can also mean that your brake pedal needs a little adjusting or it could mean your entire brake system is already failing. In this instance, you must pull over as quickly and as carefully as you can then get in touch with your mechanic or emergency roadside assistance.
- Vibrations on brake pedal
One of the reasons why you may feel as if your brake pedal is a bit ‘bumpy’ or ‘pulsing’ is that the brake rotors are already warped or worn usually because of excessive heat or friction. This should not be confused with the ABS of modern cars which can give you almost similar sensation. When in doubt, it is best to have it checked.
Whenever you take to the road, you want to feel safe. Keep your car’s brake system in its optimum operating performance and never go cheap on brake parts. Safety should be your first priority.
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