Brakes are the vehicle components that rarely get the attention they deserve. They’re often overshadowed by engine horsepower, how fast the car is, and how the car handles. But no matter what car you drive, brakes are there to bring it to a safe stop. They’re the safety parts that can save your or somebody else’s life.
Regularly inspecting the different brake parts means the braking system will serve its purpose. Most passenger cars rely on disc car brakes with the friction of brake pads and rotors slowing the car down. Older cars and trucks may still have drum brakes, counting on drums and shoes for the same job. And it’s these parts that wear down each time you press the brake pedal. So, changing them at regular intervals means carefree driving.
Bringing thousands of kilos going over 100km/h to a complete standstill, all within a matter of seconds, is no mean feat. Pressing the car brake pedal initiates a series of events. Since most vehicles are of the hydraulic type, they use hydraulic brake fluid compressed inside the master cylinder to generate pressure on wheel cylinders. This creates the needed mechanical force to thrust pads against rotors, or shoes against drum walls and slow the wheels down. Sounds relatively simple, but there a quite a few parts involved.
Disc brakes are what you’d find in most cars today. They get their name from the metal disc located just behind the wheels. This is attached to the wheel hub and rotates, or stops spinning with the wheels. Clamping the disc is the caliper. This has one or more pistons located in bores, and connected to the brake lines that carry the brake fluid from the master cylinder. Inside the calipers are the brake pads.
When you press the brake pedal, the brake fluid creates a significant amount of pressure to dislodge the caliper pistons from their bores and push the brake pads against the rotor. This will reduce speed or bring the wheel to a complete stop. Taking your foot off the pedal engages a return mechanism, so the caliper pistons and pads are pulled back, and the drop in pressure returns the brake fluid back into the master cylinder.
To make braking easier and safer, other critical parts also have vital roles. For instance, to create the needed pressure, a brake booster located between the pedal and master cylinder amplifies the force from your right foot needed to engage the caliper pistons. Without a booster, braking will be more tiring than leg day at the gym. Moreover, to prevent the wheels from locking under heavy braking, ABS and EBD modules and sensors lining each wheel work in sync to control the brake force applied to each wheel. This enhances safety and prevents related issues, such as loss of steering control.
Drum brakes consist of a backing plate that serves as the base for other components, a cylindrical cast-iron drum attached to the wheel, twin-piston cylinders, and brake shoes actuated by the cylinder pistons against the drum when the brake pedal is pressed. This too is a hydraulic setup requiring the pressure generated by brake fluid acting on the cylinders.
Disc brakes have become more common as they offer several significant advantages over drum brakes. They are less prone to brake fade, or the loss of friction on the rotor or drum, suffer less wear due to elevated heat levels, and generally offer more consistent braking regardless of speeds and road and weather conditions. And they withstand dangerous wheel locking better than drums.
This is down to tech and advanced materials. Rotors, calipers, and brake pads in car brake assemblies have become very efficient due to the use of materials resistant to heat, abrasion, and corrosion, as well as different designs that dissipate heat better. For instance, grooved, drilled and ventilated discs were once only seen in race cars, but lower prices mean they’re standard options on many newer road vehicles.
That isn’t to say that drum brakes don’t provide pros of their own. They have more brake force for the same size and need less pressure to actuate, so are often seen in heavier vehicles, and are cheaper to produce and buy. Maintaining them though is more difficult and time-consuming, and they can overheat and distort under high-speed braking, leading to loss of brake force and pronounced wheel vibrations. With the exception of the rear axle on cheaper compact cars (with drums easier to accommodate the rear handbrake), drum brakes are slowly going the way of dinosaurs.
Periodic inspections will determine the condition of automotive brakes and whether individual parts or the complete braking assembly need servicing or replacement. Most drivers, however, leave this for far too late until worrying signs start to show up. Brakes and car brake parts that aren’t up to scratch are an accident waiting to happen, so timely repairs are a necessity. Here’s what to look for in brakes that aren’t performing their best:
- Brake Warning Light in the Dash – If the brake light remains on even after releasing the handbrake, this can mean a range of problems, from an ill-aligned park brake, worn brake pads, or loss of brake fluid. If the light goes on when applying the brake pedal, this can mean issues with the master cylinder, or that fluid pressure is too low. Some cars have additional lights warning of advanced pad wear. In addition, damage to sensors and wiring in the ABS system, or the modules themselves, will also throw up a warning light on the dash.
- Screeching and Grinding Noises When Braking – This can be the metallic backing in the pads scraping against the discs, meaning the friction material is completely worn, leading to poor braking performance, and additional wear in the rotors. Grinding noises point to stuck caliper pistons, the buildup of debris and dust, warped rotors, and misalignment between pads and rotors.
- Excessive Vibration and Pulling to One Side – This can be an issue with brake lines and brake fluid, as well as warped wheel cylinders in drum brakes, and stuck caliper pistons in disc variants. it can also mean faulty return springs. Brake force needs to be applied equally for smooth braking that won’t affect the steering and ability to control the vehicle.
- Soft or HardPedal Feel – A soft or spongy brake pedal usually means issues with brake lines and fluid and is resolved by either replacing the fluid or bleeding the brake lines. The opposite, a hard pedal feel, often means a booster problem. Related issues, like a very low brake pedal (loss of pressure) and a pulsating brake (uneven wear in rotors), should also be checked.
- Burning Smells – This can be worn pads, overheating rotors, and damaged and stuck caliper pistons. The issue can also be from prolonged hard braking.
Other signs that deviate from normal braking performance should be checked promptly. Commonly, brake pads last roughly 50 thousand kilometres, and are usually replaced with brake fluid. Rotors last almost double that, around 100 thousand kilometres. These are just averages though, and factors like the vehicle, the average speeds, and how you drive all play a part. You should inspect your brakes for cracks, rust, debris, or fluid stains every six months even when there aren’t any warning signs.
Disc and drum brake components are sold through most automotive stores. Drivers can choose OEM parts recommended by the car manufacturer, These deliver the same braking performance when you got the car new. If you’re after more brake force or bite, consider the dozens of upgrade paths found in aftermarket brands. Either way, ensure that the brakes stop the car in the shortest possible distance and safely without affecting driver control.