Brake Systems 101: Braking Systems in Cars Explained

Brake systems in cars are arguably the most important parts of a vehicle. Imagine you are driving down the road, and are approaching a stop sign; you press your foot on the brake pedal, and nothing happens. How would the vehicle stop, and what would happen? Modern vehicles are full of nearly unimaginable complexity, and thousands of parts are working together to ensure a safe, comfortable ride. But just how complex are the components of a braking system?

What are the Parts of a Brake System?

The braking systems of cars, trucks, and motorcycles are made up of a number of parts that translate the driver’s actions into physical force that stops the car. One, and possibly the most important of those brake parts, is your vehicle’s brake pads. Brake pads dominate a key brake part because they are the component that contacts and applies pressure and friction to a vehicle’s brake rotors – those flat, shiny discs that you can sometimes see just behind the wheels of some vehicles. The pressure and friction applied to the brake rotor is what decreases rotating speed and stops the wheel.

An example of a worn down brake rotor
Above: An example of a worn down brake rotor

Once the wheels stop turning, the vehicle stops moving, too. It is scientifically proven. Though the role of brake pads as braking parts is seemingly simple, the brake pads themselves are anything but. Stopping the rotation of such a fast body of mass introduces extreme amounts of heat to and stress into these pads. If you are a fan of motorsports, you may have seen the brake disk glowing bright orange, which is a result of the extreme heat that the braking system must cope with.

Examples of different brake pad types
Above: Examples of different types of brake pads

Think about it: would you want to grab and hold on to a heavy metal disc that was spinning really fast? Imagine slowly squeezing that disc until the vehicle rolls to a halt – it’s a thankless job, but brake pads do it repeatedly for thousands and thousands of miles without complaint. In other words, we completely entrust our lives into how smoothly, safely, and predictably we can stop the car with brake pads.

The reliability of the stopping device directly relates to the reliability of the automobile, and ultimately, the safety of the occupants. Brake pads are surely one of the most important and indispensable auto parts that any car cannot be without.

When to Replace Brake Pads

Unfortunately, there is no clear-cut schedule that tells you when it’s time to replace the brake pads. The deterioration of brake pads depend on several conditions such as the amount of time driven, climate, and frequency of stops, so you need to rely on your ears and the advice of an experienced automotive technician.

Most vehicles should have their tires rotated every 6 months or at least every 12 months, and that is a good time to have the brakes inspected as well. A mechanic can check the thickness of the pads and the condition of the brake hardware to spot wear.

Additionally, many modern cars have built-in wear sensors that scrape against a brake disc when the linings needed replacing. The light of these wear sensors usually turns on when the brake pads become thinner than 1.5mm (2/32 of an inch) in thickness. The driver will hear an annoying screeching sound when they apply the brakes (or when the brakes are released on some vehicles) as well.

An example of new and old brake pads.
Above: An example of new and old brake pads

Those sensors aren’t on every vehicle, so drivers should listen for squeaks, grinding (often a sign that brake pads are entirely gone), and other noises that indicate wear. Some minor noises can be eliminated by cleaning the brakes, but persistent, prominent noises usually mean the parts are worn beyond normal.

Other signs of wear include pulsations through the brake pedal, longer stopping distances, or when you apply the brakes your foot goes down further, closer to the floor. Because brake linings wear gradually, you may not notice the decrease in performance, so that’s where the experienced eye of a mechanic can help.

All cars have a brake warning light that comes on for a few seconds every time you start your car. If it comes on while driving, that probably means your brake system is low on fluid because of a leak or a problem with the brake master cylinder. Note that this is not the same warning light that comes on when you apply the hand- or foot-operated parking brake.

When to Replace Disc Brakes and Rotors

All cars and light trucks come equipped with front disc brakes, and most also have rear disc brakes, as well. Though, some budget-priced cars still come with rear drum brakes. With disc brakes, it has been common practice to just replace the brake pads and resurface the rotors on a lathe if needed so the surface is even and smooth.

Discs used to last through two or three resurfacings, but don’t be surprised when it’s time to replace the pads, you’re told you also need new rotors. The current ones may not have enough material to be shaved off with resurfacing, and may not be as durable or reliable.

Image of a disc brake.
Above: An example of a disc brake

In addition, repair shops are reluctant to resurface rotors because it adds time to a job and the quality of the work can vary by who does it and how skilled they are. Instead, it is faster, easier and more profitable for repair shops to just install new rotors along with new pads. It is replaced in most cases for commercial purposes, a sort of blind spot of amateur drivers.

With the above information in mind, hopefully you now better understand the importance of brake pads in a vehicle, and just how much passenger safety depends on well-maintained brakes and especially brake pads. If you notice any of the warning signs above, and are ready to begin shopping for high quality replacements, be sure to consider BE FORWARD’S wide selection of brake parts.


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