Introduction To Vehicle Disc Brakes

A lot of drivers don’t realize how far their car’s braking systems have evolved over the past few decades. Car manufacturers have been relentless about designing better, safer, more efficient systems. Beginning in the early 1970’s, most automakers integrated their platforms to accommodate disc brakes. Up to that point, most vehicles used drums. Today, we’re going to explore both types in more detail, so you’ll understand the differences between the two. First, let’s talk about how your car actually stops. How They Work In order to stop your car, the wheels obviously have to stop turning. This is accomplished through friction. Brakes apply resistance to the wheels, which creates the necessary friction to slow them, eventually bringing your car to a stop. How effective this process works depends upon how much your vehicle weighs, the force used to stop it, and the amount of surface area available on which to place resistance. Another factor is how well the system can take the heat generated by the friction and remove it. Discs Versus Drums Heat is a major reason why automakers have switched to discs. First, let me explain how the old drum-based units worked. Each wheel had a braking component that was contained within a drum. Shoes were used to press against them in order to slow the turning wheels. However, under extreme pressure (for example, constant b
raking while driving down a hill), heat would build up. The drums couldn’t take it, causing the components inside to lose their ability to slow the wheels. That’s a big limitation. Now, let’s look at discs. They work in the same basic way, but do so with rotors and calipers. Each caliper has 2 pads, flanking the rotor. When you need to stop, you hit the pedal which pushes the pads onto the rotors of each tire. The wheels slow and your car stops. The big difference is in the construction. The drums were enclosed and therefore, heat was basically trapped inside them. Rotors aren’t enclosed within anything. The heat generated by the friction of the clamping pads dissipates continuously, preventing overheating. Today’s Vehicles If you’ve ever shopped for a lower-priced car, you may be confused about why drum brakes are used in the rear wheels, given their tendency to overheat. The reason has to do with price. In essence, they’re cheaper. The good news is that vehicles stop by using most of the power of the front brakes. Today, nearly every car manufacturer builds their vehicles with disc brakes on the front wheels. So, you now understand how your car stops. Remember, these components wear over time and need to be replaced. If you hear squealing or feel a lag when you’re pressing down the pedal, visit an auto shop to have a technician take a look.