Just as important as making sure your car can go is making sure that it can safely stop.
Your brakes are critical for proper control of your vehicle, for your own safety, and for the safety of others around you on the road. But because of where they sit on the wheels and their constant use, your brakes are exposed to plenty of ordinary wear and tear as well as any bumps or collisions your car experiences.
For decades, power brakes were the standard in consumer vehicles. These systems amplify the force applied to the brake pedal and transmit it to the brake pads or shoes. Since the 1990’s, anti-lock brakes have become the standard on most modern vehicles because they provide additional control and a reduced risk of skids. And either of these braking technologies can be used in combination with the two main brake types: disc and drum.
Welcome back to the fourth installment of our Auto Care 101 series, where this month, we’ll be talking about brake systems. We’ll cover the basics for you, but if you’re interested in more detail, be sure to check out NAPA’s online Car Browser tool. As a proud NAPA shop, we offer not only stellar service and technical skill, but access to NAPA’s comprehensive library of automotive information. And as always, we’re here to answer any questions you may have—just come on in for a visit!
Power Brakes
An older type of braking, power brakes have been in use for roughly a century. Power braking systems ensure that you aren’t doing all the work of stopping the car with just your foot. To accomplish this, power brakes include a vacuum booster, master cylinder, and hydraulic lines that connect to the brake calipers or pistons.
The vacuum booster piggybacks on the work that your engine is already doing, using suction to create a low-pressure system inside its chamber. When you press the brake pedal, air flows into the other half of the chamber, moving the diaphragm and the input rod toward the master cylinder with more force than just your foot alone. The master cylinder contains hydraulic fluid, which carries the input rod’s force down the brake lines to the actuators.
Because the system relies on hydraulic fluid to transmit force, leaks anywhere in the system present a problem. Brake lines are especially at risk for leaks, so if you notice that your brake pedal feels mushy or your car takes longer to fully stop, it’s time to bring it in for a checkup.
Anti-Lock Brakes
Anti-lock brakes were initially deployed primarily on aircraft and heavy equipment in the 1950’s. As the technology developed, they became standard on consumer vehicles around forty years later, in the 1990’s. The reason for their rise in popularity is improved control and safety, particularly in emergency braking situations.
Whereas power brakes translate force directly to the brake actuators, anti-lock brakes use computer control systems to apply brake force intelligently for better results. In an emergency, when you need to stop quickly or when roads are especially slick, simply stopping your car’s wheels as quickly as you can could cause the tires to lose traction on the surface—which leads to a dangerous skid. Anti-lock brakes use sensors on the wheels to determine how much braking power to apply to each, and pulse the brakes quickly to avoid creating a skid.
One important change in driving technique that resulted from the introduction of anti-lock brakes is that cadence braking—that is, pumping the brakes repeatedly to prevent skidding—should not be done with anti-lock brakes. ABS can accomplish the effect of cadence braking on its own, so if you have ABS, remember to just apply the brakes firmly and hold them.
Drum Brakes
In addition to power or anti-lock brakes, there are two main types of brake systems that actually apply the force to stop your car’s wheels. The older of these types are called drum brakes, so called because they consist of a drum inside the wheel, and brake shoes on pistons inside the drum. Applying the brakes makes the shoes extend and press against the inside of the drum, slowing and eventually stopping the wheel.
You may be thinking that the brake shoes undergo a great deal of wear and tear, and you’d be right: they’re designed to eventually wear out, and are fairly simple to replace. A squealing or grinding noise coming from your car’s wheels indicates that the shoes have worn down, and that the drum itself is at risk of damage. If this is the case, bring your car in for a brake check at your earliest convenience. Also prone to wear are the springs that press the shoes against the drum. Your auto mechanic can check these for you during a routine brake checkup and let you know if they need to be replaced.
Disc Brakes
Disc brakes are a newer and, these days, more common type of brake. Some cars may have a mix of disc and drum brakes on their front and rear wheels, depending on whether they are front- or rear-wheel drive.
Instead of a drum and shoes, disc brakes have a disc or rotor, and calipers apply brake pads to the rotor to stop the wheel from spinning. One particular advantage of disc brakes is that they manage heat more effectively, since they have a lot of surface area and are exposed to open air. However, that exposure can also work against them, introducing road grime and the possibility of damage.
Like drum brake shoes, the pads on disc brakes are designed to wear down. The calipers themselves, which squeeze the pads onto the disc, can also wear down and lock or freeze in place, causing pads to rub against the disc constantly and affect your gas mileage. As with any other car part, bearings and seals can wear down, and the disc itself, or rotor, can warp or crack under extreme conditions.
Brake pads are relatively simple for a technician to replace, but other brake issues can be more complex. An experienced technician can examine your disc brakes and let you know if there are any issues that need to be addressed. Be sure to bring your car in for a check if you notice a squealing or grinding noise—as with drum brakes, this can indicate imminent damage.
Keep your brakes in good condition, and they’ll keep you safe.
Grit and grime from winter weather and road salt can be especially hard on your brakes. Now is a great time to bring your car in for a brake inspection, to ensure that you’ll be safe on slick winter and spring roads in Michigan as the weather warms.
Auto Tech Center’s certified mechanics provide top notch brake inspections and repair services, or anything else your vehicle may need, in the Ann Arbor-Dexter area. If you have any questions or concerns about your car, book an appointment with us today. We look forward to seeing you!
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