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It’s obvious that stopping your car is as important as starting your car, right? Without brakes, you’d have to glide to a stop (not controllable or predictable) or smash to a stop (hard on the car and probably the driver and passengers, too.)
So the need for brakes is obvious. Check.
But how brakes work and when they should be repaired or replaced may not be so obvious.
How brakes work
In modern cars, power brakes work through a combination of leverage, hydraulics, and friction. The leverage and hydraulics multiply the force you use when you push on the pedal so that the brakes receive much more force than you can produce by pushing alone. That combined force then creates friction by pushing the brake pads against the brake rotors in disc brakes, or by pushing the brake shoes against the brake drums in drum brakes, and that friction brings the car to a stop.
What’s the difference between disc brakes and drum brakes?
Drum brakes are enclosed in a—you guessed it—drum that turns with the wheel. Inside the drum there are shoes that push against the sides of the drum when the brake pedal is depressed. The downside of drum brakes is that if they get too hot, they don’t slow down the car sufficiently (or at all, depending on just how hot they get.)
Disc brakes consist of two pads on either side of a rotor (a rotor is a small-plate sized circle made of metal); when the brake pedal is depressed, calipers push the pads into contact with the rotors, causing friction that slows down the car. The advantage of disc brakes is that they’re exposed to the air rather than being encased in a drum, which naturally keeps them cooler so they operate effectively for longer.
Since the 1960s, front-wheel drive cars have disc brakes on at least the two front wheels. They may have drum brakes on the rear wheels to reduce cost.
What is a regenerative braking system?
In an electric or battery hybrid car, a regenerative braking system takes the energy created by braking and stores it in a battery. Because a regenerative braking systems reduce wear on brakes, some hybrid cars come with drum brakes rather than disc brakes.
When should brakes be repaired or replaced?
Disc brakes should be replaced when the pad has 1/8” or less remaining. If you’re not having your brakes visually inspected every 10,000 miles or so, another way to know when disc brakes need to be replaced is when you hear the squeal that occurs when the wear indicator—a small metal piece built into the brake pad—is exposed and starts rubbing against the rotor. When you hear the noise, you’ll want have the brake pads replaced within two to four weeks.
If you’re relying on the squealing indicator, be aware that sometimes indicators fail. If you notice that it takes longer to stop or that your brake pedal starts responding differently, it’s a good idea to get your brakes checked even if they’re not making any annoying noises.
With drum brakes, have them checked if they squeal or grind, or if brake performance or pedal responsiveness deteriorates.
How long do brakes last?
Brake life depends on a number of factors: how you drive your car, driving conditions (stop and go urban traffic vs. highway miles), type of brakes, and whether the brakes are on the front or rear wheels.
For disc brakes, the quality of the brake pad is also a factor. A good brake pad in normal driving conditions will last about 30,000 miles on front wheels, but it can vary from just 15,000 miles to 60,000 or more. On the rear wheels, brake pads can last up to two or three times longer.
What about brake rotors?
In disc brakes, rotors are the metal parts that the pads push against to create all that wonderful stopping friction.
Brake rotors today are made so thin that they need replaced every brake job or maybe every other brake job. And, if new pads are installed, it’s best to have a fresh clean surface for the new pads to stop against – a turned rotor or new rotor.
Brakes – Summary
You’ll save money in the long run—and increase your margin of safety—by having your brakes checked and any problems addressed as part of your routine auto maintenance.
Pfefferle Tire and Automotive Service is a two generation, family owned and operated repair shop. Our services include quick lube service, tires and auto repair, and routine maintenance. What sets us apart from other shops? Our technicians do not work on commission, so there is no need for them to oversell. We like to say, "We advise and you decide!"
Contact Pfefferle Tire and Auto Service to schedule your preventive maintenance appointment! (513) 829-1900
Written on Monday, November 26, 2012 by pfefferle
We are a certified dealer for MICHELIN®, BFGoodrich® and Uniroyal® Tires