When something wears out, you replace it. That’s a time-honored philosophy we learn as kids and use throughout our lives.
But on some things, the concept isn’t as straightforward as with others. If your dishwasher breaks, for example, you get a new dishwasher.
Your vehicle has four wheels, four tires, four brake pads. Logic would say that when one wears out, you replace it. That isn’t the case.
Should all brake pads be replaced at once? The short answer is that you should think of your brake pads in pairs: front and rear. If one brake pad has problems or wears down, you need to replace a set at a time.
Before we get into why that’s so, let’s start at the beginning, with how your braking system works.
What Brake Calipers Do
Brake calipers are an essential part of your vehicle’s braking system. Most of the vehicles on the road today use disc brakes to stop and slow the car. With a disc braking system, a car’s wheels have metal discs, also called rotors, attached that spin along with the wheel as you move. When you press on the brake pedal to slow or stop, calipers create friction against the rotor and slow the car down.
If you look at your braking system, the caliper fits over the rotor, resembling a clamp. Inside each caliper is a pair of metal plates – these are your brake pads. Known as outboard and inboard brake pads, they sit on either side of the rotor to put pressure on from both sides.
When you step on the brake pedal, brake fluid is released from the master cylinder. It creates pressure in the pistons of the brake caliper, which forces the brake pads against the rotor. Brake pads are made from high-friction material that slows down the rotor when contact is made. And since the rotor is attached to the wheel, the car slows down in the process.
There are two main types of calipers on today’s cars: fixed and floating.
Fixed calipers don’t move; they have pistons on both sides of the rotor. Fixed calipers are often thought of as high-performance, but they are more expensive than floating calipers. Fixed calipers, in general, have two or more pairs of pistons per rotor, but can go as high as six.
Floating calipers move in and out under pressure. One or two pistons will be on the inboard side of the rotor, pushing the entire caliper when the brake pedal is pushed.
Every time the brake pads come in contact with the rotor, they wear down a little. They become thinner and thinner until they can no longer do their jobs. The pistons continue to push the brake pads closer to the rotors, until they are fully extended. At this point, it’s time to replace your brake pads with a fresh set.
Which leads us back to our original question:
Should All Brake Pads Be Replaced At Once?
Brake pads on the front of your car will wear differently than the brake pads on the back. The reason is that your front brake pads actually do most of the work, with up to 70 percent of all braking action occurring in the front of your car.
When you step on the brake pedal, the weight transfers to the front of the car. The downward force is greater on the front tires, resulting in more friction between the front wheels and the road. With more force being applied to the front of the car, the action actually decreases in the back of the car. Braking is directly proportional to the amount of downward force applied to the wheels of your car.
Car manufacturers know this, so they create different braking grip between the front and back braking systems to improve overall performance with your vehicle. If equal pressure were to be applied equally, your back brakes would lock up earlier and cause your car to be squirrely under heaving braking conditions.
With more force being applied to the front of the vehicle every time you step on the brake pedal, it’s easy to see why your front brake pads wear out before the rear. This is why it’s possible you’ll have to replace your front brake pads more than your back.
But if you’ve ever looked at your brake pads, it is possible to have one side wear out faster than the other. If a brake caliper is defective, for example, it might cause the brake pad to wear quickly and need replacing long before the brake pad on the other side of the car. Why can’t you just replace the worn out brake pad? Why are they replaced in pairs?
So that both sides of the brake system are equal and work evenly to stop your vehicle. When you apply pressure to the brake pedal, it causes the brake pads to push against the rotors to stop the car. If the pads are uneven, it can stop one wheel faster than the other, making your car swerve.
How Often Should You Replace Your Brakes?
Different makes and models have different requirements. But it is important to note that your braking system is one of the most important parts of your vehicle to keep you safe and secure. When in doubt, replace.
Today’s cars are built with efficiency in mind. You’ll find different braking aids to push replacement farther out, meaning you can drive farther on every set of brakes you purchase. Some newer cars are installed with electronic brake force distribution, or EBD. The is a processing system that applies more braking power through the real wheel system, which will cause them to wear faster than other models.
You’ll also find cars with anti-lock brakes, or ABS. This is a cycling braking system where pressure is applied on and off in a series of bursts to both the rear and front wheels. This will increase brake pad wear, as well.
It’s Time For A Checkup
Of course, there are many ways your car signals brake pads are wearing down. We’ve written about them here and here. You might notice a flashing light on your dashboard. You might feel it as it becomes more difficult to stop.
Whenever you have a question about how well your brakes are working, don’t delay. Have them checked out from one of our mechanics to determine how safe they really are.