Hey guys, how's it going today?
I’m going to show you the top 5 reasons why your brakes are making noise. Brake noise is something very common in cars, and it is easily one of the most annoying sounds you hear while driving. If your brakes are making noise, it’s a sure sign that something in your system needs attention.
You might only hear the noise as you step on the pedal, but sometimes it can be continuous. In this video, I’m going to take you through the most common reasons for brake noise and, more importantly, what you need to know to fix it. That's enough talking—let's begin!
How Your Brakes Work (A Quick Anatomy Lesson)
First, let's understand the setup:
In your car, the wheels are attached to the hub.
Also attached to the hub is the brake rotor, which spins along with the wheel when you drive.
Then there’s the brake caliper bracket, which fits over the brake rotor. Unlike the rotor, the caliper bracket does not spin; it stays fixed.
Next is the brake caliper. This caliper is bolted onto the bracket using guide pins. These pins are essential as they allow the caliper to slide back and forth as you apply the brakes.
Inside the caliper you have the caliper piston. This is a basic hydraulic piston. When you step on the brake pedal, you compress a small piston near the pedal, creating hydraulic pressure to move this caliper piston.
Finally, we have the brake pads. These pads are installed onto the bracket, and the caliper sits over them. When you apply the brakes, the caliper pushes the pads against the rotor. This creates the friction that slows the car down. That’s all there is to it!
Diagnosing the Brake Noise
Now that we know how the brakes work, let’s get to the noise. Basically, there are two types: brake squeaking and brake grinding.
Today, I’m working on a 2007 Toyota Aurion that needs a complete brake job because both front brakes are making noise. The front left is squeaking, and the front right is grinding. Since the brake system in this car is similar to any other, this is the perfect opportunity to show you the reasons behind the noise.
Reason #1: Worn Out Brake Pads
The number one reason for noise is simply worn-out brake pads.
To show you the difference, here we have the old pads next to a genuine and a cheap aftermarket replacement. A new pad has the backing plate, and on top of that, the friction material (or pad lining).
The Chamfer and The Squeak
If you look closely at the ends of the new brake pad, they are tapered down at an angle. This is called the brake pad chamfer.
When the caliper pushes the pads against the rotor, the pads begin to vibrate at a high frequency, and that high-frequency vibration is what we hear as a squeak. If the pad has a straight edge, the frequencies are higher, and the squeak is much louder. By having the chamfers, the brake pad has a softer initial contact with the rotor, which reduces the noise.
As the pad wears down, the friction material eventually loses this chamfer. This is usually when you start hearing that annoying squeak every time you step on the pedal.
The Wear Indicators
Along with the chamfers, another feature is the wear indicators—those small steel clips. I have this inexpensive brake pad thickness gauge, and on a brand-new pad, we have about 12 millimeters of material. As the material wears down to the minimum thickness (around 2 millimeters), these wear indicators will screech against the rotor to let you know the pads are worn out.
Note: High-end cars often don't have these clips; instead, they use electronic wear sensors.
Reason #2: Cheap, Low-Quality Brake Pads
Your brake pads can still make noise even if they aren't fully worn out. This leads us to the second reason: very cheap, poor-quality brake pads.
Brake pads are made of different materials—organic, semi-metallic, and ceramic—and those materials have different properties for different applications (daily driving, racing, etc.). Many modern cars come with ceramic pads, which are often more expensive to replace. When doing a brake job, many people opt for cheaper, non-ceramic replacements, but using a pad not designed for your car can absolutely cause squeaking.
Any good quality pad comes with something called anti-noise shims bonded onto the backing plate. These shims fit between the brake pad and the caliper to absorb vibrations and minimize noise. However, on cheap pads, you might only find a piece of steel held in place by rivets, which may not work as well, or sometimes no shim at all!
Reason #3: Worn Brake Hardware
The next thing to look at is where the brake pad sits in your caliper bracket.
In your caliper bracket, right where the brake pad is installed, you see these steel clips. This is your brake hardware. They allow the brake pad to slide smoothly as you apply the brakes. But as your pads wear out, so does this hardware. Worn hardware creates too much play between the pads and the bracket, allowing the pads to vibrate excessively, causing noise.
When you buy good-quality brake pads, they always come with new brake hardware. You should always install new hardware with new pads so your brake system acts brand new.
The Danger of Sticking and Glazing
Your brake system is prone to collecting brake dust, moisture, and dirt. Without proper lubrication, your brake pads can get stuck to the brake hardware.
When you press the pedal, the pads grip the rotor. When you release the pedal, the pads must retract ever so slightly so they are barely touching the rotor. If the pads are stuck, they keep rubbing against the rotor all the time, which easily makes a continuous squeak.
This constant rubbing causes the friction material to get very hard, and the contact area starts to glaze. Glazing makes your brakes very noisy and, worst of all, it lowers the coefficient of friction, meaning you might lose some stopping power, which is dangerous.
You can often identify glazing by looking for shiny spots on your rotors. If you find any, use a medium-grit sandpaper to lightly scratch the area in a circular motion. You should do the same with the brake pads.
Reason #4: Lack of Lubrication
Sometimes the brake caliper itself can get stuck, which is our fourth reason for noise: lack of lubrication.
Oftentimes, when people replace pads, they just lift the caliper, install the pads, and that's it. For your brakes to work properly, the caliper is supposed to slide in and out very easily, and that job is done by the two guide pins. These guide pins absolutely need lubrication.
To access them, you remove the two bolts that hold the caliper. To protect the pins from corrosion and contamination, we have rubber boots over them. Over time, these rubber seals can weaken, dirt gets in, and the brake caliper gets stuck. When the caliper gets stuck, the brake pads are also stuck, and they rub against the rotor all the time, which can easily make, you guessed it, a continuous brake squeak.
To stop this, you must apply a decent amount of lubricant to both guide pins and also on the brake hardware where the pads sit. Because brakes work at high pressures and temperatures, it's vital to use the right lubricant; check your service manual for the best option.
Reason #5: Worn Out Brake Rotors
Speaking of rotors, the reason number five why your brakes make noise is too worn out brake rotors.
As your pads wear out, so do the rotors. You can see in this old rotor, there are a lot of grooves carved into the surface, probably because cheap brake pads were used. This creates an uneven surface. This can also happen if you drive off-road a lot, as dirt and sand can get wedged between the pads and the rotor.
Even if you install brand-new brake pads on this grooved rotor, the new pad will still grab onto those imperfections when you apply the brakes, and it will start making noise again. In this case, you need to resurface the rotor before installing new pads. In my case, I decided to go with brand-new rotors.
Rotor Materials and Rust
Most rotors are made of cast iron because it has good heat dissipation and friction properties. But the biggest issue is that cast iron tends to rust. This isn't a concern for a daily-driven car, but for cars that aren't driven often, the rust can build up. When you press the brakes, this layer of rust gets sandwiched between the pad and the rotor, which easily makes brake noise.
The Worst Noise of Them All: Grinding
Now it’s time to move on to the worst brake noise of them all: brake grinding.
If you hear a grinding noise from your brakes, that indicates something in your system is seriously worn at a dangerous level. You need to look at your brakes before it's too late.
This inside brake pad is so worn that there is just the backing plate left, which is now in direct contact with the rotor! Since this inside brake pad is metal-on-metal, it will start to wear the rotor down unevenly. It's a good idea to use sandpaper to smooth out these ridges, but in my case, I'm replacing both the pads and the rotors, so that is something I don't have to worry about.
Rear Brakes and Drum Brakes
Brake noise can come from your front or rear brakes. In my Toyota, the rear brakes are also disc brakes, so everything we discussed applies to them too.
But in some cars, like this Mazda, the front brakes are discs, but the rear brakes are drum brakes. In this drum system, instead of pads, we have brake shoes. Instead of a rotor, we have a brake drum. And instead of a caliper piston, we have a wheel cylinder. This wheel cylinder pushes the brake shoes out, causing them to squeeze against the brake drum, creating friction.
The same principles apply: worn brake shoes, poor quality shoes, worn hardware, lack of lubrication, and worn-out brake drums can all cause noise.
The Brake Dust Factor
Unlike disc brakes, where the dust flies out into the air, drum brakes are enclosed systems. Most of the brake dust collects inside the brake drum. This dust can get between the drum and the shoes, making noise as you apply the brakes. Sometimes, you can easily stop the noise just by cleaning your drum brakes.
The Most Forgotten Part: Emergency Brakes
I have one last thing, which is often the most forgotten part of any brake system: the emergency brakes (hand brakes, foot brakes, or electronic parking brakes). These lock up the rear wheels.
Even if your car has rear disc brakes, most of the time you still have small drum brakes for the emergency system hiding behind your brake rotors. Make sure nothing is worn out or rubbing against each other here, as that can also make brake noise.
That wraps up my top 5 reasons why your brakes make noise! Go check your brakes, and then check out my video on how to replace your brake pads and rotors. It’s jam-packed with useful tips and tricks, and I'll be putting a stop to all the misconceptions and doubts on how to properly and safely replace the brakes in your car.
