Break noise is something very common in cars and it is easily one of the most annoying things you hear when you're driving. If your brakes are making noise, it tells you that something in your brakes may need some attention. You might only hear the brake noise as you step on the brake pedal, but sometimes it can be continuous.
In this post we are going to take you through the most common reasons why your brakes make noise, and also what you need to know in order to stop the noise.
In your car, the wheels are attached to something called a wheel hub and attached to the wheel hub is a brake rotor. When you drive your car, the break rotor is also spinning along with the wheel. Then there is a brake caliper bracket. This goes over the brake rotor. Unlike the brake rotor, your caliper bracket doesn't spin.
Then the brake caliper, the caliper get bolted onto the caliper bracket using something called guide pins (see picture below). Guide pins allows the caliper to slide back and forth as you apply the brakes. Inside the caliper you have the caliper piston. When you step on the brake pedal, what you are actually doing is compressing a small hydraulic piston near the brake pedal. And by doing that you're creating enough hydraulic pressure to move this brake caliper piston.
Brake pads get installed onto the caliper bracket and the brake caliper goes over the brake pads. When you apply the brakes, this brake caliper pushes the brake pads against the rotor. This causes a lot of friction and that's how the car slows down. And that is the basics. So now you know how the brakes in your car work, let’s get to the brake noise.
Basically, there are two types of brake noise, brake squeaking and brake grinding.
The break squeak - The number one reason why your brakes are making noise is worn out brake pads. See picture below, with these new brake pads, you can see here we have the backing plate. And then on top of the backing plate, we had the brake pad friction material or sometimes called as pad lining. And if you look at the end of the brake pad, here we have both ends tapered down at an angle.
Most new brake pads comes like this. This is called the brake pad chamfer. When the caliper begins to push the brake pads against the road, the brake pads begin to vibrate at a high frequency. This high frequency vibration is what makes brakes squeak. If the brake pad has a straight edge then these frequencies can be much higher so the squeak is going to be much louder. By having these chamfers the brake pad now has a softer contact pressure against the rotor. So you're gonna have reduced brake noise. But as the brake pad wears down, you can see the friction material finally comes to a point where it no longer has any chamfer. This is the time you normally starts heearing breaks squeak as you step on the brake pedal.
A chamfer is an angled cut on the friction puck's leading and trailing edges. Chamfers can control how the edge of the pad interacts with the rotors and can help prevent noise. Chamfers do this by making sure the largest possible edge of the pad makes contact with the rotor.
Along with this chamfer is another feature comes with your brake pad is the wear indicators. The steel clips are your wear indicators. So we have this very inexpensive brake pad thickness gauge. And if you measure the thickness of this brand new brake pad, we have 12 millimeters of friction material. But as the friction material wears down to the two millimeters, which is the minimum thickness of any brake pad, this way, indicators can screech against the rotor and make squeaking to let you know that the brake pads are worn out. But in high end cars, they don't have these steel clips. Instead they have brake pad wear sensors, so you wouldn't see this way indicators in high end brake pads. With very cheap brake pads, your brake pads can still make noise even if they're not worn out. And that brings us to the reason number two why your brakes make noise, which is very cheap work quality brake pads.
Brake pads are made of different materials such as organic semi metallic and ceramic. And those different materials have different properties, so they are used in different applications such as daily driving and racing. For example, many modern cars can see ceramic brake pads and they are usually more expensive to replace. So most people go for cheaper replacement brake pads when doing a brake job. But using non ceramic brake pads in a car that is designed to ceramic brake pads can easily make your brake start to squeak whether you're using the ceramic brake pads or organic brake pads. Any good quality brake pad comes with something called any vibration shims bonded onto the backing plate. You can see in this brake pad we have a nice fiber reinforced anti squeak shin molded onto the backing plate. This goes in between the brake pad and the brake caliper to absorb any vibrations and thereby reducing the brake noise, but in this cheap brake pad it is just a piece of steel held in place by two rivets, which may not work well all the time. And that is nothing compared to this brake pad where it doesn't have a sheet metal.
The next thing you have to look at is where the break pad can go in your brake caliper bracket. This brings us to the third reason why your brakes make noise, which is the worn out brake hardware. In your brake caliper bracket right where the brake pad gets installed. You can see these steel clips, this is your brake hardware. This allows the brake pad to slide in and out smoothly as you apply the brakes. But as your brake pads wear out, so do these brake hardware, and worn out brake hardware create too much play between the brake pads and brake caliper bracket allowing the brake pads to vibrate too much and that can make brake noise. When you buy cheap brake pads they come with just the brake pads. But when you buy some quality brake pads, they come with brake hardware. So when you install new brake pads, you should always install new brake hardware so your brake system acts like it is brand new.
Also your brake system is prone to collect a lot of brake dust, moisture and dirt. So without proper lubrication, your brake pads might get stuck with brake hardware. When you press the brake pedal, the brake pads can take the rotor. We already know that. But as you let go of the pedal, the brake pads come off the rotor ever so slightly so that your brake pads barely touching the rotor. So if the brake pads are stuck to the brake hardware, then they're not going to come off the rotor. Instead they keep rubbing against the rotor all the time, which can easily make a continuous brake squeak. When the brake pads are rubbing against the rotors, the friction material gets very hot and the contact area starts to glaze. This might make your brakes very noisy and the worst of all, glazing can lower the coefficient of friction on the friction material, so your car might even lose some stopping power. And that is pretty bad.
Glazing can also happen due to hard braking as well. Oftentimes, you can easily identify any glazing just by having a good look at your rotors. Look for any shiny spots than the rest of the rotor. And if you found any, you're gonna get a medium grit sandpaper and lightly scratch the area in a circular motion. Glazing can also happen in brake pads as well. So you're going to do the same with the brake pads with the sandpaper. This will even remove any contaminants that might be sitting on the brake pads. Not only the brake pads, but sometimes the brake caliper can get stuck. And that brings us to the reason number four why your brakes make noise, which is lack of lubrication.
Oftentimes when people replace the brake pads, they just lift up the caliber install the brake pads and that it. In order to keep your brakes working properly. This brake caliper is supposed to slide in and out very easily. And that job is done by these two guide pins. And that's why these guide pins need lubrication. To get to the guide pins. First you remove the two bolts that hold the caliber and these are your guide pins. To protect the guide pins from getting corroded and contaminated by dirt and moisture. We have these rubber boots sitting over the guide pins, but over the time the rubber seals may become weak so the dirt can get into the guide pins and the brake caliper can get stuck in place when the brake caliper gets stuck. So do your brake pads. So the brake pads start rubbing against the rotor all the time, which can easily make, well you guessed it, a continuous brake squeak. So to stop this from happening, you want to apply a decent amount of lubricant to both guide pins and also on the brake hardware where the brake pads get installed. Because the brakes are working at higher pressures and higher temperatures. It is very important to use the right lubricant on your brakes to see which lubricant works best for you.
Avoid Cheap Brake Pads The biggest problem with cheap brake pads is that sometimes they have uneven material distribution throughout the brake pad. So when these brake pads rubbing against your rotors as you press the brakes, your rotor is also going to start to wear unevenly.
Speaking about the rotors, the reason why your brakes may be making noise are the brake rotors, these wear out as your brake pads wear out.
If there are lot of grooves carved into the rotor, it creates an uneven surface between the brake pads and the rotor probably because of the use of cheap brake pads. Now this can also happen if you drive off road because the dirt and sand can get in between the brake pads and the brake rotor. Speaking about off road, anytime you drive off road there's a chance your rotors can get hit by rocks and get warped or sometimes even these dust covers can get bent and start scratching against the rotor. This can easily create a continuous or rhythmic brake noise. Now even if we installed brand new brake pads for this rotor, the new brake pads still going to grab on to these grooves as we apply the brakes. So it will start to make noise again. So in this case, you know resurface the rotor before you install new brake pads. In my case, I decided to go with brand new brake rotors. Speaking about brand new brake rotors. Most brake rotors are made of cast iron, because cast iron has good heat dispersion properties and also good friction properties. But the biggest issue with the cast iron is that they can rust over the time. This is not a concern for a car that is driven on a daily basis. But a big concern for cars that are not driven too often, because over the time the rust can build up to a pretty decent amount. So as you press the brakes, this layer of rust gets sandwiched between the brake pads and the rotor, and this could easily make brake noise.
Wear on brake rotors
All right, now it is time to move on to the worst brake noise of them all, which is brake grinding. If we hear a grinding noise from your brakes, that indicates something in your brake system is seriously worn out to a dangerous level. So you definitely want to take a look at your brakes before it's too late. Now that's what I'm talking about…..
This inside brake pad is so worn out that this is just a backing plate. This inside brake pad is in direct contact with the brake caliper piston all the time. This brake pad is always the first to be in contact with the rotor as you press the brakes. So it's very common for the inside brake pad to have more wear on it then the outside brake pad. That is why whenever you replace brake pads, you always want to install the brake pad with the wear indicator to the inboard side, not to the outboard side. Also, you can see right where the brake pads sit on the road, there's two ridges.
Now if you're going to install new brake pads on this rotor, then the brake pad will hit this radius and will start to squeak. So before you install the new brake pads, it is a good idea to use sandpaper to smooth out these ridges. But in our case, we’re replacing both brake pads and also the rotors.
And that takes us on the rear brakes. Brake noise can come from your front brakes or from your rear brakes. Now in this car, the rear brakes also disc brakes just like the front brakes. So everything we discussed, so if I apply to these brakes as well, but in some cars like this master, the front brakes are disc brakes, but the rear brakes are drum brakes. With drum brakes, instead of brake pads, we have brake shoes, instead of a brake rotor, we have a brake drum. Instead of a brake caliper piston, we have a wheel cylinder. So as we apply the brakes, this wheel cylinder pushes the brake shoes out allowing the brake shoes to squeeze against the brake drum. This creates a lot of friction, which slows the car down. So this is a slightly different setup to the disc brakes, but still the same principles apply in terms of how it works. So just like in disc brakes, worn out brake shoes, poor quality brake shoes, worn out brake hardware, lack of lubrication. And last but not least, worn out brake drums can make brake noise.
I like in disc brakes where the brake dust from brake pads can fly off in the air. Drum brakes are in closed systems. So most of the time the brake dust is collected inside the brake drum. So this brake dust can get in between the brake drum and the brake shoes. And this can make brake noise as you apply the brakes. So sometimes you can easily stop your brake noise just by cleaning your brakes. Speaking about the cleaning only use a brake cleaner whenever you clean brake pads, because this stuff is designed to use in brakes.
Since we are talking about drum brakes, one last thing which is often the most forgotten part in any brake system, which is the emergency brakes. This can be your hand brakes, foot brakes, or even electronic parking brake. And all this does is lock up the rear wheels. Now even if your car has rear disc brakes, most of the time, you still have drum brakes for the emergency brakes hiding behind your brake rotors. So you want make sure nothing is worn out or rubbing against each other, which can make brake noise.
That wraps up the top five reasons why your brakes make noise. So go check out your brakes before it's too late. up just like this. So if you haven't subscribed, definitely consider subscribing. I'll see you in the next one.