Brake squeal is more than just annoying. If you find yourself applying the brakes and hear a piercing noise like someone dragging their fingernails across a chalkboard, it can be an indication that something isn’t right. Not only can a squealing sound from the brakes be irritating, but it can also be dangerous.
Below, we discuss various causes of brake squeal and what you can do to correct the issue.
What is Brake Squeal?
Simply put, brake squeal is vibration. When you press on the brake, the calipers squeeze the brake pads against the brake rotors. This causes friction and slows the car down.
Since the brake pads are less than a millimeter from the rotors, there’s little clearance and a lot of pressure and friction. This means that when they’re under additional pressure, they may make a noise.
This can happen with brand-new brakes or brakes you’ve been using a while, and the sound doesn’t necessarily signal that you’re in need of replacement. Sometimes, brake noises are just annoying, but other times, they can also alert us to more serious problems.
Here’s why your brakes might be squeaking
#1. Worn or thinning brake pads.
The most obvious cause of brake squealing is worn brake pads. This is because brake pads are intentionally designed with a metal indicator that emits a high-pitched warning when they approach their minimum thickness.
That irritating screech is how you know it’s time to replace your brake pads. A thin layer of rust over your brake pads can make a similar squeaking noise, but that will usually go away after a few brake applications.
If the noise stays with you, be sure to get your brakes checked out right away. If you let the problem go and the persistent squeaking turns into grinding, it’s likely that you’re going to need new rotors along with your brake pads. This can more than double the cost of your next brake service.
#2. Dust or debris between your pads and rotors.
Another common cause of brake squealing is mud, brake dust, or other debris on the surface of your pads or rotors. This can happen in various driving conditions or if your car sits for a long period collecting dust.
In this case, a quick spray with cleaner or sanding down of the surface material will usually take care of the problem. It might also go away on its own after a few brake applications allowing the friction between the pads and rotors to wipe away the debris.
#3. Overnight moisture.
If you hear an odd-sounding noise first thing in the morning, it’s possible the noise is completely normal – especially if your car has been exposed to rain, snow, or humidity overnight. When moisture sets in on your brakes, a thin layer of rust can easily build up on the rotors.
This can cause a grinding or squealing sound when you apply your brakes. Fortunately, the rust buildup can usually be remedied with normal driving. You can also try parking your car indoors to protect your brakes from accumulating moisture.
#4. Your personal braking style.
Repeated hard and fast braking, especially at high speeds, can generate excessive heat, causing a smooth, hard glaze on your brake pads’ surface.
Glazing can also happen as a result of riding the brakes downhill, the constant friction causing a spike in temperature that exceeds the limits that conventional brake pads are designed for.
When brake pads become glazed, they can no longer generate the friction needed to stop the vehicle. They might also crack or fracture. As a result, you’ll need to have them replaced.
It’s worth noting that a mechanical or hydraulic failure in the brake caliper, causing the brake pads to rub against the rotor even when you’re not applying the brake pedal, can also be to blame for glazing. This is perhaps the most dangerous kind, since it happens without the knowledge of the driver.
To check for signs of glazing, run your finger along the surface of your brake pad to feel for a smooth and glassy finish.
When replacing glazed brake pads, you’ll also need to either clean or resurface your rotors and check the calipers and hydraulic system for mechanical issues or failure. If glazing becomes a repeated problem, you might also need to rethink your braking style.
#5. Metallic brake pads.
In some instances, squeaky brakes might be caused by the brake pad material itself. When it comes to brake pads, there are three types available: organic, semi-metallic, or ceramic.
Semi-metallic brake pads are perhaps the most common model on the market and consist of between 30% and 65% metallic elements like iron, steel, graphite, and copper.
When this type of pad rubs up against the rotor, it may cause the occasional squealing or grinding. The sound will usually stop once the brake pad wears down past that spot or layer, but if the noise bothers you, you might consider opting for pads with less metal.
While organic pads are by far the cheapest alternative, they offer inferior quality and durability, and also cause a great deal of dust. The other option, and arguably the best of the three in terms of quality and performance, is ceramic brake pads.
While costlier than their organic or ceramic counterparts, they also are the quietest and longest-lasting of the three.
#6. Lack of lubrication on drum brakes.
If your car has drum brakes, the squealing may be caused by a lack of lubrication at the contact points between the shoes and the drum. Without lubrication, the shoes start to scrape against the backing plate, causing a squeal.
You can usually tell where the issue is by looking for signs of this kind of scraping where the bare metal is exposed. Preventing or repairing squeaky drum brakes is as easy as applying brake grease to the backing plate where the piston meets the shoes.
#7. Loose Hardware.
Your braking system comprises many components, including hoses, clips, pins, calipers, pads, and rotors. When these parts get loose, they can vibrate and create squealing sounds.
How do I stop my brakes from squeaking?
The first step is to determine what is causing your brakes to squeak. If the brake pads are worn out, replacing them could eliminate the squeaking.
If there is debris stuck between the rotor and pad, cleaning it out could make a big difference. Applying a little grease to brake hardware such as slide pins can also help lubricate contact points and reduce squeaking.
A professional can help determine what is causing the squeaking and recommend repairs if necessary.
Is it okay to drive with squeaky brakes?
It depends on what is causing the squeaking. Moisture and heavy use may cause minor squeaking.
On the other hand, if the squeaking starts out of nowhere and seems to be getting worse, you should have the brakes checked as soon as possible to avoid friction causing costly damage.
What can cause brake squeaking when pads are in good condition?
If the squeaking can’t be attributed to worn-out brake pads, it could be caused by a few other things. Lack of lubrication or debris caught between the rotors and pads can cause squeaking.
If the brake components weren’t installed properly, it could mean there is friction where there shouldn’t be. Minor squeaking first thing in the morning could even be due to moisture collecting on the rotors overnight.
If it goes away after a few minutes on the road, there should be nothing to worry about.