Why Do My New Brakes Squeal?

Have you recently replaced your brakes only to find they’re making an odd squealing sound? Don’t panic, it’s actually fairly common. If you’re scouring the web looking for answers to “why do my new brakes squeal?” Then great news, you’ve come to the right place.

One of the most common reasons that new brakes squeal is that there’s moisture on the rotors. When they get wet, a thin layer of rust will develop on the surface. When the pads come into contact with the rotors, these particles get embedded into them, creating a squealing sound.

Thankfully, in this article, we’ll cover everything you need to know about squealing brakes. We’ll first review the difference between the two main types of braking systems – drum and disc. Then, we’ll look at the most common reasons they make noise and provide a few simple tips to help quiet them down.

Drum vs Disc – What’s The Different?

Drum

This system gets its name due to it being housed in a cast-iron drum-like casing. When you press the brake pedal of a vehicle equipped with drum brakes, it sends hydraulic fluid into what’s known as a wheel cylinder.  Inside this cylinder are two pistons, that, when activated, push outwards.

As this happens, they press against what’s called a brake shoe, which consists of a curved piece of metal with a friction material attached to one side. When the shoes and the inside of the drum meet, it creates friction. This slows the rotation, and therefore the vehicle.

Drum brakes have mostly been phased out on newer cars.  However, some entry-level models still use them on the rear because they’re less costly to produce.  The issue with drum brakes is that they’re more complicated, which makes them more prone to maintenance. They also create more heat, causing them to wear out faster.

Disc

A disc braking system is similar to a drum, in that pressing the brake pedal sends hydraulic fluid to a piston, causing it to press against the caliper. A caliper is a clam-shaped device that fits around a portion of the rotor and houses the brake pads, which are similar to shoes.

Then there is the rotor, which is a metallic disc that’s attached to the wheel. As the wheel turns, so too does the rotor. When the pads press against the rotor, it creates friction, which is what slows the rotation. This interaction creates a lot of heat, which is why the rotors have small holes drilled into them, allowing the heat to disperse.

This system is less complicated and has fewer moving parts, which makes it easier to maintain, yet, more costly to produce. Most newer cars have a disc braking system due to the added stopping power they provide.

Now that you better understand the two main types of braking systems. Let’s look at a few of the most common reasons they might squeal.

Common Reasons Your New Brakes Squeal – And How To Quiet Them Down

Note: Before performing any repairs, you’ll first want to determine where the squeal is coming from. To do this, roll the windows down and brake, listening for which wheel is creating the sound.

Wet Brake Rotors

As mentioned earlier, wet rotors are one of the leading causes of squealing brakes, regardless of whether they’re new or old.  As the moisture sits, a thin layer of rust forms, and when your disc brakes operate as they should, this breaks off into small particles.

These particles then become embedded into the brake pads, and when they press against the rotor, it creates a squealing sound. Thankfully, this doesn’t last very long, and after a few hard stops, it should disappear. If not, the issue might be more serious.

This isn’t really something you can fix, since there’s no way to avoid every puddle, and not driving on days it’s raining isn’t feasible.

Lack Of Lubrication

This particular cause of squealing brakes only applies to cars equipped with a drum braking system and can happen on new or old brakes. As the pistons press the shoes outwards against the drum. If there’s not enough lubrication, they may let out a squealing sound as they scrape against the backing plate.

To fix this, remove the drum and apply a small amount of brake lubricant to the backing plate where the piston meets the shoes. You can usually tell where the issue is by looking for signs of scraping where the bare metal is exposed.   

Worn Or Thinning Brake Pads

While this doesn’t really apply to new brakes, it can still happen if you’ve replaced a caliper or rotor without swapping out your pads.  Most brake pads last between 25,000 to 65,000 miles, depending on your driving habits. 

Thankfully, manufacturers design brake pads with metal indicator tabs near the base.  When the pads become too worn or thin, they rub against the rotor, emitting a squealing sound. You should replace your pads immediately when this happens, or you’ll risk having reduced stopping power.

Depending on the quality of the pad, they should cost anywhere between $100 to $200 each at a shop (including labor). If you know how to replace them yourself, expect to pay between $50 to $150 for each pad. If you don’t, check out the video below for detailed instruction.

Glazed Brake Rotors

As rotors age, they develop imperfections, and if you get new pads, they won’t match the shape of these imperfections, resulting in a squeal. Thankfully, rotors usually last for between 30,000 to 70,000 miles.  If you haven’t yet reached this number, you’ll likely only need to resurface them rather than replace them.

Thankfully, many quick-lube style shops only charge $10-$15 to resurface (or turn) rotors. Which is a lot less costly than replacement, which usually runs around $500 or more. You can also do this yourself by removing the wheel and sanding down the surface of the rotor with 1,500-grade sandpaper.

Brake Pads High In Metal Content

Another reason your new brakes might squeal is if the replacement pads are high in metal content.  Most brake pads contain a mixture of different metals, including iron, steel, copper, and graphite. Depending on the ratios, they might squeal as they rub against the rotor. 

There are options made from organic material, such as glass, rubber, and heat-resistant resins. Though, these often lack the same stopping power of metallic pads.

The other option (and arguably the best) is ceramic brake pads, which consist of a combination of copper fibers and ceramic. These are the quietest and longest-lasting option, but they’re also the costliest.

If you can’t handle the squeal, you might consider swapping out your brake pads for ones with less metal in them.

Don’t Let Squealing Get You Down – Instead, Get Rid Of The Sound

Replacing your brake pads may be the solution you’re looking for.  However, if it’s not, don’t waste your money.  Instead, if a squealing sound is driving you crazy, consider the other options first, most of which are free or only require that you spend a small amount.

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Joshua Barrett

Josh Barrett is a writer hailing from the great state of Alaska. While describing himself in the third person is not his forte, writing about any and all things automotive – is. After 13+ years hustling in the exciting world of car sales, he took off to travel the world with his dog Teemo.