Choosing A Car You Will Love

Brake Squeal: What It Means And How You Can Fix It

21 April 2015

Louis Castro

Your car's brakes are its most important safety feature. Without them, you wouldn't have much hope of bringing your car to a safe, controlled stop. So when you hear noises coming from your brakes, chances are you're worried about how it'll affect you from a safety standpoint.

The following goes in-depth about brake squeal, how it happens and how it can be reduced or even eliminated.

The Origins of Brake Squeal

When it's all said and done, your car relies on friction to bring it to a safe and controlled stop. The brake system provides that friction by pushing a set of brake pads lined with friction material against a disc made from stainless steel or a similarly hardened composite material. In addition to creating heat, this action also creates a negligible amount noise under normal operating circumstances.

The level of noise you'll hear during normal operation depends on the type and quality of brake pads used. For instance, a good set of semi-metallic brake pads will likely be noisier than a set of ceramic brake pads, since the former uses a high amount of metal fibers and powders in its construction. The more metal used in a brake pad, the noisier it'll be during everyday use.

As the pads wear down, it also brings a metal tab closer to contact with the brake disc. Once the tab strikes the disc, it delivers a high-pitched sound that indicates the need for a brake change as soon as possible.

What's That Sound?

Here's a rundown of the various brake noises you'll hear and what it means for your vehicle:

• Faint squealing – This is normal, in most cases. Depending on the type of brake pads you're using, you're bound to hear a little brake noise occasionally.
• Moderate squealing – You may hear this as the brake pads come close to the end of their working life. You may want to see how much friction material is left on the brake pads and prepare for replacement.
• Sharp, high-pitched squealing – Enough friction material has worn off the pads to bring the metal wear tab in contact with the brake disc. At this point, changing the brake pads becomes an absolute imperative.
• Grinding noises – Either there's little to no friction material left on the pads or other part of the brake system has come in contact with the discs.

Please Be Silent

The quickest and most effective way of silencing noisy brakes is to have them changed, preferably by a professional brake service. Although you can do the job yourself and pocket the savings, a professional mechanic is in a better position to spot other abnormalities within the brake system and even suggest repairs or replacements before it's too late.

As you change your brake pads, you may want to go for something a bit quieter:

• Ceramic pads – Unlike semi-metallic pads, ceramic pads use larger amounts of non-ferrous material. These pads are expensive when compared to their semi-metallic counterparts, but they're also quieter and less prone to making large amounts of brake dust.
• Non-asbestos organic (NAO) – Designed to replace the asbestos brake pads of old, these pads are made from a variety of organic non-ferrous materials, including rubber, glass and even Kevlar. They're quieter, but they also tend to wear down faster than semi-metallic pads.
• Low-metallic NAO – These pads resemble their NAO counterparts, except they incorporate a small amount of metal to improve heat transfer during braking. These pads are quieter than semi-metallic variants, but noisier than NAO or ceramic pads.

If you've just slipped on a set of new shoes, adding a small amount of brake anti-squeal compound to the back of the brake pads might do the trick. Not only does the compound help isolate vibrations that often contribute to noise, but it also protects the surface against rust and corrosion.

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