Understanding the Squeaky sounds While Braking

What's the Noise? How Severe Is the Problem?

Determine under what conditions and from what area of the vehicle you hear noise.

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Do you experience the noise only during the first few brake applications in the 

morning?

Do you hear the noise when braking at higher speeds, or when you gently apply the brake?

Does the noise appear to be a grinding or clunking sound, or a higher pitched squeal?

Does it appear to come from the front or rear of the vehicle?

Noise heard while braking is an indication of brake wear and the brakes should be inspected. Brakes are very much a safety item, and delaying repair is not a safe strategy. In fact, delaying repair can potentially lead to more expensive repairs because worn brake pads can wear down to the metal backing. 

When the squealing turns into a grinding, the brake rotors are likely being damaged (often requiring replacement).

What's That Squealing? How Do I Know if I Should Get My Brakes Inspected?

Before we assume the brake pads are worn, it’s important to understand that overheating brakes can cause a light squeaking, especially when the brakes are still cold. If there is sufficient pad material remaining, heat is a possible cause for squeaking.

Many car manufacturers incorporate some form of early warning system to alert the driver that the brakes need service. European cars typically use a warning light on the instrument cluster to alert the driver when it's time to replace the brake pads. A sensor deteriorates when the pad is worn to the minimum allowable thickness and then issues a warning light. Sensors are normally replaced when the brake pads are replaced.

Many Asian and American vehicles have a metal "finger" (sensor) that is an integral part of the brake pad. As the pad wears down, the sensor contacts the rotating brake disc (rotor), creating a high pitched squealing sound almost comparable to running your fingers down a chalk board. Brakes should be inspected periodically for wear and replaced as required. You should not rely on the visual or audio warning as your means of assurance that your brakes are okay.

Continually driving a vehicle until the friction lining of the brake pads is worn away will lead to expensive damage—your brakes might even fail. Anytime the brakes make an abnormal noise, they should be inspected and repaired before the braking system becomes compromised in any way.