What is Causing My Brakes to Squeal at Low Speeds?
Why are your brakes squealing when lightly applied but stop when more force is applied?
What’s Happening & Why
As described in some owner’s manuals, the squealing noise is caused by high-frequency vibration of the brake pads against the rotating disc. Vibration is the unavoidable result of friction generated by the pads as the caliper clamps them against the rotating disc. Mounting the brake pads more tightly in the caliper would only make the noise louder.
Normally, the shims and the high-temperature grease between the pads and the brake caliper dampen and isolate most of the vibration. The level of vibration, however, is affected by outside temperature and humidity, by road conditions (mud, dust, and road salt), and by the condition of the brake pad material.
You should notice, as you keep your foot on the brake pedal and the vehicle continues slowing down, that the squealing noise decreases and then stops as the vehicle stops.
What Can Be Done?
If the squealing is abnormally loud, look for brake pad dust on the wheels, a strong indication of excessive brake pad wear. In any case, have the brakes inspected and checked for pad wear. If you find that repair is necessary, replace the pad shims and the high-temperature grease, and, if indicated, the brake pads as well.
From dealership records or from the customer, find out when the current pads were installed. If thickness of the friction material (compared to the wear indicator) shows that the remaining usable lining will not last until the next scheduled service, have the brake pads replaced.
Note: “Easy braking” customers, who usually get high mileage out of a set of brake pads, would find that these “softer” pads make less noise, and any difference in wear and braking performance would be undetectable.