51 --- Disc brake noise
Brake squeal. Squealing can be caused by dust on the pads, usually in combination with glazed pads, or other contamination from oil, grease, brake fluid or corrosion. Persistent squealing which cannot be traced to any of the normal causes can often be cured by applying a thin layer of high temperature silicone grease to the rear of the pads. Make absolutely certain that no grease is allowed to contaminate the braking surface of the pads.
Glazed pads. This is usually caused by high temperatures or contamination. The pad surfaces may be roughened using glass-paper or a fine file. If this approach does not effect a cure the pads should be renewed.
Pad material incompatible. BMW state that some non-genuine brake pads are made of poor quality friction materials which cause excessive squeal; these should be avoided.
Pad material. Friction material designed to cope with extreme temperatures may squeal at lower speeds, in town use.
Disc warped. This can cause a chattering, clicking or intermittent squeal and is usually accompanied by a pulsating brake lever or pedal or uneven braking. The disc must be renewed.
Brake pads fitted incorrectly. Inspect the pads for correct installation and security.
© April 2014