You are waiting at a traffic light and hear an oncoming vehicle slam on brakes with a loud squeal or screech. In some instances, it could be your vehicle making that noise when you stop at an intersection, traffic light or stop sign. You might think that there is something wrong with your brakes. This is not necessarily the case. We discuss some of the reasons why brakes squeal, and a lot of the time, there is nothing wrong with them.
It’s difficult to ignore brake squeals, particularly if the noise begins to worsen. However, there are several types of squealing caused by brakes.
Any moisture from rain or dew on the brakes can cause them to squeal in the morning. Moisture gets onto the disc or rotor surface, causing rust to form overnight. When brakes are applied the next morning, the brake pads scrape the rust off the disc surface. The front edge of each pad collects rust particles, causing a squealing noise when brakes are applied. This type of squealing can be eliminated if a car is stored in a drier place such as inside a garage.
Metal brake wear indicators are embedded deep inside brake pads. When a brake pad has neared the end of its life, the disc brake will start touching the metal wear indicator. This causes the brakes to squeal, warning the driver that it is time to replace the brake pads.
Wear indicators consist of small metal tabs made of hardened steel. They keep on squealing to the driver to replace the pads. However, if drivers continue to ignore those irritating sounds, then eventually the brake pads will become so thin, that, eventually, the metal callipers that hold the brake pads will be touching the discs themselves, causing a grinding noise. This is serious, because of possible damage to the discs, and may result in having to replace them.
Another type of squeal is caused by cheap brake pads with a high metal content. The metal is not evenly distributed but appears as large pieces in the pad material. It’s these metal pieces that cause the squealing sound when brakes are applied. You may have to hear this type of squealing for the rest of the life of the brake pads. This may be a long time, seeing most pads last about 50 000 to 60 000 km. Rather use brake pads that have a high percentage of organic material such as rubber, and resin. The metal particles in the brake pads can make it difficult to keep chrome or aluminium wheels clean.
Rear drum brakes can squeal when their shoe-to-backing-plate contacts are not properly lubricated. When these points are not lubricated, rust will set in. Lubrication of these points will remove this sound. Calliper slide pins should also be lubricated.
Slight leaking of brake fluid onto a rear drum brake can also cause a grinding noise first thing in the morning. This is because the brake fluid leak has dried from the last braking event. The resulting fluid residue causes a grinding noise until that has been worn way after the first few braking events.
A thumping noise from the rear of the car does unfortunately mean trouble and will likely be due faulty rear brakes.
Sometimes, a stone may land inside the brake and get stuck, causing a scraping sound. All it takes is to remove such a stone.
Having described these sounds, it is still difficult to decide exactly what sound is caused by what. At the first sign of some braking sound, it is better and safest to have it checked out.”
Most of the time, if your brakes squeal, it is best to have them checked out by professionals to be certain that, if there is an issue, they can sort it out in time.
Some more topics of interest relating to brakes:
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