If you haven't driven your car in a while, especially after a good downpour, then you might've noticed rust starting to form on your disc brakes. It's not out of the ordinary for surface rust to form on your brakes, but you want to make sure it doesn't interfere with your driving safety. The following explains when rust isn't a problem for your brakes and when it can become a concern.

Don't Be Afraid of Surface Rust

Surface rust is the most common type of rust your brakes can encounter. In most cases, surface rust appears on the surface of the brake rotors, although it could appear on other parts of the brake system if given enough time.

Just as the name implies, it's a thin layer of rust that typically forms after the rotors are exposed to moisture and the car sits for a few days. The most common cases of brake rotor rust usually occur after a rainy period, after which the vehicle isn't driven for a while. Even exposure to morning dew can set the stage for a little rust.

The good thing about surface rust is that it's relatively easy to remove. All you have to do is apply the brakes as normal and after a few stops the brake pads will wear the rust from the surface of the brake rotor. You may hear a little squealing as this happens, but it will also go away eventually. Most instances of surface rust, especially on parts of the brake system other than the rotors, can also be removed with a wire brush, brake cleaner and a clean cloth.

Be Wary of Severe Rust

Although surface rust is relatively benign and equally easy to remove, aggressive rust buildup caused by exposure to road salt, salt water and other corrosive elements can be especially troublesome. It can cause your brake calipers to stick in place, either freezing your car in place or robbing it of its braking ability. Severe rust can also cause the rotors to stick to their mounting points on the vehicle, making DIY brake rotor changes difficult.

Most surface rust appears in relatively small specks and splotches, whereas severe rust can leave thick sheets of rust on just about any vulnerable metal brake surface. If you see large clumps of rust on any part of your brake hardware, you may want to consider having those components replaced.