Why Do Brake Rotors Rust And When Does It Cause Problems With Your Car's Brakes?

15 June 2023
 Categories: , Blog


If your car has an open-wheel design that allows you to see your brake rotors, you may have noticed rust forming on the surface. Brake rotors are usually made out of materials that will rust because of exposure to water or moisture in the air, so rusted brake rotors are a common problem. Thankfully, driving your car regularly can prevent rust from damaging your brake rotors. To learn why brake rotors rust and when it becomes a serious issue, read on.

What Causes Brake Rotors to Rust?

When a car is manufactured, the brake rotors that are installed on the vehicle are usually made from cast iron or carbon steel. Both of these metals contain iron, which means they'll rust if they get wet. When you wash your car or drive over a puddle on the road, water will splash onto your brake rotors, and they'll start to rust.

If you live in an area where they put salt on the roads to prevent them from becoming icy in the winter, your brake rotors will rust more quickly. Road salt speeds up the rate at which metal corrodes.

Do Rusted Car Brake Rotors Cause Problems?

Rust on brake rotors is a common occurrence because they're routinely exposed to water whenever it rains and puddles form on the road. In most cases, rust on your brake rotors is not a problem. When you drive your car and use your brakes, the brake pads next to the rotors will push against them to slow your car down and bring it to a stop. This will scrape off surface rust, leaving the brake rotors with a clean surface.

However, rust on your brake rotors can become a problem if you don't drive your car for a long period of time. If you leave your car sitting outside for months without driving it, the rust will start to eat away at the surface of the rotors, creating pitted areas. This will damage your brake rotors and reduce your car's braking performance.

How Do You Know When Your Brake Rotors Have Been Severely Damaged by Rust?

When your brake rotors have been severely damaged by rust, your car won't stop as quickly. When the brake rotor's surface is heavily pitted because of rust damage, the brake pads can't make good contact with it when you step on the brakes. The pitted surface results in less friction between the brake pads and the brake rotor, so it's harder for the brake pads to slow your car down.

You can repair the damage by having your brake rotors resurfaced at a car brake shop. A technician will grind away a thin layer of your brake rotors to remove all of the pitted areas, allowing your brake pads to make good contact with the rotors again. It's a quick and inexpensive way to restore your car's braking performance.

Overall, rust on your brake rotors is usually not concerning since your brake pads will scrape away any surface rust when you use your brakes, even if you're driving at very low speeds. If your car has been sitting outside for a while, however, the rust can damage your rotors and cause them to become pitted. You'll need to have them resurfaced if they've been damaged by rust to restore your car's ability to rapidly come to a stop. If your car hasn't been driven for a long time and you think that rust has damaged your brakes, take your car to a vehicle brake service shop to have them inspected. You'll stay safer on the road by improving your car's ability to stop quickly.