My car has rusty rotors: should I be worried?

April 15, 2021

You've probably seen brand new cars with gorgeous shiny metal discs behind the tire rim - this is what's called a rotor in the car braking system. However, if you look at your own car and your rotors aren't gleaming brightly at you, is that a cause for concern?

Why rotors become rusty

First of all, did you know that a lot of your car parts are made of steel? The brake rotors, calipers, and some elements of the brake pad are made of steel because of its toughness and durability. Steel isn't considered a pure metal because it's actually an alloy but it is largely made of cast iron. As you've probably experienced, iron rusts when exposed to moisture. Steel rotors rust even faster in the Canadian climate with salt on the roads.

Why rust isn't good for rotors

Rust weakens your rotors and lowers the brake pad performance, also contributing to the noise your brakes make when you're driving. Rust can make your disc rotor surface "pitted" or not smooth which can lead to uneven wear and a host of other issues.

My rotors aren't shiny and have rust on them, should I be worried?

Depending on the rust itself and on the condition of your vehicle, rusty rotors can either not be a concern at all or might indicate a larger problem. The good news first - if your car sits overnight, your rotors get light surface rust from the moisture. Then, next time you drive, this rust is cleaned off by engaging the brake pads. So if you hear some noise in the morning but it goes away, this is nothing to worry about.

Now the bad news - if your car sits for a long time, and the rust eats away at your rotor then its surface won't be smooth anymore which can impact your braking performance negatively. Also, some cheaper brake pads, especially the painted kind, develop rust pretty quickly which is no good either. That's why it's important to invest in quality parts for your vehicle. 

Coated Rotors

Standard OEM replacement and the default on many cars is a simple uncoated rotor where the entire disc is exposed to the elements all the time. However, there is another option - a premium coated rotor that has a special barrier protecting this part. Although the barrier does wear off on the stopping surface, it still extends the life of your rotor and provides protection from rust. If you do live in a Northern climate like Canada where salt is used on the roads, your coated rotors will deteriorate quicker. 

How to prevent rust on rotors

If you are working from home and don't really need your car, still take it out at least a couple of times a week to do groceries or to get a car wash. Car wash is actually a great way to maintain your vehicle because it cleans out any dirt that gets into places it shouldn't. With regular cleanings, you extend your vehicle's working life. Also, try to keep your car out of moisture, ideally in a garage or another indoor covered facility. This way, your vehicle is protected from the elements and is less likely to develop rust issues.