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Summary
  • It’s normal for brake discs and rotors to develop rust, but too much of it can affect your vehicle’s braking performance.
  • Too much rust on the calipers can also cause them to stick and create drag.
  • Replacing rusty brake discs is a part of proper brake maintenance. Keeping your braking system in check helps with road safety and reduces repair costs associated with brake parts.

The overall condition of your vehicle’s braking system plays a significant role in ensuring your safety on the road. The system consists of several individual components that are crucial to its operation.

Most brake components are made from tough and durable metals, such as steel and cast iron. These materials enable parts like the brake discs and calipers to last for a long time before they need to be replaced.

However, when exposed to unfavorable conditions, metal components may become vulnerable to rust and corrosion.

Where’s the Rust?

Brake rotors on vehicles that are driven regularly won’t rust. If a regularly driven vehicle has any rusty rotors, it usually indicates a problem with a disc caliper or perhaps a proportioning valve, if one or more rear rotors are rusty on a vehicle that is driven often.

Vehicles that are parked for a few weeks will develop rusty rotor braking surfaces, and with that rust, there will be brake noise until the rust wears off.

, Rusty Brake Discs: Should You Be Worried?

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: In some cases, if a vehicle drove through a puddle right before being parked for a few weeks (think airport), some of the water can get trapped between the pads and the rotor and make a single rusty patch that will cause a strange feel during stopping that is sort of similar to a brake pulsation.

The other brake components are going to have some rust by default, particularly in cold northern states where the roads are salted in the winter.

worn out car backing plate and park brake shoe
This is not a disc rotor, but a backing plate. The brake rotor has been removed for replacement.. Notice the completely worn out park brake shoe right behind the wheel hub. This car came from New York and was brought in to have work done. The entire car had this same kind of damage. In addition to what you see here, all the brake lines had to be replaced on this vehicle. | Image Source: Richard McCuistian.

Are Rusty Brake Discs a Problem?

While doing your regular brake maintenance check, you start to notice rust on some of your brake components. What should you do?

Rusting in some parts of the vehicle’s braking system is normal. However, if you notice extensive rusting in the brake discs and calipers, they may need replacement.

Rust on Brake Discs

It’s common for brake discs (or rotors) to rust. For instance, the surface of these discs may be covered with a thin film of rust if you leave your vehicle parked outside during heavy snowfall or rain.

Rust that only exists on the surface of the brake discs is no cause for alarm. Surface-level rust usually goes away on its own once you drive your vehicle and use your brakes.

However, it’s a different story if you notice extensive rusting on your brake discs. This may affect your vehicle’s braking performance. For instance, accumulated rust on your discs can reach your brake pads, causing them to wear out faster.

Replace severely rusted brake discs right away to prevent such issues.

Worn-out brake discs and pads may also significantly affect the efficiency of your disc brake system. You may notice grinding noise coming from your wheels once your brake discs and pads have become severely rusted. More commonly, that kind of noise comes from pads that have given up all their lining so that the metal pad backing is grinding into the rotor.

Rust on Calipers

Aside from severely rusty brake discs, another brake component that’s vulnerable to rust is the brake caliper. Are rusty brake calipers a problem? Yes, they are, so don’t disregard extensive rust in your calipers. Of course, nobody usually looks at calipers unless they’re doing the brakes anyway – and steel calipers frames will rust unless they’re painted, even if nothing is wrong with them. That being said, if the rust is in the wrong places and is bad enough to prevent the caliper from working right, well, that’s a problem.

While minor surface rust is not a problem, excessive rust on your caliper’s slides, bushings, and pins may prevent a “floating” caliper from centering itself over the rotors. Because of this, your pads may wear out unevenly and cause unreliable braking.

Keep an eye out for rusty brake calipers during your regular maintenance intervals.

Severe rusting will cause a floating caliper to stick, which can then cause your brake pads to drag. That’s because the caliper may not allow enough movement for the brakes to be released.

Many vehicle manufacturers still use steel caliper pistons, which are plated with nickel and chrome to achieve the desired surface finish. Unlike phenolic caliper pistons (which are natural thermal insulators), steel pistons may transfer heat from the brake pads to the brake fluid.

The surface finish of these pistons plays a big role in how effectively it functions.

Since these pistons are made of steel, it’s sometimes unavoidable for the material to rust.

Any surface pitting may cause the piston to stick, affecting the efficiency of your brake system.

How Important is Brake Maintenance?

Here are some of the benefits of proper brake maintenance:

Improves the Efficiency of Your Braking System

Replacing severely rusted brake components will ensure that your brakes are in optimal condition. It also enhances stopping ability.

Helps with Road Safety

A properly functioning brake system will help you avoid road accidents. If you’re confident that your system is well-maintained, you can focus more on the road, resulting in a safer and hassle-free driving experience.

Reduces Future Repair Costs

Severely rusted brake discs and/or calipers may damage nearby brake components as well. Following your vehicle’s regular brake maintenance schedule will help you save more in the long run, as it’ll prevent issues in multiple brake components.

How Does a Disc Brake System Work?

To take care of your braking components properly, it helps to understand how the system works as a whole.

Each wheel has its own brake mechanism and hydraulic device. All four wheels are connected to your brake pedal.

A typical disc brake mechanism consists of a brake disc, a brake pad, and a brake caliper. Once you put pressure on your brake pedal, hydraulic fluid flows from the master cylinder to the brake caliper. The latter then squeezes the brake pads against the brake disc, creating the friction needed to slow down your wheels.

Most modern vehicles rely on disc brakes, but there are some that still use drum brakes for their rear wheels or emergency brakes.

Since all braking components are vital to the operation of your vehicle, any severely rusted component should be replaced right away.

What is a Brake Disc and Caliper Kit and When Do You Need It?

If your vehicle’s brake disc and calipers are severely rusted, it may be time to get a brake disc and caliper kit replacement. This kit is usually sold in a 2-wheel or 4-wheel set.

A brake disc and caliper kit usually costs around $250 to $1000, depending on the brand and the components included inside the kit. There are many aftermarket brands that sell high-quality brake disc and caliper kits, so you will surely find an excellent one for your vehicle.

What to Consider When Buying a Brake Disc and Caliper Kit

Due to the surplus of brake disc and caliper kits on the market, it may be difficult to pick the best one for your vehicle. Consider the following factors to narrow down your options:

Application

To guarantee fit, always check the kit’s compatibility with your ride. There are many aftermarket brands that sell model-specific brake disc and caliper kits, so you will surely find one for your vehicle.

brake disc little rust
To guarantee fit, always check the kit’s compatibility with your ride.

Cost

High-quality brake disc and caliper kits do not necessarily have to be expensive.

There are many replacement kits that can match the quality of their original equipment manufacturer (OEM) counterparts at reasonable prices.

You don’t have to break the bank just to buy one for your vehicle.

Brand

When buying brake components, choose the brand you trust the most. If you don’t have a brand preference, we recommend reading product reviews online or seeking professional advice from a mechanic.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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