Why Brake Disc Rust Happens and How to Prevent It

Imagine you're driving down the road, enjoying a smooth ride, when suddenly you hit the brakes, only to hear a loud, unsettling grinding noise. You may notice decreased braking performance, or unexpected vibrations. What you're experiencing is brake disc rust – a common issue that can affect the performance and safety of your vehicle. In this guide, we'll look at why brake disc rust happens, what can happen as a result, and most importantly, how you can prevent it from happening in the first place.

Understanding Brake Disc Rust

Rusting Brake Discs - MAT Foundry

Brake discs, also known as rotors, are critical components of your vehicle's braking system. They work in conjunction with brake pads to slow down or stop your car when you apply pressure to the brake pedal. Most brake discs are made of cast iron, which can rust when exposed to moisture and oxygen. Brake disc rust occurs when the surface of the disc oxidises due to environmental factors such as rain, snow, road salt, or even just humidity in the air.

The Consequences of Brake Disc Rust

While a little surface rust on your brake discs may seem harmless, it can have significant implications for your vehicle's performance and safety. Rust buildup on the surface of the discs can lead to uneven wear and tear, causing vibration and noise when braking. In severe cases, excessive rust can compromise the integrity of the brake discs, reducing their effectiveness and increasing stopping distances. Additionally, rust particles can contaminate the brake pads, leading to accelerated wear and diminished braking performance.

Common Causes of Brake Disc Rust

Several factors contribute to brake disc rust:

1. Moisture: Water is the primary catalyst for rust formation. Rain, snow, and road spray can all come into contact with your brake discs, initiating the rusting process.

2. Road Salt: In regions where road salt is used to melt ice and snow, the corrosive properties of salt can accelerate rust formation.

3. Humidity: High levels of humidity in the air can contribute to rust buildup on brake discs, especially if the vehicle is parked for extended periods without use.

4. Inactivity: Vehicles that sit idle for prolonged periods are more susceptible to brake disc rust, as the discs are not regularly exposed to friction, which can help prevent rust formation.

Preventive Measures to Combat Brake Disc Rust

Preventing Brake Disc Rust - MAT Foundry

Now that we understand why brake disc rust occurs, here are some preventive measures to keep your brake discs in top condition:

1. Regular Use: One of the most effective ways to prevent brake disc rust is by regularly using your vehicle. Frequent driving allows the brake discs to heat up and shed any surface rust that may have formed during periods of inactivity.

2. Keep Your Car Clean: Washing your car regularly helps remove dirt, grime, and road salt that can contribute to rust formation. Pay special attention to the wheels and brake components when cleaning your vehicle.

3. Avoid Parking in Wet Areas: Whenever possible, try to park your car in a dry, covered area to minimise exposure to moisture. If parking indoors is not an option, consider using a car cover to protect your vehicle from the elements.

4. Brake Gently After Driving Through Water: If you've driven through a puddle or encountered heavy rain, lightly tap the brake pedal a few times to remove any water from the surface of the brake discs.

5. Apply a Rust Inhibitor: There are several rust inhibitors and protective coatings available that can help prevent brake disc rust. These products create a barrier between the surface of the disc and environmental contaminants, reducing the risk of oxidation.

6. Perform Regular Maintenance: Routine maintenance is essential for preserving the integrity of your brake system. Inspect the brake discs, pads, and calipers regularly for signs of wear or corrosion, and address any issues promptly.


Brake disc rust is a common issue that can affect the performance and safety of your vehicle. Understanding the causes of brake disc rust and implementing preventive measures can help keep your brake system in optimal condition. By regularly using your vehicle, keeping it clean, avoiding parking in wet areas, and applying rust inhibitors, you can minimise the risk of brake disc rust and ensure smooth, reliable braking performance. Remember, a little maintenance goes a long way in preserving the integrity of your brake system and keeping you safe on the road.

Explore MAT Foundry's Step-by-Step Guide to Brake Disc Installation and Maintenance here.

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