Why do brake pads turn yellow?
3 Answers
Brake pads turning yellow is due to rust formation. The main performance characteristics of brake pads are as follows: 1. High performance: High friction coefficient (Golden Unicorn ceramic brake pads have a friction coefficient of 0.45, belonging to high-friction brake pads), heat resistance, outstanding performance during high-speed and high-temperature driving, with good braking effectiveness and comfort under high-speed and high-temperature conditions. 2. Safety: Low heat fade, excellent recovery performance, with no reduction in braking performance on mountainous roads or under high-temperature and high-speed conditions. Maximizes vehicle safety. Highly suitable for use in mountainous areas, highways, and various other road conditions. 3. Comfort: Comfortable braking, no noise, no pollution, and balanced braking. 4. Reasonable service life: For general non-modified vehicles under normal driving conditions, the lifespan of front brake pads is 30,000–50,000 kilometers, while rear brake pads last 80,000–100,000 kilometers. Front brake discs have a lifespan of 60,000–100,000 kilometers. Brake pads and discs of vehicles frequently driven in mountainous areas have a significantly shorter lifespan.
I also noticed my brake pads turning yellow when washing my car the other day. After checking some information, I learned this is normal. Brake pads contain metal components like iron and copper, which can oxidize and rust when exposed to humid air, causing the surface to turn yellow or brown. This is especially common after driving in the rain or washing the car. Sometimes, high temperatures during braking can also darken the surface color of the brake pads. However, this doesn't affect their performance. I checked my car's brake pads and confirmed they still have sufficient thickness, and there's no unusual noise when braking, so I didn't worry about it. Of course, if you also experience longer braking distances or squeaking sounds, it's best to get them checked.
Having repaired cars for over a decade, I've seen countless owners concerned about yellowing brake pads. It essentially boils down to three scenarios: First, material oxidation—the metal in brake pads rusts when exposed to water or moisture. Second, discoloration from high temperatures—like when emergency braking heats pads to hundreds of degrees, causing surface material to yellow. Third, contamination—such as dried mud or road grime. Honestly, this doesn't affect braking performance at all. As long as pads are over 5mm thick, drive worry-free. Coastal vehicle owners should take note though—prolonged dampness accelerates rusting, but a few brake applications will wear it off.
