Why does brake failure occur when brake pads overheat?

[LeElijah]

High temperatures can cause vaporization of brake fluid. Below is relevant information about brake pads: 1. Classification of brake pads: Asbestos brake pads (mostly phased out), semi-metallic brake pads, low-metallic brake pads, NAO formula brake pads, ceramic brake pads, NAO ceramic brake pads. 2. Ceramic brake pads vs traditional brake pads: In traditional brake pads, metal is the primary material generating friction, providing strong braking force but with significant wear and prone to noise. After installing ceramic brake pads, abnormal squealing (clicking sounds) won't occur during normal driving. Since ceramic brake pads contain no metal components, they avoid the metallic screeching noise caused by friction between traditional metal brake pads and their counterparts (i.e., brake pads and rotors). 3. Stable friction coefficient: Ordinary brake pads use immature friction materials, and excessively high friction coefficients can lead to loss of directional control during braking, pad burning, rotor scratching, and other safety hazards. Even when brake rotor temperatures reach 650°C, ceramic brake pads maintain a friction coefficient between 0.45-0.55, ensuring excellent braking performance.

[LaTimothy]

When I was driving downhill on a mountain road before, continuous braking caused the brake pads to overheat, resulting in a noticeable decrease in braking power. This happens because the heat generated by friction between the brake pads accumulates too quickly. When the temperature gets too high, the material on the surface of the pads softens or chars, significantly reducing the friction coefficient. Normally, the vehicle slows down through contact between the pads and the disc, but when overheated, it's like ice skates losing grip on ice—braking force drops sharply. Additionally, high temperatures can cause a steam layer to form near the brake pads, separating the friction zone and further weakening braking effectiveness. This situation is common during long downhill drives or with heavy vehicles, so it's important to use lower gears for engine braking or stop to let the brakes cool down early on. Safety comes first—I've learned this the hard way. Now, I always check brake pad wear in advance and keep cooling vents clear to avoid losing control in emergencies.

[WestonLynn]

As a mechanic with years of experience working with cars, I've found that brake failure caused by overheating pads is primarily a physical issue. Normal friction generates significant heat, but when temperatures spike, the friction material degrades and the surface becomes smoother, reducing grip effectiveness. More seriously, heat can cause localized boiling of the brake fluid, creating air bubbles that lead to hydraulic system failure and a spongy pedal feel. This thermal fade is particularly common in racing or during long-distance driving. I recommend regularly checking pad thickness, using high-quality materials, and avoiding prolonged continuous braking—such as using engine braking downhill or taking breaks to cool down. These practices extend component lifespan, significantly reduce accident risks, and aren't troublesome to maintain—they just require more attention to driving habits.

[VanDamian]

I'm fascinated by automotive principles. The science behind brake pad overheating failure is quite simple: high temperatures alter the material structure. Normal braking relies on friction for deceleration, but excessive heat buildup can cause the resin in brake pads to carbonize or metal components to deform, leading to a sharp drop in friction coefficient. Additionally, high temperatures may cause air expansion between discs and pads, forming an air cushion that reduces contact surface area and slows brake response. This is common in heavy-load driving or racing scenarios. For prevention, I usually plan routes to avoid sudden braking on steep slopes, upgrade to high-performance heat dissipation pads, or ensure proper fluid circuit function. Understanding these principles helps avoid reckless modifications and ensures safe, smooth travels every time.