The braking performance of Passenger Car Brake Pads depends on the friction coefficient of composite friction materials. Temperature changes directly alter the physical properties of these materials. Therefore, ambient temperature does influence brake feel and performance.
At low ambient temperatures, such as on cold winter mornings after vehicle startup, the friction material stays cold and rigid. Molecular activity decreases and the friction coefficient temporarily declines. When pressing the brake pedal, drivers may notice soft initial pedal response with delayed build-up of braking force. This is normal. After driving a few kilometers, repeated braking warms up the pads; the friction material returns to its normal state and brake feel stabilizes. In extremely cold conditions, thin frost or moisture may form on pad and rotor surfaces, further reducing friction for a short time.
In hot summer weather, combined with frequent stop-and-go braking in urban traffic, brake pads quickly reach high operating temperatures. Once pad temperature exceeds its working range, brake fade occurs. Drivers will feel a firmer pedal, reduced braking power, longer stopping distances and inconsistent linear delivery of braking force. This brake fade becomes more pronounced after multiple heavy consecutive stops.
Alternating hot and cold conditions induce thermal expansion and contraction in both brake pads and rotors. The friction layer and metal backing plate of brake pads have different thermal expansion coefficients. Rapid temperature changes slightly deform the pads, altering contact conformity between pads and rotors. Drivers may experience momentary wandering feel or slight pedal judder during braking. It is important to distinguish ambient air temperature from heat generated by braking itself. Heat produced by repeated heavy braking exerts a larger impact on brake pad performance than ambient temperature alone. During daily driving, avoid aggressive hard braking when the brake system is still cold. Wait until braking components warm up before normal operation to reduce stress on the brake system.
