How does freezing weather affect car brakes?

Answer 1

Cold weather by itself doesn't affect braking much, provided the brake system is in good working order. Most brake pads do not grab efficiently until they get hot, ceramic pads especially, but the brakes get hot within seconds of application and remain plenty warm enough until the vehicle is parked - there is always light contact between the pads and rotors. However, moisture in the brake system can freeze and prevent application or cause the brakes to hang up and stay applied. Additionally, moisture in a brake system that is hot can boil and cause the brakes to fade badly once the vehicle has been driven a few miles. Brake fluid is hygroscopic, meaning it absorbs moisture, so the fluid should be flushed at the manufacturer's recommended interval to prevent these problems. (Keep in mind I am no longer a technician and have NOTHING to gain by telling people to get service....this really is a necessary procedure)

One other interesting note, on a snowy or wet day when the brakes are continually getting wet, the temperature of the rotors/drums is 20-30% higher than it is on a dry day. This is due to the water acting as a lubricant on the brake parts and the increased hydraulic force it takes to achieve enough friction to stop the vehicle. Drastic temperature fluctuations cause rotors to warp and will make the brake pedal pulsate on application. Keep this in mind when driving in poor conditions. Not only is it a good idea to stop more gently because of slippery road conditions, but it will also prolong brake life and help to prevent vibrations while braking.