Drive through deep snow or park in a storm and snow and ice can pack into the wheels and around the brakes. Usually harmless, it can occasionally cause dragging, noise, or a frozen brake. Here is what to know about snow-packed brakes.
Why snow packs into the brakes
Slush and snow thrown up by the tires collect in the wheel wells and around the calipers and rotors, then freeze - especially after the warm brakes melt snow that refreezes as ice when you park. In deep snow, packed ice can wedge between the pad and rotor or against the dust shield.
Common effects
Packed snow and ice can cause a temporary scraping or grinding noise, a dragging feel, or a vibration until it clears. A bent or ice-jammed dust shield can scrape the rotor. Most of this clears within a few stops as braking heat and friction melt and knock the ice loose.
The frozen parking brake risk
The bigger winter issue is the parking brake freezing on from packed snow and moisture - see parking brake frozen in winter. In heavy snow many drivers skip the parking brake and leave the car in Park or in gear instead, to avoid a frozen brake in the morning.
What to do
Let braking heat clear light packed snow - a few gentle stops usually does it. For a frozen brake, free it gently as covered in the winter guide, and keep up general winter brake care. Keep the rear brakes healthy with quality pads and hardware.