What Causes Car Brake Lock-Up?
2 Answers
Reasons for car brake lock-up: For cars without ABS, if the brake pedal is pressed too hard while driving, the wheel speed will drop rapidly. When the braking force exceeds the friction between the wheels and the ground, the wheels will lock up. Fully locked wheels can lead to some dangerous situations. If the front wheels lock up, the vehicle will lose steering ability because the front wheels are the steering wheels. In this case, the vehicle will slide forward due to inertia, which can easily cause accidents. If the rear wheels lock up, the vehicle may skid sideways, which is extremely dangerous, especially on rainy or snowy roads. To avoid brake lock-up, try to avoid emergency braking. Anticipate potential hazards in advance and brake early. Brake before turning to reduce speed, not during the turn, as this can prevent wheel lock-up.
That day, I was driving long-distance when the brakes suddenly locked up, almost causing a rear-end collision. It wasn’t until I took it to the repair shop that I understood the reason. Common issues include rusted and stuck brake caliper pistons, especially when parked for long periods in humid areas. Another problem is dirty or water-contaminated brake fluid, which can boil under high temperatures, creating vapor lock and insufficient system pressure, causing the wheels to lock. If neglected, lack of lubrication in the brake caliper guide pins can also lead to sticking. The scariest scenario is not drying the brakes promptly after driving through water and then parking on a slope with the handbrake engaged, which makes lock-up more likely. I’ve learned to lightly press the brakes after rain to remove moisture, regularly change the brake fluid, and maintain the guide pins. It’s been six years without any recurrence.
