What Causes Rear Brake Lock-Up?
2 Answers
There are several reasons for rear wheel lock-up in vehicles: water ingress in the brake drum; hard emergency braking; or water entering the brake pads during car washing. Below are detailed explanations for each cause: Water ingress in the brake drum: If water is not promptly removed after driving in the rain or if the brake drum gets wet during car washing and is left untreated, rust can form on the brake drum, eliminating the gap between the drum and the brake shoes, leading to wheel lock-up. Replacing the brake pads can resolve this issue. Hard emergency braking: If the brake pedal is pressed too hard, the brake shoes can lock the wheels. Installing an ABS (Anti-lock Braking System) can prevent wheel lock-up during braking. Water entering the brake pads during car washing: When the driver washes the car with the handbrake engaged, water can enter the rear wheels, causing the brake pads and brake drum to lock together, resulting in rear wheel lock-up. If the brake pads and drum stick together after water ingress, gently tapping the brake drum with wood or a hammer can free the locked wheel.
I think the issue of rear brake locking is mainly caused by rust or seizing of the pistons in the brake calipers, which causes the brake pads to stick tightly to the disc. Common causes include prolonged exposure to moisture or dust, and deteriorated or contaminated brake fluid can also affect the operation of the hydraulic system, while blocked pipelines only make matters worse. In my years of experience, this problem is more likely to occur during rainy seasons in cities. For prevention, I recommend cleaning the brake system every six months and checking if the calipers slide smoothly—don’t wait until the tires are worn out to address it. From a safety perspective, brake locking can slow down the vehicle, increase fuel consumption, and may even lead to uneven braking force, potentially causing accidents. If you notice abnormal noises or the wheel rims heating up, you should pull over and inspect them immediately.
