Q:

What causes front brakes to lock up?

A:

The most common culprit of locked-up brakes is a malfunction in the master cylinder. The master cylinder is the primary operating system that produces mechanical force from the brake pedal to pistons that operate the drum brakes. The master cylinder system relies on seals leading to the brakes to maintain pressure so the brake system slides to a stop with ease.

When the seals in the master cylinder break down, the pistons in the system do not return properly, and the line pressure to the brake pads becomes uneven. This chain of events causes the brakes to overheat and lock up. If just one set of brakes locks up, the cause may lie within a caliper piston that is dragging, ultimately causing friction and overheating the brake fluid that then throws off the in-line pressure of that particular brake system.

While replacing the master cylinder is the most expensive repair to fix the brakes, vehicle owners can have a certified mechanic check to see if replacing individual calipers and rotors might provide a solution to brakes locking up before embarking on more major repairs. Routine brake maintenance and brake pad replacement also serves as a preventative measure to reduce the risk of locked-up brakes.


Is this answer helpful?

Similar Questions

  • Q:

    Why do car brakes lock up?

    A:

    While there are several reasons brakes lock up, one is a dragging caliper piston. The friction this causes heats brake fluid and increases the pressure in the brake lines, locking a single wheel. Taking the car for a short drive and then checking the wheels for one that is warmer than the rest is a quick way to check for this problem.

    Full Answer >
    Filed Under:
  • Q:

    What are the common causes of pulsating car brakes?

    A:

    The common causes of pulsating car brakes can include the Antibrake System (ABS), a poorly installed wheel or a warped rotor. In fact, pulsating car brakes is a common complaint regarding ABS brakes when the ABS system kicks in. This usually happens when braking on ice, wet roads, or gravel.

    Full Answer >
    Filed Under:
  • Q:

    How do you gravity bleed your brakes?

    A:

    Gravity bleeding brakes involves attaching clear tubing to the vehicle's bleeders and manipulating the tubing to release trapped air bubbles in the braking system. The required supplies are an automotive jack, four jack stands, 1 quart of brake fluid, 5 feet of 3/16-inch tubing, an empty quart jar, a hammer, masking tape, vise grip pliers and an open-end wrench. This procedure takes about 30 minutes.

    Full Answer >
    Filed Under:
  • Q:

    Why do my brakes pulsate when stopping?

    A:

    An uneven rotor surface is the most common cause of pulsation that drivers feel in their brake pedal while braking. Tomorrow's Technician explains that the surface of brake rotors, sometimes called brake discs, should not vary any more than 0.001 inches around the entire rotor. This means that even the slightest variation in the surface of a rotor or disc is felt by drivers when braking.

    Full Answer >
    Filed Under:

Explore