The Signs & Symptoms of a Stuck Caliper

In automotive disk brake systems, pressing the brake pedal generates hydraulic pressure in the brake lines and actuates a piston in a caliper at each wheel. The piston pushes the disk brake pads into contact with the brake rotor, stopping the vehicle. A common malfunction in disk brakes is a stuck piston in the wheel caliper. Inserting a caliper spreader between the brake pads to press the piston back into the caliper can release a frozen caliper piston. A new caliper or an overhaul of the existing caliper is required to prevent recurrence. Symptoms of a stuck caliper are definitive and hard to miss; ignoring them can be unsafe and expensive.

Severe Steering

A caliper piston can stick in the closed position. When this happens the brake shoes operated by that caliper are constantly applied, causing an imbalance of braking force when the brake pedal is pushed and brakes are applied to the other wheels. The vehicle pulls strongly toward the side with the stuck caliper. It's often necessary to steer against this pulling tendency, sometimes forcefully, in order to keep the vehicle moving in a straight line while applying the brakes.

Mileage Variances

Driving with one brake always "on" significantly reduces acceleration. The car will feel sluggish and less responsive. Fuel efficiency and gas mileage may decline sharply.

Something's Burning

A stuck caliper inflicts considerable friction on the brake pads. You'll probably smell the pungent odor of brake linings being seared by heat from constant contact with the brake rotor. If you put your hand against the wheel with the stuck caliper immediately after driving, the wheel may feel hot to the touch. Still more friction-related drama, including smoke and/or boiling brake fluid, may occur if you drive with a severely stuck caliper at freeway speeds.

Shakes and Shudders

A stuck caliper often wears the brake rotor unevenly, creating high and low spots. Brake pads passing over the uneven surface of the rotor may cause wheel shudder or vibration. This is transmitted into the steering system and may be misdiagnosed as a wheel alignment problem or worn steering linkage.

High Maintenance

You'll find yourself shelling out more money for brake repairs, and with greater frequency, if you're driving around with a sticky caliper piston. Brake lining life expectancy is severely reduced by a frozen caliper and a new pair of disk brake pads can be eaten up in a very short time. Because wear is accelerated, the pads may wear down to the rivets unexpectedly fast. The rivets then score the surface of the brake rotors, leading to still additional repair expense.