Genuine BMW 34117845133 Brake Caliper; Front Left – BMW

Brake calipers are the hydraulic clamps that create the friction needed to slow and stop BMW models equipped with disc brakes. They function by using hydraulic fluid to force pistons inside the caliper to press brake pads on both sides of the brake rotor. The friction created by the brake pads pressing against the rotor slows the rotation of the rotor until it eventually stops turning. Every time you press on the brake pedal, hydraulic fluid is sent to the brake calipers for them to engage the pads.

Brake calipers are machined parts and are designed for the life of your BMW. However, they do have seals and boots that can wear out and moisture can cause the calipers, caliper pistons, and brake bleeder screws to rust.

Replacing Your BMW Brake Calipers

• Replacing brake calipers requires the caliper to be disconnected from the brake hydraulic line and unbolted from the steering knuckle or wheel spindle.
• Before bolting on a new brake caliper, it should be fitted with new brake pads and the brake rotor should be replaced.
• Once the new brake caliper is bolted on the steering knuckle or wheel spindle and the brake hydraulic line is reconnected, the brake caliper and other calipers on the vehicle must be bled to remove all air from the brake hydraulic system.
• The brake calipers can be bled by pumping the brake pedal and holding it pressed then loosening the bleeder screw on the caliper.
• Once the bleeder screw is loosened, air will be forced out of the caliper being replaced by brake fluid and the brake pedal will drop to the floor.
• Before releasing the brake pedal the bleeder screw must be tightened to prevent air from entering back into the caliper when the pedal is released.
• This process must be repeated until no air comes out of the caliper and then repeated for each caliper to remove all air from the brake hydraulic system.

BMW Brake Calipers.