How Does a Brake Caliper Work?

A brake caliper is designed to utilize brake fluid under pressure to transfer force the brake pads. In-turn the brake pads contact the rotating brake rotor to slow the car. A brake caliper is typically mounted to the spindle or backing plate. There are two basic designs of brake caliper mounting, fixed and floating. A fixed position brake caliper is bolted to the spindle and is not allowed to move. This kind of brake caliper is constructed with caliper pistons on both sides of the caliper. The floating style of caliper is mounted to the spindle or backing plate using a slide bolt. This slide bolt design allows the caliper to slide on these bolts. This design uses pistons on just one side of the brake caliper.

Fixed Mount Brake Caliper
Brake calipers can have from 1 to 6 pistons depending on manufacturer design. All brake calipers are fitted with a brake fluid bleeder. This bleeder is designed to allow air to escape from the system. If air is allowed in the system it can cause brake operation failure. A brake caliper piston is sealed to the brake caliper housing using a main piston seal. This seal allows the piston to move back and forth without allowing brake fluid to leak. This seal is protected by a dust seal that keeps debris from contaminating the integrity of the seal. The brake system should always be flushed and bled regularly to prevent moisture from creating rust. This rust can cause the caliper piston seal to fail allowing brake fluid to leak. If your brake caliper is leaking you must replace the caliper or rebuild the caliper using a brake caliper rebuild kit.

Floating Brake Caliper
This kit replaces the main seal and dust guard. A high pressure brake hose is connected from the car frame or body to the caliper. This hose is sealed against the brake caliper using a copper sealing washer. When removing this hose it is recommended that a new copper sealing washer is installed. Anytime the brake system is opened a brake system bleed is necessary.




Exploded Brake Caliper (Floating)
Replacing a Brake Caliper:

• Loosen but (Do Not Remove) the lug nuts of the wheel to be serviced
• Support car in a safe position high enough to remove the brake caliper
• Remove the lug nuts and wheel
• Loosen the hydraulic brake hose at the caliper, do not remove
• Loosen appropriate nuts and bolts to remove the caliper
• Continue the remove the hydraulic brake hose
• Clean all caliper slides and mounting surfaces, lubricate as needed
• Reconnect hydraulic brake hose
• Re-Install new or rebuilt brake caliper
• Tighten all mounting bolts with the brake hose fitting
• Bleed brake system as needed
• Slowly push the brake pedal down and then up to take up air gap space between the brake pad and rotor
• Inspect brake caliper and hose connection for leaks, if brake fluid leaks exist repair as needed
• Reinstall wheel and lug nuts, lower the tire onto the ground then finish tightening lug nuts
• NEVER MOVE A CAR WITHOUT NORMAL BRAKE PEDAL OPERATION

Rebuilding a Brake Caliper:

• Once the brake caliper has been removed the caliper piston will need to be removed this can be done either with a pry bar on either side to work the piston out of the housing or inserting compressed air into the hydraulic hose fitting. If compressed air is used use caution because the piston will shoot out the caliper housing with force. Install shop towels in between the piston and caliper housing and keep fingers away from the piston.
• When the brake caliper is apart clean all debris and rust from all components. If severe rust exists replacement is required
• Install new seal with a touch of brake fluid for lubricant and insert the brake caliper piston into the main caliper housing
• Now install the new dust boot over the piston and into the main housing
• Reinstall caliper to bleed and recheck as needed
• Slowly push the brake pedal down and then up to take up air gap space between the brake pad and rotor
• Inspect brake caliper and hose connection for leaks, if brake fluid leaks exist repair as needed
• Reinstall wheel and lug nuts, lower the tire onto the ground then finish tightening lug nuts
• NEVER MOVE A CAR WITHOUT NORMAL BRAKE PEDAL OPERATION