DIY Brake Caliper Replacement

When removing and replacing a brake caliper from a car's wheel, the removal process can vary depending on the make and model. Consulting an automotive repair guide for your model is highly recommended, and leaving the work to a professional is even better.

Removing the Old Caliper

The wheel must be disconnected from the vehicle to reach the caliper. Raise the vehicle on a higher-quality jack stand than its stock jack if possible, then use the "five-star" pattern to remove the lug nuts, disconnecting the nut opposite from the one you previously removed. Disconnecting the brake hose from the caliper first will help prevent it from getting damaged. Loosening the banjo bolt that holds it in place will require a socket wrench. Because brake fluid will come out of the hose once it's disconnected, you need a drip pan ready; the fluid is highly toxic to animals. Let the fluid drip continuously into the pan, which means you need to properly dispose of it and add new fluid. However, if you have rubber plugs, plug the hose to keep excess fluid from pouring out.

Some calipers are mounted on with bolts that use a standard socket, but others use bolts that require a hex socket. Once you remove the bolts, it still may take some wiggling and effort to remove the caliper from the disc. With the caliper removed, check the brake pads to see if they (and subsequently the ones on the other wheel) need to be changed soon.

Installing the New Caliper

Before installing the new caliper, make sure its piston is compressed. A large C-clamp can be used to compress it, but you may also need a block of wood in between the clamp and piston depending on the piston's size. Fit the caliper in place on its mounting bracket and install the bolts; it helps to lubricate the bolts with high-temperature grease first. Connect the hose onto the caliper -- removing any plugs from the hose first -- with the banjo bolt. Don't reconnect the wheel just yet.

Bleeding the System

Disconnecting the brake hose brought air into the brake system, so you need to bleed it. You need a second person to help you bleed the air out of the brake system. Having the brake system filled with fluid is vital, so top off the master cylinder and reservoir with brake fluid. If you only disconnected the brake hose at one caliper and the brake fluid was not excessively low, you should only need to bleed at this one caliper.

Attach a clear tube to the bleeder valve on the caliper and place the tube's other end into a container of fluid; a disposable plastic bottle will do. Open the caliper's bleeder screw as your assistant presses down on the brake pedal and look for air bubbles in the tube and container. When the fluid is running out of the tube cleanly, close the valve, remove the hose and replace the wheel. If you let the brake fluid drain out through the brake hose while changing the caliper, you may need to repeat this procedure at the other three wheels.