After replacing a brake caliper, a common question is whether you need to bleed the brakes. The answer is yes - opening the caliper lets air into the system. Here is what to know about bleeding after a caliper job.
Why you must bleed
Removing a caliper opens the hydraulic line, so air gets in. Air compresses where fluid does not, giving a soft, spongy pedal until it is removed; see caliper diagnosis. Bleeding pushes the air out and restores a firm pedal.
Bleed at least that corner
At minimum, bleed the corner you opened. Many techs bleed working from the caliper furthest from the master cylinder inward, or bleed all four if the fluid was low or old. Keep the reservoir topped so you do not draw in more air.
How to bleed
Use the two-person pump-and-hold method, a one-person bottle or vacuum method, or a pressure bleeder; see one-person bleeding. Open the bleeder, push fluid through until it runs clear with no bubbles, then close it. Watch the reservoir level throughout.
Finish right
Pump the pedal firm before driving, check for leaks at the caliper fittings, and top off the fluid. Replace the pads and service the rotor on that corner too. Fit quality pads and hardware.