How to Clean Brake Calipersby Jody L. Campbell
There was a day when calipers were rebuilt by mechanics and labor charges were applied to the customer in order to do so. Now, remanufacturing companies rebuild calipers, which has brought the price of calipers down significantly. In many cases, if a caliper piston is seized, it is more financially smart to replace the caliper then it is to pay the technician to rebuild it. Calipers have many lubrication points, and often, the fingers of the pads' backing plates can seize against the metal housing of the calipers. Calipers should be serviced and cleaned at every brake pad replacement or when they fail due to lack of lubrication.
Put on the breathing mask and safety glasses. Lift the vehicle to waist level. Remove the hubcap(s). Remove the lug nuts or studs with the impact gun and socket. Remove the wheel.
Place a caliper hose crimp on the brake hose snugly. Place a drain pan beneath the wheel and then remove the banjo bolt of the brake hose from the caliper. Some brake fluid will drain into the pan, but the crimp will help with brake fluid loss if placed securely enough on the brake hose.
Disassemble the caliper from the wheel. Remove the two caliper bolts using a ratchet and socket or compatible hand wrench. Certain calipers may combine the caliper bolt as the caliper slide. This style will have a long, smooth shaft and be threaded on the end where it screws into the caliper bridge. Other types of calipers use smaller threaded bolts and the slides are separate components. Set the bolts or bolts/slides aside.
Pry the caliper off of the rotor with a pry bar. Place the caliper into the drain pan so the position of the brake hose connection is low so the brake fluid will drain from it. Some style calipers will have the brake pads clipped to them while others leave the pads behind in the caliper bridge. For pads that are clipped onto the calipers, remove the pads prior to placing the caliper into the drain pan.
Use an impact gun and a socket to remove the two caliper bridge bolts from the knuckle. Remove the pads if applicable. Remove the pads' rattle clip hardware from the caliper bridge if applicable. This hardware clip should be replaced for extreme caliper services where the pads were stuck/seized in the bridge. It will take less time and offer the pads a new, smooth surface to move against.
Clean the surface of the caliper where the hardware was just removed from (in the absence of rattle clips, clean the pads contact points of the caliper) using a die grinder with a coarse reconditioning disc until the surface of the area is smooth and clean. This removes rust and corrosion buildup.
Apply a light coat of antiseize lubricant or silicone based brake lubricant to the area of the bridge cleaned with the die grinder. Install the new brake hardware rattle clips (if applicable) and then apply another light coat of lubricant on the entire surface of the clips. Set the bridge aside.
Bring the drain pan and caliper to the bench vise. Place the pan beneath the bench vise and place the caliper into the vise. Compress the caliper piston(s) using a caliper piston tool. The remaining brake fluid will purge from the brake hose banjo bolt hose and into the drain pan. Reposition the rubber boots of the pistons if necessary. If the boots are torn, they should be replaced (see References) or if the pistons are not allowing you to compress them, the caliper should be replaced.
Remove the protective caliper slide rubber boots from the caliper. These boots should also be replaced if cracks or tears are present on them. Caliper hardware kits sometimes include new slide boots and if this is the case, replace them regardless. Spray brake cleaner into the slide cavity holes. Use a caliper honing tool to the caliper slide cavities to clean out brake dust, rust, and other corrosion buildup.
Return to the caliper slides and bring them to the bench grinder. Clean the smooth surface of the slides on the wire brush wheel thoroughly until smooth and shiny.
Replace the protective rubber boot slides onto the caliper. Apply a liberal coat of antiseize lubricant or silicone based brake lubricant to the caliper slides. In applications that combine the slide and bolt, do not place the lubricant on the threads of the bolt and set them aside. In applications that use separate slides and bolts, insert the slides into the caliper and make sure they move smoothly back and forth.
Replace the caliper bridge and bolts. Torque the bolts to specifications required for the vehicle with the torque wrench and a socket. Replace the pads in the bridge if applicable.
Place the caliper over the pads and rotor. In applications where the pads clip to the caliper, install the pads first; inboard pad into the caliper piston bore, and then the outboard pad.
Replace the caliper bolts and tighten to torque specifications for the vehicle.
Replace the brake hose and the banjo bolt. It is recommended to replace the copper washers on both sides of the banjo bolt. Tighten the bolt according to torque specifications for the vehicle. Remove the brake hose crimp. Repeat steps 2-15 for the other caliper(s). Bleed the brake system when complete.
Replace the wheel(s), lug nuts or studs, and hubcap(s). Be sure to torque the lug nuts or studs to proper specifications for the vehicle. Lower the vehicle and test drive.