Removing the square cut seal from the caliper bore is one of the first stages of brake caliper disassembly. Learn how to disassemble and clean brake calipers in this free auto repair video featuring a certified mechanic.
In this clip, we're going to talk about the proper service procedure to rebuild a front brake caliper. Now what I'm going to do is remove the square cut seal from the caliper bore. This is your square cut seal here. You're going to take and loop around it and fish it out. This is a very unique type of seal, only to brake calipers. Fits around just like so. Normally it would be a lip type seal, you would think like in a wheel cylinder, or a crank shaft seal, rear main seal, or a cam shaft seal. This doesn't have a particular lip on it. What happens is this seal actually rocks back and forth, as the caliper pushes out, it's going to rock backwards. The action of the seal rocking forward is what returns the caliper piston and releases the pressure holding your brakes apply. There are no return springs to deal with. What we're going to do is take a clean, lint-free rag and clean up our piston. This particular piston is ceramic. You want to be very careful with it. If you drop it, it will break. Some pistons are steel, and some are even plastic. Once we have it clean, we're going to sit it dirty side down, this is the side that exposed, right here. It's not necessary to hone a caliper bore unless it is extremely degraded. If yours is extremely degraded, I would suggest just purchasing a new caliper. The reason for that is the seal does not slide along inside the bore. The seal sits inside this groove, and the piston rides on the seal, so there's no honing necessary. We take and clean it out with a lint-free rag, just making sure to get all the large contaminants out of it. And there you go. That is the proper service procedure for disassembling and cleaning your brake caliper.