Singletracks contributor Sam James mentioned another important piece of this equation that’s often misunderstood. A lot of folks think that they need to lube the pistons in order to maintain proper movement and pad engagement, but in fact, you want to do the opposite. The pistons will slide inward to adjust for pad wear without the help of additional lube, and adding lubrication between the piston and the seal can actually cause problems. If the surfaces between the position and seal are too slick, the piston will slide around in the seal instead of the seal flexing as it’s designed, resulting in a piston and pad that doesn’t retract properly. This is one of the many ways you can end up with rubbing brake pads. The piston needs the flex and retraction of that quad-ring seal in order to come back to its intended resting place. So, when you rebuild calipers it’s often a good idea to clean and reinstall the seals and pistons before any oil is introduced into the system.