Re: 164 Rear Brake Caliper
You need to "screw" the piston back into the calliper. Inside the piston there's a screw thread and ratchet mechanism that mechanically pushes the piston out every time the handbrake is pulled on but doesn't go fully back when it is released. This takes up the wear in the pads. The best way (unless you have a proper calliper wind-back tool) that I've found is to put a G clamp on the piston to apply a small amount of pressure back into the housing and then at the same time, twist the top of the piston with something like a pair of water pump pliers in such a way as to "screw" it bacj into it's housing. You'll need to keep tightening up the G clamp as it moves back, but obviously, if you do it up too tight, it will be hard to turn the piston.