Brake piston won't fully retract

[BDHoneyman]

I have the 11.65" rear brakes from Factory Five. For one of the brakes the piston is protruding about 1/8" from the fully-retracted position. As a consequence, when the brake pads are in place, the gap between the pads is too narrow for the brake to fit over the rotor. I can move the piston out using the emergency brake mechanism but it always returns to the slightly protruding position. I've tried pushing the piston back with my hand but no luck. Should I try more force by using a clamp or is there something else going on?

Thanks,
-Bruce

[jlfernan]

The rear calipers need a special tool to screw the piston in. The tool is simple and available at most auto parts store.

[Gordon Levy]

https://www.youtube.com/watch?v=rlMU8K36Hjo

[BDHoneyman]

Thank you!!
I told my wife that I need another tool and she laughed and said, 'Of course!
-Bruce