 2006 Disc Rear Brakes
Replaced driver side rear rotor and pads on 5-24-08 @ 38,000 miles. Pads were 100% gone, but inner & outer were worn equally. Attempted to push piston in w/ "C" clamp -- mistake. Bought a 6-in-1 ( fits 6 different piston styles ) w/ 3/8 sq drive, from local NAPA parts dealer, $12.
Problem: piston would not screw in when turning (clockwise) w/ tool.
Cause: the screw threads ( inside the piston ) had come so far out of the female nut that they became burred and would not fit into the nut. Two possible causes of the burring 1. the pads were worn too small - or - 2. I caused the burrs when attempting to compress piston w/ clamp.
Solution: Used a very small fine tooth triangle file and removed the burrs on the end of the screw threads. The screw has 4 separate spiral threads. To remove the piston to access the screw had to disconnect the hydraulic hose @ the wheel well fitting, make sure piston is fully unscrewed using 6-in-1 tool ( counterclockwise rotation ) and blow piston out of the caliper cylinder using compressed air @ 90 psi ( cover w/ rag to catch hydraulic fluid. Reassembly of piston/caliper went smoothly. Bled lines w/ helper peddle pusher.
Questons: 1) Original rotors were Bosch brand, Ford dealer replacement was Motorcraft, not Bosch, and the hole on the rotor to install the flat head Torx socket fastener bolt that locked rotor to the axle hub was missing on Motorcraft replacement rotor. Dealer service Dept. said "not needed". True or not? Bosch rotor looked like possibly a higher quality design. Rotor centered and secure, possible movement of the rotor due to clearence for wheel stud bolts eliminated by Torx socket bolt.
2) The front brake pads still have about half of their lining material, yet rear pads are gone. Is this a 500 model trait to be expected, or did the emergency brake mechanism have something to do w/ lifespan of pads?
3) How does the emergency brake linkage inside the caliper piston actually work? | 
