2. Unscrew the brake line from the caliper. It is connected by a hollow bolt with two copper washers. The washers should always be replaced. Plug the hole in the caliper so that no fluid can escape. Also put some tape around the hose connection to prevent dirt from getting into the hose.
3. Loosen both caliper bolts on the inside.
4. Remove the caliper. The caliper can be removed together with the brake pads, which are then removed as described above. If the brake disc needs to be removed, it can be unscrewed from the hub. The caliper can be disassembled as follows, using the illustration:
Internal parts of the caliper cylinder
1 - cylinder gasket; 2 - dust protection ring; 3 - caliper piston
5. Unscrew the brake hose from the caliper.
6. Carefully remove the dust ring from the cylinder bore using a screwdriver.
7. Now you need to squeeze the piston out of the caliper hole. Compressed air is used for this. It is best to take the caliper to a gas station to squeeze the piston out. The air duct is connected to the brake hose pipe in the place shown in the illustration. Place a wooden block in the caliper grip so that the piston cannot hit the metal of the cylinder.
Blowing out the piston from the caliper cylinder.
8. Remove the piston gasket from the cylinder groove with a blunt object.
(The article was copied from here: NissanBook)
9. Check the inside of the cylinder for scoring or other damage. If any, the entire cylinder should be replaced. Light irregularities can be smoothed with fine sandpaper. The piston sliding surface is specially treated and cannot be sanded with sandpaper. The piston gasket and dust ring should be replaced.
10. If both guide pins or their associated seals are unsatisfactory in appearance, they can be replaced. Lubricate the new pins with brake grease.
11. When assembling, coat all internal parts with brake fluid or special grease and then assemble the caliper as follows:
12. Insert the gasket into the cylinder groove.
13. Lubricate the dust ring with grease or brake fluid and install it on the piston.
14. Insert the piston into the bore and press the dust ring into the groove of the cylinder. The piston should be facing outward with the direction indicated on the illustrations side.
15. Lubricate both guide pins with recommended disc brake grease, install the seals and insert both pins.
16. Install the caliper in the reverse order of removal. Tighten the bolts as shown in illustrations torques for the corresponding execution. If the caliper holder was unscrewed, tighten the bolts with a force of 72 - 97 N·m. Bleed the brake system (Section Bleeding the brakes).