I would take the pistons out and clean the bores.
See Figures 5 through 18
Fig. Fig. 5: Unfasten the nut...
Fig. Fig. 6: ... then remove the lever
Fig. Fig. 7: Remove the lever seal and...
Fig. Fig. 8: ... the anti-friction washer, if used
Fig. Fig. 9: Rotate the actuator screw...
Fig. Fig. 10: ... then remove the piston from the bore
Fig. Fig. 11: Remove the balance spring
Fig. Fig. 12: Remove the actuator screw by pressing on the thread end
Fig. Fig. 13: Remove the shaft seal and thrust washer from the screw
Fig. Fig. 14: Remove the boot, being careful not to scratch the caliper bore
Fig. Fig. 15: Use ring pliers to compress the retainer...
Fig. Fig. 16: ... then withdraw the retainer from the bore
Fig. Fig. 17: Remove the piston locator...
Fig. Fig. 18: ... then remove the piston seal from the caliper bore
- Remove the caliper assembly from the vehicle as previously outlined.
- Remove the sleeve and bolt boots. Check the boots and bolts for damage and corrosion.
- Remove the brake pad retainer from the end of the piston by rotating the retainer until the inside tabs line up with the notches in the piston.
- Remove the locknut, lever, lever seal and anti-friction washer (if installed) from the caliper.
- Remove the piston by using a wrench to rotate the actuator screw to work the piston out of the caliper bore.
- Remove the balance spring and actuator screw.
- Remove the shaft seal, thrust washer and boot.
- Remove the retainer using ring pliers and a piston locator.
- Remove the piston seal using a non-metallic seal pick.
- Carefully remove the bleeder valve. If the valve breaks, the caliper should be replaced.
- Inspect all parts for damage and replace if necessary.
- Clean all parts in denatured alcohol and dry with compressed air.
- Install the bleeder valve.
- Install the bracket and bolt.
- Lubricate the new piston seals with clean brake fluid and install into the caliper bore. Make sure they are not twisted.
- Lubricate the piston locating tool J36627, do NOT install the piston.
- Install the thrust washer on the actuator screw with the copper side towards the piston.
- Lubricate the shaft seal and install it on the actuator screw.
- Install the actuator into the piston assembly.
- Install the balance spring and retainer into the piston.
- After all the components are lubricated and installed into the piston, install the piston into the bore. Push the piston into the bore so that the locator is past the retainer groove in the caliper bore.
- Install the retainer using retainer ring pliers.
- Install the boot onto the piston with the inside lip of the boot in the piston groove and the boot fold is towards the end of the piston. Push the piston to the bottom of the bore.
- Lubricate and install the lever seal over the end of the actuator screw.
- Install the lever and rotate away from the stop slightly. Hold the lever while tightening the locknut to 32 ft. lbs. (44 Nm).
- Install the pad retainer in the groove at the end of the piston.
- Align the inside retainer tabs with the piston notches. Rotate the retainer so that the tabs enter the piston groove.
- Lubricate with silicone grease and install the sleeve and bolt boots.
- Install the caliper assembly and tighten the retaining bolts to 92 ft. lbs. (125 Nm).
- Bleed the brake system as outlined in this section.