Disassembly (Piston & Seal)
WARNING:
Under no condition should high pressure air ever be used to remove a piston from a caliper bore. Personal injury could result from such a practice.
NOTE:
Before disassembling the brake caliper, clean and inspect it.
NOTE:
The safest way to remove the piston from the caliper bore is to use the hydraulic pressure of the vehicle's brake system.
- After removing disc brake shoes, remove the caliper from the brake rotor and hang the assembly on a wire hook away from rotor and body of the vehicle so brake fluid cannot get on these components.
- Mount the caliper in a vise equipped with protective jaws.
- Place a wooden block in caliper. See Fig 1 . Block should be sized to allow piston to push out of bore far enough to be removed by hand after being loosened by air pressure, yet large enough to keep piston from coming completely out utilizing air pressure.
- Apply low pressure compressed air to caliper fluid inlet in short spurts to ease piston out of bore.
- Remove piston from caliper.
- Remove the piston dust boot from the caliper and discard. See Fig 2 .
- Using a soft tool such as a plastic trim stick, work the piston seal out of its groove in caliper piston bore. See Fig 3 . Discard the old seal.
- Inspect the piston bore for scoring or pitting. Bores that show light scratches or corrosion can usually be repaired using crocus cloth.
CAUTION:
Do not use excessive force when clamping caliper in vise. Excessive vise pressure will cause bore distortion.
NOTE:
Do not use a screwdriver or other metal tool for seal removal. Using such tools can scratch the bore or leave burrs on the seal groove edges.