Caliper Disassembly

WARNING: Under no condition should air pressure ever be used to remove a piston from a caliper bore. Personal injury could result from such a practice.

Remove caliper from brake rotor. Hang assembly on a wire hook away from rotor, so hydraulic fluid cannot get on rotor. Place a small piece of wood between piston and caliper fingers. Carefully depress brake pedal to hydraulically push piston out of bore. Then apply and hold down brake pedal to any position beyond first inch of pedal travel. This will prevent loss of brake fluid from master cylinder.
If both front caliper pistons are to be removed, disconnect brake tube at flexible brake hose at frame rail. Plug brake tube and remove piston from opposite caliper using same process as above for first piston removal. Disconnect brake fluid flex hose from caliper assembly.
CAUTION: DO NOT use excessive force when clamping caliper in vise. Excessive vise pressure will cause bore distortion and binding of piston.
To disassemble caliper, mount in a vise equipped with protective jaws. Remove guide pin sleeves and guide pin bushings. Remove piston dust boot from caliper and discard. See Figure . Using a soft tool, such as a plastic trim stick, work piston seal out of its groove in caliper piston bore, See Figure . Discard old seal. DO NOT use a screw driver or other metal tool for this operation, because of possibility of scratching piston bore or burring edges of seal groove.
Clean all parts using alcohol or a suitable solvent and wipe dry using only a lint free cloth. No lint residue can remain in caliper bore. Clean out all drilled passages and bores. Whenever a caliper has been disassembled, a new boot and seal must be installed at assembly. Inspect piston bore for scoring or pitting. Bores that show light scratches or corrosion can usually be cleared of light scratches or corrosion using crocus cloth. Bores that have deep scratches or scoring should be honed.
Use Caliper Hone (Special Tool C-4095), or equivalent providing diameter of bore is not increased more than .0254 mm (.001"). See Figure . If bore does not clean up within this specification, a new caliper housing should be installed. Install a new piston if old one is pitted or scored.
NOTE: When using Caliper Honing Tool (Special Tool C-095), coat stones and bore with brake fluid. After honing bore, carefully clean seal and boot grooves with a stiff non-metallic rotary brush.

NOTE: Use extreme care in cleaning caliper after honing. Remove all dirt and grit by flushing caliper with brake fluid; wipe dry with a clean, lint free cloth and then clean a second time.

CAUTION: When inspecting caliper piston, do not use anything but solvents to clean piston surface. If surface of piston cannot be cleaned using only solvents, piston must be replaced.
Inspect caliper piston for pitting, scratches, or any physical damage. Replace piston if there is evidence of scratches, pitting or physical damage.