Kelsey-Hayes Double Pin Caliper
DISASSEMBLING CALIPER1. Support caliper assembly on upper control arms on shop towels to absorb any hydraulic fluid loss.
2. Place a small piece of wood between the piston and caliper fingers.
3. Carefully depress brake pedal to hydraulically push piston out of bore (brake pedal will fall away when piston has passed bore opening).
4. Prop brake pedal to any position below the first inch of pedal travel -- to prevent loss of brake fluid.
If both front caliper pistons are to be removed:
1. Disconnect flexible brake line at frame bracket after removing piston.
2. Plug brake tube and remove piston from opposite caliper.
WARNING: Under no condition should air pressure be used to remove piston from bore! Personal Injury could result from such practice.
3. Disconnect brake flexible hose from the caliper.
4. To disassemble, mount caliper assembly in a vise equipped with protective jaws.
CAUTION: Excessive vise pressure will cause bore distortion and binding of piston.
Fig. 10 Dust Boot Removal:
5. Support caliper and remove dust boot and discard.
Removing Piston Seal From Caliper:
6. Using a plastic trim stick, work piston seal out of its groove in piston bore. Discard old seal. Do not use a screwdriver or other metal tool for this operation, because of possibility of scratching piston bore or burring edges of seal groove.
Bushing and Sleeve Assembly Service
NOTE: The bushing and sleeve assembly is a sealed for life unit. To service this unit:
Removing Inner Sleeve From Bushing:
a. Push out and then pull the inner sleeve from the inside of the bushing using your fingers as shown.
Removing Bushing From Caliper:
b. Using your fingers collapse one side of the bushing while pulling on the opposite side to remove the bushing from the caliper assembly.
CLEANING AND INSPECTION
Clean all parts using alcohol or a suitable solvent and blow dry, using compressed air. Blow out all drilled passages and bores.
NOTE: Whenever a caliper has been disassembled, a new boot and seal must be installed at reassembly.
Honing Brake Caliper Piston Bore:
Inspect the piston bore for scoring or pitting
- Bores that show light scratches or corrosion, can usually be cleared with crocus cloth.
- Bores that have deep scratches or scoring should be honed, providing the diameter of the bore is not increased more than 0.0254 mm (0.001 inch).
- If the bore does not clean up within this specification, a new caliper housing should be installed. Install a new piston if the old one is pitted or scored.
When using a hone:
Coat the stones and bore with brake fluid. After honing the bore, carefully clean the seal and boot grooves with a stiff nonmetallic rotary brush.
Use extreme care in cleaning the caliper after honing. Remove all dirt and grit by flushing the caliper with brake fluid; wipe dry with a clean, lintless cloth and then clean a second time.
ASSEMBLING CALIPER
1. Clamp caliper in vise with protector jaws.
CAUTION: Excessive vise pressure will cause bore distortion and binding of piston.
Installing New Piston Seal In Caliper:
2. Dip new piston seal in clean brake fluid and install in groove in bore. Seal should be positioned at one area in groove and gently worked around the groove, using fingers until properly seated.
CAUTION: NEVER USE AN OLD PISTON SEAL. (Be sure that fingers are clean and seal is not twisted or rolled).
3. Coat new piston boot with clean brake fluid leaving a generous amount inside of boot.
4. Position dust boot over piston after coating with brake fluid.
Fig. 4 Caliper piston installation:
5. Install piston into bore pushing it past the piston seal until it bottoms in the bore.
CAUTION: Force must be applied uniformly to avoid cocking and binding of the piston in the caliper bore.
6. Position dust boot in counterbore. Using a hammer and Tool C4842 with C4171 handle or equivalent, drive boot into counterbore.
Fig 16 Installing Bushings:
Guide Pin Sleeve Bushing Installation
a. Fold the bushing in half lengthwise at the solid middle section of the bushing.
Removing Bushing From Caliper:
b. Using your fingers insert the folded bushing into the caliper assembly. Making sure the solid section of the bushing is fully seated into the bushing hole of the caliper assembly. Do not use a sharp object to perform this step due to possible damage to the bushing.
c. Unfold the bushing using your fingers or wooden dowel until the bushing is fully seated into the caliper assembly with the flanges seated evenly on both sides of the bushing holes in the caliper assembly.
Fig 7 Installing Caliper Sleeves:
Guide Pin Sleeve Installation
a. Install the sleeve into one end of the bushing until the seal area of the bushing is past the seal groove in the sleeve.
b. Holding the convoluted end of the bushing with one hand. Push the sleeve through the bushing until the one end of the bushing is fully seaated into the seal groove on the one end of the sleeve.
c. Holding the sleeve in place work the other end of the bushing over the end of the sleeve and into the seal groove. Be sure the other end of the bushing did not come out of the seal groove in the sleeve.
NOTE: Before installing caliper assembly on vehicle, inspect braking disc for runout, thickness, and thickness variation.
7. Install caliper assembly.
8. Install brake hose to caliper using new seal washers.
9. Bleed the brake system.