Chevrolet 1977 light duty truck, Service Manual

Page: 418 / 861

Remove the piston by directing compressed air into
the caliper inlet hole (fig. 5-36).
CAUTION: Use ju s t enough air pressure to ease
the piston out o f the bore. I f the piston is blown
out, even with p adding provided ' it m ay become
damaged.
4. Use a screwdriver to pry the boot out o f the
caliper. Extend the screwdriver across the caliper bore,
u nder the boot, an d pry up. Be careful not to scratch the
caliper bore.
5. Use a piece o f wood or plastic — a plastic
toothpick is ideal — to remove the piston seal from its
groove in the caliper bore. D O N O T USE A M ETA L
T O O L O F A N Y T Y PE F O R THIS O PE R A T IO N .
6. Remove the bleeder valve from the cliper.
C leaning and Inspection
1. T h e boot, piston seal, ru b b er bushings and
sleeves are to be replaced each time the caliper is
overhauled. Discard, do not bother to clean and inspect,
these parts.
2. C lean all other parts in clean d en atu red alcohol
or brake cleaner. Use dry, filtered compressed air to dry
p arts and blow out all passages in the caliper and
bleeder valves.
The use o f lubricated shop air will leave a film o f
m in e ra l oil on the metal parts. This m ay d am ag e
ru b b e r parts w hen they come in contact after
reassembly.
3. Check the m o u n tin g for corrosion, breaks in the
p latin g o r other dam ag e. Do not use abrasives in an
atte m p t to clean the pins -- replace them.
4. C arefully exam ine the piston outside d iam eter
for scoring, nicks, corrosion an d worn or dam ag ed
c h ro m e plating. If any surface defects are detected,
replace the piston.
5. Check the bore in the caliper for the same
defects as the piston with the exception o f plating
dam ag e. T h e piston bore is not plated and stains or
m in o r corrosion can be polished with crocus cloth. Do
not use em ery cloth. Thoroughly clean the caliper after
the use o f crocus cloth. If the bore cannot be cleaned up
in this m anner, replace the caliper.
R eassem bly
1. Lubricate the bore in the caliper and the new
piston seal with clean brake fluid. Position the seal in the
caliper bore groove. Lubricate the piston with clean
b rak e fluid and assemble a new boot into the groove in
the piston so that the fold faces the open end o f the
piston. Insert the piston into the caliper bore, using care
not to unseat the seal and force down to the bottom in
the bore. This will require a force o f 50 to 100 pounds.
Position the outside d ia m e te r o f the boot in the caliper
counterbore and seat with Tool J-22904 (fig. 5-37).
2. Check the boot installation to make sure that
the retaining ring molded into the boot is not bent and
th at the boot is installed fully, below the caliper face,
and evenly all around. Otherwise dirt or moisture may
enter the bore and cause d am ag e or corrosion.
Fig. 5 -37-S eating Boot
3. Install the brake hose in the caliper inlet using a
new copper gasket.
Installation
1. Installation o f the caliper and m ounting parts
(rub b er bushing, sleeves, shoe and lining assemblies and
pins) is the same as for lining replacem ent except for the
following:
a. T he brake hose must be connected to the
brake pipe at the fra m e or fram e bracket.
Use extreme care to orient the hose so that the
keyed hose end fitting aligns with the slot in the
bracket without twisting or kinking the hose.
b. A fter overhaul — or any time that the brake
hose or line is disconnected — the calipers must be bled.
Bendix
Removal
CAUTION: Clean dirt fr o m hose to caliper
connection before proceeding with removal.
1. Remove the hose to caliper bolt and cap or tape
the open connections to prevent dirt from entering the
hose or caliper. Discard the copper gaskets.
2. Remove the caliper assembly as described under
"S hoe and Linings-Removal".
Disassembly (Fig. 5-38)
1. Clean the exterior o f the caliper using clean
brake fluid and place on a clean work surface.