Caliper O Ver H A U L - Chevrolet CHEVY VAN G10 SERIES Service Manual

CALIPER O VER H A U L

C A U T IO N : Always use denatured alcohol or brake
fluid to clean any caliper parts. Never use mineral-
base cleaning solvents such as gasoline, kerosene,
carbon-tetrachloride, acetone, paint thinner or units
of like nature as these solvents deteriorate rubber
parts, causing them to become soft and swollen in
an extrem ely short tim e.
Removal
1. D isconnect the hose from the steel brake line an d cap or
tape the fittings to prevent dirt from entering the line or
hoses.
2. Remove the U-shaped retainer from the hose fitting.
3. W ithdraw the hose from the fram e support bracket and
remove the caliper w ith the hose attached. Remove the
brake shoes from the caliper.
Disassembly
1. Clean the exterior o f the caliper using denatured alcohol
or equivalent and place on a clean w ork surface.
2. Remove the brake hose from the caliper and discard the
copper gasket. C heck the hose for w orn spots, cracks or
other signs o f deterioration. Discard the hose, if dam ­
aged, and replace w ith a new hose.
3. Drain the brake fluid from the caliper.
W A R N IN G : DO N O T PLA C E T H E F IN G E R S IN
F R O N T O F T H E P IS TO N IN A N A T T E M P T TO
C A TC H O R P R O T E C T
C O M PRESSED A IR .
4. Using clean shop tow els, pad the interior o f the caliper
and remove the piston by directing com pressed air in to
the caliper inlet hole (Fig. 37).
Fig. 3 7 —R em o ving P iston F ro m C aliper
IT W H E N A P P L Y IN G
C A U T IO N : Use just enough air pressure to ease
the piston out o f the bore. Do not blow piston out
of the bore.
N O T E : A nother method o f removing the piston is
to stroke the brake pedal (gently) w hile the hy­
draulic lines are still connected. This w ill push the
piston out o f the caliper bore.
5. Using a screwdriver and caution so as n o t to scratch the
piston bore, pry the dust b oot out o f the caliper piston
bore.
6
. Using a small piece o f w ood or plastic remove the piston
seal from its groove in the caliper piston bore.
C A U T IO N : Do not use a metal tool of any kind
fo r this operation.
7. Remove the bleeder valve from the caliper.
Cleaning and Inspection
N O T E : The dust boot, piston seal, rubber bushings
and sleeves are to be replaced each tim e that the
caliper is overhauled. Discard these parts — do not
bother to clean and inspect them .
1. Clean all parts (o th er th an those m entioned above) in
denatured alcohol. Use dry, filtered, com pressed air to
dry parts and blow o ut all passages in the caliper and
bleeder valve.
C A U T IO N : The use of lubricated shop air will
leave a film of mineral oil on the metal parts. This
may damage rubber parts when they come in con­
tact after reassembly.
2. Check the m ounting bolts for corrosion or other damage.
Do n ot attem p t to clean up the bolts. I f th ey appear
corroded — replace them .
3. Carefully exam ine the outside surface o f the piston for
scoring, nicks, corrosion an d worn or dam aged chrom e
plating. I f any surface defects are d etected, replace the
piston.
C A U T IO N : The piston
primary sealing surface in the caliper assembly. It is
manufactured and plated to close tolerances. Re­
finishing by any means or the use o f any abrasive is
not an acceptable practice.
4. Check the bore in the caliper for the same defects as the
piston. The piston bore, however, is not plated and stains
or m inor corrosion can be polished with crocus cloth.
C A U T IO N : Do not use emery cloth or any other
form of abrasive. Thoroughly clean the caliper after
the use of crocus cloth. If the bore cannot be
cleaned up in this manner, replace the caliper.
Reassembly
1. Lubricate the caliper piston bore and the new piston seal
BRAKES 5-19
outside diameter is the
C H E V Y V A N S H O P M A N U A L