GMC 1976 ZEO 6083 Maintenance Manual page 248

CLEANING AND INSPECTION
The boot, piston seal, rubber bushings and
sleeves are to be replaced each time the caliper is
overhauled .
Clean all other parts in clean Declene or equiva-
lent . Use dry, filtered compressed air to dry parts and
blow out all passages in the caliper and bleeder valve.
WARNING : THE USE OF LUBRICATED SHOP
AIR WILL LEAVE A FILM OF MINERAL OIL ON
THE METAL PARTS . THIS MAY DAMAGE RUB-
BER PARTS WHEN THEY COME IN CONTACT
AFTER REASSEMBLY.
Check the mounting bolts for corrosion, breaks
in the plating or other damage . Do not use abrasives
in an attempt to clean the bolts. If bolts are damaged,
replace them .
Carefully examine the piston OD for scoring,
nicks, corrosion and worn or damaged chrome plat-
ing. If any surface defects are detected, replace the
piston .
NOTE :
The piston OD is the primary sealing
surface in the caliper assembly . It is manufac-
tured and plated to close tolerances . Refinishing
by any means or the use of any abrasive is not
acceptable .
Check the bore in the caliper for the same defects
as the piston . The piston bore is not plated and stains
or minor corrosion can be polished with crocus
cloth . Do not use emery cloth or any other form of
abrasive . Thoroughly clean the caliper after the use
of crocus cloth . If the bore can not be cleaned up in
this manner, replace the caliper.
ASSEMBLY
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 brake fluid and assemble a new boot into the
groove in the piston so that the fold faces the open
end of 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
of 50 to 100 pounds .
Position the OD of the boot in the caliper coun-
terbore and seat with Tool J-22904 (figure 35).
Check the boot installation to make sure that the
retaining ring molded into the boot is not bent and
that the boot is installed fully-below the caliper face
-and evenly all around . Otherwise dirt or moisture
may enter the bore and cause damage or corrosion.
Figure 35-Boot Installation
1 . Scribe front and rear housing.
Figure 36-Separating Halves
BRAKES
5- 29
Install the brake hose in the caliper inlet using a
NEW copper gasket .
POWER BRAKE BOOSTER
OVERHAUL
DISASSEMBLY
CAUTION :
Care must be used in handling
the diaphragm of power piston assembly.
Guard diaphragm against grease, oil, for-
eign matter and nicks or cuts.