Chevrolet Light Duty Truck 1973, Service Manual

Page: 293 / 979

BRAKES 5 -2 7
surface of shoe rim and file off any burrs or high
spots.
2. Use released brake lining (or equivalent) and the
rivets included in lining package which are of the
correct size. The rivets must fit the holes with the
solid body of rivet extending through the shoe rim,
but no farther.
CAUTION:
Keep hands clean while handling
brake lining. Do not permit oil or grease to
come in contact with lining.
3. Start riveting at center of shoe and lining and work
toward the ends. Use a roll set for reveting; a star
set might split the tubular end and then the rivet
would not fill the hole. The primary lining is shorter
than secondary lining, therefore, the rivet holes at
each end of the shoe rim are not used.
4. After riveting is completed, lining must seat snugly
against shoe with no more than .005" separation
midway between rivets. Check with a .004" (Go)
and a .006 (No Go) feeler gauge.
ANCHOR PIN REPLACEMENT
Removal
1. Raise vehicle on a hoist.
2. Remove wheel and drum as outlined in this section.
3. Remove brake shoe pull back springs, link and
guide plate.
4. Disengage anchor pin lock and remove pin from
flange plate (Threaded type).
Installation
1. Position anchor pin to flange plate, install lock
washer and torque pin. Lock by peening over
washer tabs.
CAUTION:
See Caution on Page 1 of this
section.
2. Install brake shoe guide plate, link and pull back
springs.
3. Adjust brakes, install drum and wheel as outlined
previously in this section.
4. Lower vehicle and test brake operation.
WHEEL CYLINDER
CAUTION:
Always use clean brake fluid to
clean wheel cylinder 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 extremely short
time.
The wheel cylinder boots should be removed from a
cylinder body only when they are visibly damaged or
leaking fluid. Wheel cylinders having torn, cut, or heat-
cracked boots should be completely overhauled.
Wheel Cylinder Repair
Wheel cylinders should not be disassembled unless they
are leaking or unless new cups and boots are to be
installed. It is not necessary to remove the wheel cylinder
from the flange plate to disassemble, inspect, and
overhaul the cylinder. Removal is necessary only when
the cylinder is damaged or scored beyond repair.
Removal
1. Place vehicle on hoist.
2. Remove wheel and tire assembly. Back off brake
adjustment, if necessary, and remove drum.
3. Disconnect brake system hydraulic line from
cylinder.
4. Remove brake shoe pull back springs.
5. Remove screws securing wheel cylinder to flange
plate. Disengage cylinder push rods from brake
shoes and remove cylinder.
Disassembly (Fig.
52)
1. Remove boots from cylinder ends.
2. Remove pistons and cups.
Inspection and Cleaning
NOTE: Staining is not to be confused with
corrosion. Corrosion can be identified with
pits or excessive bore roughness.
1. Inspect cylinder bore. Check for staining and
corrosion. Discard cylinder if corroded.
2. Polish any discolored or stained area with crocus
cloth by revolving the cylinder on the cloth
supported by a finger. Do not slide the cloth in a
lengthwise manner under pressure.
CAUTION:
Before washing parts, hands must
be clean. Do not wash hands in gasoline or oil
before cleaning parts. Use soap and water to
clean hands.
3. Wash the cylinder and metal parts in clean brake
fluid.
4. Remove excess cleaning fluid from the cylinder. Do
not use a rag to dry the cylinder as lint from the
rag cannot be kept from the cylinder bore surfaces.
5. Check piston for scratches or other visual damage;
replace if necessary.
Assembly (Fig.
52)
1. Lubricate the cylinder bore with clean brake fluid
and insert spring-expander assembly.
2. Install new cups with flat surface toward outer ends
of cylinder. Be sure cups are lint and dirt free
before insertion. Do not lubricate cups prior to
assembly.
LIGHT DUTY TRUCK SERVICE MANUAL