Main Cylinder; Wheel Cylinder Repair; Wheel Cylinder - Explode - Chevrolet 10 1971 Series Chassis Service Manual

BRAKES 5-16
PUSH R O D A N D BO O T
CUP RETURN SPR IN G WITH E X PA N D E R S
W HEEL CYLINDER H O U S IN G
PISTO N CUP
PUSH R O D A N D BO O T
Fig. 35— Wheel Cylinder - Explode
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 in­
stalled. It is not necessary to remove the brake cylinder
from the backing plate to disassemble, inspect, and over­
haul the cylinder. Removal is necessary only when the
cylinder is damaged or scored beyond repair.
Removal for Overhaul
1. Place car 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. 35)
1. Remove boots from cylinder ends.
2. Remove pistons and cups.
Inspection and Cleaning
Staining is not to be confused with cor­
NOTE:
rosion. Corrosion can be identified with pits or
excessive bore roughness.
1. Inspect cylinder bore. Check for staining and cor­
rosion. 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.
Before washing parts, hands must be clean.
NOTE:
Do not wash hands in gasoline or oil before clean­
ing parts. Use soap and water to clean hands.
3. Wash the cylinder and metal parts in denatured alcohol.
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.
PISTO N
PIST O N CUP
BLEEDER SC R EW
5. Check piston for scratches or other visual damage;
replace if necessary.
Assembly (Fig. 35)
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.
3. Install new pistons into cylinder with flat surfaces
toward center of cylinder. Do not lubricate pistons
before installation.
4. Press new boots onto cylinder by hand. Do not lubri­
cate boots prior to installation.
Installation
1. Position wheel cylinder to brake flange plate. Install
screws and tighten securely.
All brake attachements are important
NOTE:
attaching parts in that they could affect the
performance of vital components and systems,
and/or could result in major repair expense.
They must be replaced with parts of the same
part numbers or with equivalent parts if re­
placement becomes necessary. Do not use re­
placement parts of lesser quality or substitute
design. Torque values must be used as specified
during reassembly to assure proper retention
of these parts.
2. Install all push rods and pull back springs.
3. Connect hose or line to wheel cylinder.
4. Install all parts removed for accessability and
remove vehicle from hoist.
M A IN CYLINDER
Always use denatured alcohol or brake
NOTE:
fluid to clean any main cylinder or wheel cylin­
der parts.
Never use mineral-base cleaning sol­
CAUTION:
vent such as gasoline, kerosene, carbon-tetra-
chloride, acetone, paint thinner or units of like
nature as these solvents deteriorate rubber parts,
nature as these solvents deteriorate rubber
causing them to become soft and swollen in an
extremely short time.
Removal
1. Wipe main cylinder and lines clean with a clean
cloth. Place dry cloths below main cylinder area
to absorb any fluid spillage.
2. Disconnect hydraulic lines at main cylinder. Cover
line ends with clean lint-free material to prevent
foreign matter from entering the system.
3. Disconnect the push rod from the brake pedal.
4. Unbolt and remove the main cylinder from the
firewall (or power brake booster).
Installation
1. Assemble the push rod through the push rod re­
tainer, if it has been disassembled.
2. Push the retainer over the end of the main cylinder.
Assemble new boot over push rod and press it
down over the push rod retainer. Slide new mounting
gasket into position. Secure the main cylinder to
the firewall with mounting bolts.
This cylinder to dash fastener is an impor­
NOTE:
tant attaching part in that it could affect the per­
formance of vital components and systems, and/or
10-30 CHEVROLET TRUCK SERVICE MANUAL