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BRAKES 5-21
brake fluid. Coat the primary and secondary seals
on the secondary piston with clean brake fluid. Insert
the secondary piston spring retainer into the sec-
ondary piston spring. Place the retainer and spring
down over the end of the secondary piston until the
retainer locates inside of the lips of the primary
cup.
10. Hold the master cylinder with the open end of the
bore down. Push the secondary piston into the bore
until the spring seats against the closed end of the
bore.
11. Position the master cylinder in a vise with the
open end of the bore up. Coat the primary and
secondary seal on the primary piston with clean
brake fluid. Push the primary piston assembly,
spring end first, into the bore of the master cylinder*
Hold the piston down and snap the lock ring into
position in the small groove in the I.D. of the bore.
12. Push the primary piston down to move the secondary
piston forward far enough to clear the stop screw
hole in the bottom of the front fluid reservoir. Install
the stop screw.
13. Install reservoir diaphragm in the reservoir cover
and install the cover on the main cylinder. Push
bail wire into position to secure the reservoir cover.
Installation
1. Assemble the push rod through the push rod retainer,
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.
3. Secure .the main cylinder to the firewall with mount-
ing bolts.
4. Connect the push rod clevis to the brake pedal with
pin and retainer.
5. Connect the brake lines to the main cylinder.
6. Fill the main cylinder reservoirs to the levels
shown in Figure 8. Bleed the brake system as out-
lined in this section.
7. K necessary, adjust the brake pedal free play as
outlined in this section.
WHEEL CYLINDER (Fig. 33)
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.
Removal
1. Raise vehicle and place on jack stands.
Fig. 33-Chevelle Wheel Cylinder—Exploded View
1. Push Rod Boot
6. Spring
2. Piston
7. Piston Cup
3. Piston Cup
8. Piston
4. Housing
9. Push Rod Boot
5. Fluid Inlet
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.
NOTE: On Chevrolet, it is necessary to re-
move the anchor pin which holds the front wheel
cylinder to flange plate to remove the front
wheel cylinder.
Disassembly
1. Remove boots from cylinder ends with pliers and
discard boots.
2. Remove and discard pistons and cups.
Inspection and Cleaning
NOTE: Staining is not to be confused with
corrosion. Corrosion can be identified as pits
or excessive bore roughness.
1. Inspect cylinder bore. Check for staining and corro-
sion. Discard cylinder if corroded.
2. Polish any discolored or stained area with crocus
cloth by revolving the cylinder on the cloth sup-
ported by a finger. Do not slide tfce cloth in a
lengthwise manner under pressure.
NOTE:
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 Declene or
equivalent.
4. Shake 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. 33)
1. Lubricate the cylinder bore and counterbore with
clean
brake
fluid and insert spring - expander
assembly.
2. Install new cups with flat surfaces 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 Durex pistons into cylinder with flat
surfaces toward center of cylinder. Do not lubri-
cate pistons before installation.
4. Press new boots into cylinder counterbores by hand.
Do not lubricate boots prior to installation.
Installation
1. Position wheel cylinder to brake flange plate. Install
screws and tighten securely.
NOTE: On Chevrolet front wheels, mount front
wheel cylinders to the brake flange plate by
installing the threaded anchor pin through the
wheel cylinder housing and tighten to 130 lb. ft.
To secure, peen over the flat washer on the
anchor pin.
CHEVROLET CHASSIS SERVICE MANUAL
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