Chevrolet Corvette 1963 Repair & Tune-Up Manual page 283

1. Thumbscrew
2. Vent cover
3. Flat washer
4. Reservoir cover
5. Gasket
6. Body
7. Valve seat
8. Valve assembly
9. Spring
10. Primary cup
11. Secondary cup and piston
12. Lockring
Exploded view of 1963-64 master cylinder
OVERHAUL
NOTE: Overhaul of the main cylinder por-
tion of power brake master cylinders is the
same as that for manual master cylinders.
1. Secure the master cylinder in a vise and
remove the push rod assembly and the pro
tective boot. This exposes the lock ring which,
when removed, allows extraction of the pis
ton stop, secondary cup, and piston.
2. Remove the cylinder end plug and
push out the primary cup, spring, valve as
sembly, and seat.
3. Wash the component parts with clean
alcohol only, and be sure that all traces of
gasoline or kerosene are removed. Gasoline
will cause premature deterioration of the cyl
inder's rubber parts.
4. Carefully inspect the washed metal
parts and the cylinder bore. A corroded cyl
inder must be replaced. Discoloration or
stains should be removed with crocus cloth.
When doing so, wrap the cloth around a fin
ger and rotate the cylinder around the sup
ported cloth. Do not polish the bore length
wise as this can cause a fluid leak.
5. Check the piston-to-cylinder clear
ance with a: feeler gauge. Clearance should
be between 0.001 in. and 0.005 in.
6. To reassemble, moisten the cylinder
bore with clean brake fluid and replace the
valve seat, valve assembly, and spring.
NOTE: Be sure that the valve and seat are
properly installed before proceeding. An
incorrectly assembled check valve will dis-
tort and fail to provide a check valve seal,
which will result in a reduction of brake
pedal travel and a corresponding loss of ac-
tual braking.
7. Moisten the primary cup with clean
brake fluid and install it, flat side out, and
seated over the spring. The primary cup is
distinguished by a brass support ring at its
base.
8. Dip the secondary cup in clean brake
fluid and slip it over the end of the piston.
9. Insert the completed assembly, with
the bleeder brake end of the piston installed
first. Secure the parts with the piston stop
and the snap-ring, and install the end plug.
10. Attach the rubber boot and push rod,
and replace the cylinder on the firewall.
11. Attach the brake pedal clevis and ad
just the push rod-to-piston clearance. Cor
rect adjustment calls for a barely perceptible
free pedal before piston/push rod contact.
Master Cylinder—Disc Brakes
1967-82
The early disc brake master cylinder is ser-
viced in the same manner as the drum brake
master cylinder. The later master cylinder is
the dual reservoir type. This offers a separate
brake circuit for the front and rear wheel pairs
and prevents total loss of braking should one
circuit fail.
This master cylinder is actually two com-
plete master cylinders contained in a single
housing, with the front reservoir controlling
the front brake pairs and the rear reservoir,
the rear brake line just below the master cyl-
inder.
Be absolutely certain that replacement
parts are identified as identical to those being
PRIMARY SEAL
SEAL PROTECTOR
LOW PRESSURE
SECONDARY SEAL
HIGH PRESSURE
SECONDARY SEAL
RETAINER RING
-PRIMARY PISTON
Exploded view of 1967-82 master cylinder
BRAKES 263
SECONDARY PISTON
BAIL