Chevrolet Light Duty Truck 1973 Service Manual page 295

difference between these 4 readings must not exceed
.006.
Cleaning
New brake drums are given a light coating of rust
proofing oil to prevent the formation of rust on the
critical braking surfaces during the time that the drums
are in storage.
This rust proofing oil must be carefully removed before
the drum is placed in service to prevent any of this oil
from getting on the brake shoe facings.
It is recommended that a suitable volatile, non-toxic,
greaseless type solvent be used to clean the oil from the
braking surface of the new brake drums before they are
placed in service to insure the cleanest possible surface.
Gasoline or kerosene should not be used as there is
danger that a portion of the diluted oil substance may be
left on the braking surface.
NOTE: All brake drums have a maximum
diameter cast into them. This diameter is the
maximum wear diameter and not a refinish
diameter. Do not refinish a brake drum that
will not meet the specifications as shown
below after refinishing.
ORIGINAL MAXIMUM REFINISH
DIAMETER DIAMETER
11.000 11.060
12.000 12.060
13.000 13.060
SHOE AND LININGS—FRONT DISC BRAKE
The brake linings should be inspected any time that the
Fig. 53-Measuring Drum Diameter
wheels are removed. Check both ends of the outboard
shoe by looking in at each end of the caliper. This is the
point at which the highest rate of wear normally occurs.
At the same time, check the lining thickness on the
inboard shoe by looking down through the inspection
hole in the top of the caliper--See "Brake Inspection".
The outboard shoes have ears near the outer edge which
are bent over at right angles to the shoe. The top ends of
the shoe have looped ears with holes in them which the
caliper retaining bolts fit through. The large tab at the
bottom of the shoe is bent over at a right angle and fits
in the cut-out in the outboard section of the caliper.
The inboard shoe and lining has ears on the top ends
which fit over the caliper retaining bolts. A special spring
inside the hollow piston supports the bottom edge of the
inboard shoe.
Removal
1. Remove master cylinder cover and observe brake
fluid level in front reservoir. If reservoir is more
than 1/3 full, siphon the necessary amount out to
bring the level to 1/3 full; this step is taken to
avoid reservoir overflow when the caliper piston is
REPLACEMENT
pushed back into its bore.) Discard the brake fluid
(DISCARD)
removed. Never reuse brake fluid.
DIAMETER
2. Raise the vehicle and remove the front wheels.
11.090
12.090
3. Push the piston back into its bore. This can be
13.090
accomplished by using a "C" clamp as shown in
Figure 54,
4. Remove the two mounting bolts which attach the
caliper to the support (fig. 55).
5. Lift the caliper off the disc.
. Remove the inboard shoe. Dislodge the outboard
6
shoe and position the caliper on the front
suspension arm so that the brake hose will not
support the weight of the caliper.
7. Remove the shoe support spring from the piston.
. Remove the two sleeves from the inboard ears of
8
the caliper.
9. Remove the four rubber bushings from the grooves
in each of the caliper ears.
Cleaning and Inspection
1. Thoroughly clean the holes and the bushing grooves
NOTE: Outboard shoes (with formed ears)
are designed for original installation only
and are fitted to the caliper. The shoes should
never be relined or reconditioned for
reinstallation.
i
Mark shoe positions i f they are t o
CAUTION:
be r e i n s t a l l e d .
NOTE: The shoes should be replaced when
the lining is worn to approximately 1/32"
over the rivet heads. Replace shoes in axle
sets.
LIGHT DUTY TRUCK SERVICE MANUAL
BRAKES 5 -2 9