Brake Drum Refinishing; Anchor Pin Replacement; Wheel Cylinder - Chevrolet 10 1971 Series Chassis Service Manual

2: Make certain when installing drums
NOTE
that drums are installed in the same position as
when removed with the drum locating tang in
line with the locating hole in the wheel hub.
3. Make final adjustment by driving and stopping ve­
hicle until satisfactory brake pedal height is obtained
as described under "Self Adjusting Features" earlier
in this section.

BRAKE DRUM REFINISHING

Rear brake drums are demountable and may be re­
moved without removing the axle shaft.
A lanced "knock out" area is provided in the backing
plate for servicing purposes in the event retracting of
the brake shoes is required in order to remove the drum.
A small screw driver may be inserted to disengage
the automatic adjuster actuating lever so the star wheel
may be turned.
Removal
1. Place car on hoist.
2. Remove wheel and tire assembly, back off brake
adjustment if necessary and remove drum.
Inspection and Reconditioning
Whenever brake drums are removed they should be
thoroughly cleaned and inspected for cracks, scores, deep
grooves and out of round. Any of these conditions must be
corrected since they can impair the efficiency of brake
operation and also can cause failure of other parts.
Smooth up any slight scores by polishing with fine
emery cloth. Heavy or extensive scoring will cause ex­
cessive brake lining wear and it will probably be neces­
sary to rebore in order to true up the braking surface.
Out-of-round can only be accurately measured with
an inside micrometer fitted with proper extension rods.
All brake drums have a maximum dia­
NOTE:
meter cast into them.
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 REBORE
DIAMETER DIAMETER
11.060
11.000
12.060
12.000
13.000 13.060
Micrometer Method (Fig. 34)
1. Place the brake drum on a smooth surface.
2. Using micrometeters place the tips at the center of
the drum face.
3. While sweeping horizontally and vertically, slowly
adjust the micrometer until contact is made. Record
this reading.
4. Rotate the drim 45 degrees and repeat Step 3. Con­
tinue until 4 readings have been made. The difference
in these 4 readings must not exceed .006.
If drum is to be rebored for use with standard size
brake facings which are worn very little, only enough
metal should be removed to obtain a true smooth braking
surface.
A brake drum must not be rebored more than .060"
over the maximum standard diameter, removal of more
metal will effect dissipation-of heat.
This diameter is the
DISCARD
DIAMETER
11.090
12.090
13.090
Cleaning
New brake drums in parts stock are given a light coat­
ing 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, which
might cause an extreme brake grab condition.
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 that may later cause difficulty.
Installation
1. Make brake adjustment as outlined in this section.
2. Install brake drum, aligning tang with wheel hub.
3. Install wheel and tire assembly and lower vehicle.
4. Make final brake adjustment as outlined in this
section and check brake operation.

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.
This flange plate anchor pin fastener is
NOTE:
an important attaching part in that it could affect
the performance of vital components and sys­
tems, and/or could result in major repair ex­
pense. It must be replaced with one of the same
part number or with an equivalent part if re­
placement becomes necessary. Do not use a
replacement part of lesser quality or substitute
design. Torque values must be used as specified
during reassembly to assure proper retention
of this part.
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

Always use denatured alcohol or brake
NOTE:
fluid to clean any main cylinder or wheel cylinder
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, causing them to become soft and swollen
in an extremely short time.
BRAKES 5-15
10-30 CHEVROLET TRUCK SERVICE MANUAL