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GROUP 2-Bra
kes
CLEANING AND INSPECTION
D I S C ( F R O N T ) BRAKES
1. Remove the wheel and tire, cali-
per splash shield, and the shoe and lin-
ing assemblies as outlined in Part
2-2, Section 2.
2.
Make three thickness measure-
ments with a micrometer across the
middle section of the shoe and lining.
Take one reading at each side and
one in the center. If the assembly has
worn to 'a thickness of 0.231 inch
(shoe and lining together) or 0.066
inch (lining material only) at any
one of the three measuring locations
or if the brake lining shows evidence
of
brake fluid contamination, re-
place all four shoe and lining as-
semblies on both front wheels.
3. Check the caliper to spindle
attaching bolt
and caliper bridge
bolt torque. Tighten them to the
specified torque, if required.
4. To check rotor runout, first
eliminate the wheel bearing end play
by
tightening
the
adjusting
nut.
After tightening the nut check to see
that the rotor can still be rotated.
5. Clamp a dial indicator to the
caliper housing so that the stylus
contacts the rotor at a point approxi-
mately I inch from the outer edge.
Rotate the rotor and take an indica-
tor reading. If the reading exceeds
0.002 inch total lateral runout on
the indicator, replace or resurface
the disc brake rotor.
The following
requirements must be met when re-
surfacing disc brake rotors:
Rotunda Disc Brake Attachment
FRE-2249-2
is the
only approved
tool
to
be
used to refinish the disc
brake rotors. The step-by-step resur-
facing procedure provided with the
tool must be adhered to.
The finished braking surfaces of
the rotor must be flat and parallel
within 0.0007 inch; lateral runout
must not e x u e d 0.002 inch total
indicator reading, and the surface
finish o f the braking surfaces are
to be 85/15 micro inches.
The min-
imum limiting dimensions (Fig. 10)
from the inboard bearing cup to
the outboard rotor face (dimension
A ) and from the inboard bearing
cup to the inboard rotor face (di-
mension
B)
must be observed when
removing material from the rotor
braking surfaces.
When the runout check is finished,
be sure to adjust the bearings as
outlined in Group 3, in order to pre-
vent bearing failure.
6. Check the rotor for scoring.
Minor scores can be removed with a
fine emery cloth. If the rotor is exces-
sively scored, refinish it as outlined
in step 5 or replace the rotor, if re-
quired.
7. Visually check the caliper. If
excess leakage is evident, it should
be replaced. Slight leakage around
the pistons or seized pistons indicate
removal and disassembly:
.
8. If upon disassembly the cali-
per is found to be distorted or dam-
aged, or if the cylinder bores are
scored or excessively worn, replace
the assembly
.
The two halves of the caliper as-
sembly should never be separated.
Damage or failure of one requires
replacement of both as a unit.
REAR BRAKES
1. Remove the wheel from the drum,
then remove the drum as outlined in
Part 2-2, Section 2. Wash all the
parts except the brake shoes in a
cleaning solvent and dry with com-
pressed air.
2.
Brush all dust from the back-
ing plates and interior of the brake
drums.
3. Inspect the brake shoes for ex-
cessive lining :wear or shoe damage.
I f the lining is worn to within 1/32
inch of the rivet heads or if the shoes
are damaged, they
must
be
re-
placed. Replace any lining that has
been contaminated with oil, grease
or brake fluid. Replace lining, in
axle sets. Prior to replacement of
lining, the drum diameter should be
checked to determine if oversize linings
must be installed.
4. Check the condition of the brake
shoes, retracting springs, and drum
for signs of overheating. If the springs
show any loss of load or change in
free length indicating overheating,
LATERIAL RUNOUT
0.002 MAXIMUM TOTAL
INDICATOR READING
BEARING CUP
DIMENSION "B"
1 . 1 1 7 MINIMUM
DIMENSION "A"
0.402 MAXIMUM
SURFACE FINISH-
/IS
MICRO INCHES
H1%3-A
FIG.
10-Disc
Brake Rotor Service
Limits
-
Typical
replacement of the retracting and
hold down springs and the parking
brake cable is necessary.
Overheated
springs lose their pull and could
cause the new lining to wear pre-
maturely if they are not replaced.
5.
If the car has 30,000 or more
miles of operation, or signs of ex-
treme overheating are present when
relining brakes, the wheel cylinders
should be disassembled and inspected
for wear and dirt in the cylinder. The
cylinder cups and other parts con-
tained in the overhaul kit should be
replaced thus avoiding future prob-
lems.
6. Inspect all other brake parts
and replace any that are worn or
damaged.
7. Inspect the brake drums and,
if necessary, refinish. Refer to Part
2-2,
Section 4 for refinishing.
BOOSTER U N I T
Check the booster operation as
noted in Part 2-1, Section 1, Power
Brake Functional Test. If the brake
booster is damaged or defective, re-
place it with a new booster.
The
booster is serviced only as an assem-
bly.
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