Power Brakes

BRAKES
8-1
GENERAL DESCRIPTION
The braking system used on all 1963 Cadillac
cars consists of power- assisted, hydraulicallyoperated front and rear service brakes and a
foot-operated,
vacuum-released parking brake
that applies the brake shoes at the rear wheels
through mechanical linkage.
phragm, and a power piston return spring. The
control valve assembly consists of a single poppet
with a filtered atmospheric port and a vacuum
port. The reaction mechanism, integral with the
power piston assembly, controls the degree of
power brake application or release in accordance
with pressure applied to the valve operating rod
through the brake pedal linkage. The reaction
mechanism in the Bendix unit consists of a rubber
disc whereas, a reaction plate and levers are
used in the Delco Moraine unit.
Two different power brake units are used in
1963 production: Bendix and Delco Moraine.
These units are similar in outward appearance
and operation but vary considerably in internal
construction. For identification the Bendix unit
is painted all black, while the vacuum cylinder
of the Delco Moraine unit is zinc plated.
The master cylinder in both types of power
units is designed so that the front and rear brakes
have separate hydraulic systems. The primary
rear section of the master cylinder provides
fluid for the front brakes, while the secondary
front section provides fluid for the rear brakes.
Should a leak occur in the front wheel hydraulic
system, the rear lines and wheel cylinders would
still function. Likewise, if the rear hydraulic
system should leak, the front brakes would still
function. Increased pedal travel would warn the
driver that such a condition had occurred.
Both power brake units are of the vacuum sus
pended diaphragm type, utilizing engine intake
manifold vacuum and atmospheric pressure to
provide power-assisted application of the hy
draulic service brakes. The power units are
composed of two main sections; a vacuum power
section and a split system type hydraulic master
cylinder.
The vacuum power section of both the Bendix
and Delco Moraine units, Figs. 8-i and 8-2, con
sists of a front and rear shell, a power piston
assembly that houses the control valve assembly
and reaction mechanism, a vacuum power dia
A Vacuum
unit permits
with vacuum
or after any
Seal Ring
Piston Stop And
Seal Assembly
Fluid Reservoirs
check valve at the inlet to the power
several applications of the brakes
assist after the engine has stopped
other loss of vacuum supply. When
Front Shell
Rear Shell
Compensating Port
Valve Plunger
Inlet Port
1
Hub Seal
Valve Poppet
Air Filter
Secondary
SIlc
Dust Guard
Compensating Holes
F
Power Diaphragm Return Spring
Check Valve
/
Power Diaphragm
Fig. 8-.]
Bendix Power Brake Unit
Power Piston
BRAKES
8-2
the vacuum stored in the unit is used, or in case
of vacuum failure at the unit, the brakes can be
applied in the conventional manner. However,
more effort is required due to the loss of power
assist.
are used on the front wheel brake assemblies to
provide additional vibration control.
The wheel cylinders are of the double piston
type and are made of sintered iron to resist
corrosion and sticking. A metal expander is used
in each piston cup to prevent brake fluid leakage
and reduce the possibility of air entering the
system during expansion and contraction of the
fluid.
The non-adjustable anchor on each brake as
sembly is stationary and precision-located for
efficient braking.
The starwheel adjuster assemblies incorporate
spring steel thrust washers between the adjusting
screw and the adjuster end cap. These washers
provide a spring-cushioned contact between the
primary and secondary brake shoes, thus reducing
the possibility of vibration and squeak when the
brakes are applied. Brake shoe stabilizer plates
The parking brake automatic release mechanism
is operated by a vacuum diaphragm. When the
transmission selector lever is moved into any
drive position, with the engine running, a vacuum
valve in the neutral safety switch opens, evacu
ating air from the diaphragm assembly, which
Power Piston
Return Spring
Fluid Reservoirs
1i:- fl
Finned, cast iron brake drums with extended
flanges are used on both the front and rear wheels
to provide maximum brake cooling.
The parking brake assembly is mounted on the
cowl to the left of the steering column. The park
ing brake will release automatically when the
transmission selector lever is moved into any
drive position with the engine running. It will
not release automatically, however, with the en
gine running and the selector lever in neutral or
park, or in any position with the engine off. A
manual release, located on the upper end of the
parking brake assembly, may be used if the auto
matic release is inoperative or if manual release
is desired at any time.
The service brakes have self-adjusting brake
shoe mechanisms that assure correct lining-todrum clearances at all times. The automatic
adjusters operate only when the brakes are ap
plied as the car is moving rearward or when the
car comes to an uphill stop.
Compensating Port
The brake linings are riveted to the shoes.
The primary linings are grooved at the center
to permit dissipation of heat from the surface
of the brake drum, resulting in better brake per
formance and longer lining life.
.
Diaphragm
Re1ta1iing Ring
Reaction Plate
Por
FL
Piston
Spring
-
/ Reaction Levers
Air Valve
Air Valve Spring
,/"Retainer
cliencer
.Air
71 flTF
7/
/
Headnut
Floating
Floating
Piston
Piston I
Spring Retainer
Seconaary Stop I
Primary Sea
Protector Washer Seals
Primary
/
V
/
Piston Spring
Primary
Piston
Protector
Washer
Primary Seal
Spring Retainer
/
/
/
Secondary Seal
Front Shell
Fig. 8-2
Delco Moraine Power Brake Unit
Filter
Push Rod
Dust Guard
Bearing Seal
N51
Band
Floating Control Valve
Power Piston Insert
Hydraulic
‘Rear Shell
Push Rod
BRAKES
in turn disengages the locking mechanism, per
mitting the parking brake pedal to return to its
released position by spring action.
The brake stoplight switch is mounted on a
flange protruding from the brake pedal support
8-3
bracket below the instrument panel. When the
brake pedal is depressed, the spring loaded
switch plunger follows the brake pedal arm down
ward until the switch is in the "on" position.
When the brakes are released, the arm returns
the switch plunger to the "off" position.
SERVICE INFORMATION
1. Manual Brake Shoe Adjustment
Although the hydraulic service brakes are selfadjusting, a preliminary star wheel adjustment is
necessary after the brake shoes have been relined
or replaced, or when the length of the star wheel
adjuster has been changed during some other
service operation. Final adjustment is made auto
matically by adjusters that function when the car
is moving backward.
1. Check fluid level in both master cylinder
reservoirs. Fluid level should be approximately
3/4 inch from top of each filler hole boss. Add
fluid if necessary.
2. Check front wheel bearing adjustment and
correct if necessary. See Section 4, Note 5.
3. Check to make certain that parking brake
cable and linkage, including levers on rear sec
ondary shoes, are free.
4. Tighten star wheel until brake drum cars just
be rotated forward with a two-foot bar placed
between the studs.
5. Disengage adjuster pawl from star wheel
with a hooked tool and back off star wheel 40
notches with screwdriver or brake adjuster tool.
Fig. 8-3.
6. Install wheels and lower car.
7. Drive car alternately forward and backward,
applying brakes moderately in each direction until
pedal travel does not exceed 1-7/8 inch on a mod
erate approximately 30 pound brake pedal
application.
2. Parking Brake Adjustment
NOTE: In order to adjust parking brakes on
1963 Cadillac cars, it will be necessary to make
a gage using 3/16 inch flat steel according to
pattern shown in Fig. 8-4.
1. Make sure that service brakes are properly
adjusted before adjusting parking brake.
2. Lubricate complete parking brake linkage
with special heat resistant lubricant, and check
for free movement of cables in conduit and in
equalizer.
3. Check relay lever return spring and replace
if weak or broken.
4. With mechanism in released position, check
for proper tension of front cable by inserting
13/16 inch portion of Parking Brake Gage between
relay lever and end of slot in frame, Fig. 8-4.
Gage must fit in slot with clearance of less than
5/16 inch. If necessary, adjust front cable by
aligning one of three clevis holes with one of two
relay lever holes to provide proper gage fit.
5. Back off parking brake equalizer nut until
relay lever can be moved forward enough to slip
Checking Tension
Of Front Cable
Fig. 8-3
Manual Brake Shoe Adjustment
Fig. 8-4
Parking Brake Adjustment
BRAKES
8-4
1-13/16 inch wide end of gage between relay lever
and end of slot in frame, Fig. 8-4.
NOTE: Be certain that equalizer nut has
been backed off enough to leave cable slack
when 1-13/16 inch wide end of gage is in place.
6. Tighten equalizer nut until a near lock-up
drag is obtained at the rear wheels when they are
turned by hand in a forward direction.
7. Remove gage from relay lever slot in frame
side bar.
Those Service Departments that have adequate
brake shoe relining equipment can obtain linings,
drilled and cut to size, from factory Parts Ware
houses. Brake lining grinding equipments should
incorporate brake shoe holders that locate the
shoes accurately in relation to the anchor end,
as brake anchors are not adjustable and require
accurately ground linings.
4. Relining Brakes Fig. 8-5
a. Front Brakes
1. Raise car and remove front wheels.
NOTE: After adjustment is performed, park
ing brake pedal should travel 1-3/4 inches to
2-3/4 inches with approximately 50 pounds
force on pedal.
2. Remove front brake drum assemblies.
CAUTION: When handling brake drums, be
extremely careful not to get any dirt in front
wheel bearings.
3. Brake Shoe Assemblies
When brake relining is necessary, it is recom
mended that the complete brake lining and shoe
assemblies be replaced with new assemblies. New
lining and shoe assemblies are precision-ground
to fit a twelve inch drum diameter, minimizing the
possibility of imperfect braking action due to
warped brake shoes or partial contact between
linings and drum. This simplifies the complete
relining operation and insures a satisfactory job
for the customer.
-z
Anchor
Actuating Lever
4. Remove primary brake shoe hold-down cups,
spring, and pin, and secondary brake shoe holddown cup, spring, pin, and sleeve.
5. Remove pawl return spring, actuating lever,
pawl, and link.
Anchor Bolt
Shoe Guide Plate
Lock
Plate
/Retracting Spring
Hold Down
Cups
/
Operating
Lever
3. Remove primary and secondary brake shoe
retracting springs using Brake Spring Remover
and Installer, J-8049.
Primary To
Secondary Spring
Pj
Paw1 Return Spring
Fig. 8-5
tar
Wheel
Adjusting Screw
7
Primary Shoe
Primary To Secondary Spring
Front and Rear Wheel Brake Mechanisms Right Side
BRAKES
8-5
6. Disengage brake shoes from wheel cylinder
connecting links and remove complete shoe and
lining assembly from brake backing plate.
7. Remove star wheel adjuster and primary- tosecondary connecting spring from shoe assembly.
8. Remove cups, springs, and pins from stabi
lizer plates and remove plates.
9. Clean brake
parts.
backing
plate
Adjusting Screw
Spring Washer
Pivot
Socket
Nut
Identification Grooves
and all brake
CAUTION: To avoid the possibility of brake
"grab" or "pull" after brake service has been
performed, make certain that hands are clean
when handling brake parts and avoid handling
friction surfaces of drums and linings as much
as possible.
10. Tighten attaching bolts that hold front back
ing plate to steering knuckle to 65 foot-pounds
torque.
11. Lubricate threads and socket of star wheel
adjuster and points of contact between brake shoe
and other brake parts with special heat resistant
lubricant which should be used sparingly, espe
cially on brake shoe pads.
12. Thread star wheel adjusting screw com
pletely into pivot nut to permit installation of
brake drum over replacement brake shoes.
13. Install star wheel adjuster and primary-tosecondary connecting spring on replacement brake
shoes.
NOTE: Black spring is used on right side of
car and yellow spring on left side. These
springs are not interchangeable.
Star wheel adjusters with three wide grooves on
O.D. of pivot nut left hand threads are installed
on right side of car and those with three narrow
grooves on O.D. of pivot nut right hand threads
must be installed on left side. The three narrow
grooves on the socket are for manufacturer’s
identification only. Sockets are interchangeable,
left and right. Incorrect installation of star wheel
adjusters would result in automatic adjusters
loosening rather than tightening brakes. Be sure
small diameter thin thrust washer, Fig. 8-.6, i
installed between end socket and large diameter
spring steel washer in adjuster assembly.
14. Position shoe assembly on brake backing
plate so that shoes engage wheel cylinder con
necting links.
15. Position primary stabilizer plate over pri
mary brake shoe and install hold-down pins, cups
and springs. Install red spring on primary shoe
first, for easier installation.
NOTE: A red spring is used at the middle of
the primary shoe and a yellow spring at the
center of the primary stabilizer plate. A blue
Thrust Washer
Fig. 8-6
Star Wheel Adjuster Assembly Right Side
spring is used on the secondary shoe and a yel
low spring at the center of the secondary stabi
lizer plate.
16. Position secondary stabilizer plate over
secondary brake shoe, then position actuating
lever and pawl so that actuating lever is on top
of secondary stabilizer plate. Secure with holddown pin, sleeve, spring and cup.
17. Install hold-down pin, cups, and spring at
center of stabilizer plates.
18. Install pawl return spring and link. Make
certain that star wheel engages pawl.
19. Install black primary and yellow secondary
brake shoe retracting springs using Brake Spring
Remover and Installer, J-8049.
20. Wipe steering knuckle clean and apply a
thin film of wheel bearing grease on spindle.
21. Install front brake drums and adjust wheel
bearings as described in Section 4, Note 5.
CAUTION: Do not let any grease or oil get
on drums or linings.
22. Perform preliminary service brake adjust
ment as described in Note 1.
23. Install wheels on brake drums.
wheel mounting nuts to 105 foot-pounds.
Tighten
b. Rear Brakes
1. Release parking brake,
move rear wheels.
raise car, and re
2. Remove rear brake drum assemblies.
3. Loosen
equalizer.
parking
brake
cable
lock
nut on
4. Remove primary brake shoe retracting
spring using Brake Spring Remover and Installer,
J- 8049.
8-6
BRAKES
5. Disconnect link at anchor and remove link,
secondary brake shoe retracting spring, and an
chor plate.
6. Remove primary brake shoe hold-down cups,
spring and pin, and secondary brake shoe holddown pin, cup, spring, and sleeve.
7. Remove pawl return spring, actuating lever,
and pawl.
8. Disengage brake shoes from wheel cylinder
connecting links and parking brake strut rod. Re
move strut rod and spring.
must be installed on left side. The three narrow
grooves on the socket are for manufacturer’s
identification only. Sockets are interchangeable,
left and right.
18. Position shoe assembly on brake backing
plate and connect parking brake cable to operating
lever.
19. Install parking brake strut rod and spring
on brake shoe assembly.
NOTE: Spring tab must be positioned outside
of brake shoe web on left rear brake and inside
of web on right rear brake.
9. Disconnect parking brake cable from oper
ating lever on secondary shoe and remove com
plete shoe and lining assembly from brake backing
plate.
20. Engage shoes with wheel cylinder connect
ing links and install hold-down pin, cups, and
spring on primary brake shoe.
10. Remove star wheel adjuster and primary to
secondary connecting spring from shoe assembly.
NOTE: Red primary and blue secondary
hold-down springs are used on the rear brake
assembly.
11. Remove clip from pin on secondary brake
shoe and remove operating lever and pin
assembly.
12. Clean brake backing plate and all brake
parts.
CAUTION: To avoid the possibility of brake
"grab" and "pull" after brake service has been
performed, make certain that hands are clean
when handling brake parts and avoid handling
friction surfaces of drums and linings as much
as possible.
13. Tighten bolts that hold backing plate to rear
axle housing to 40 foot-pounds 70 foot-pounds on
commercial chassis.
14. Install operating lever and pin assembly on
replacement secondary brake shoe and secure
with clip.
15. Lubricate threads and socket of star wheel
adjuster and points of contact between brake and
other brake parts with special heat resistant lu
bricant which should be used sparingly, especially,
on brake shoe pads.
16. Thread star wheel adjusting screw com
pletely into pivot nut to permit installation of
brake drum over replacement brake shoes.
17. Install star wheel adjuster and primary- tosecondary connecting spring on brake shoes. Make
certain that star wheel rotates in proper direction.
NOTE: Red springs are used on both left
and right hand rear brake shoe assemblies.
These springs are interchangeable.
Star wheel adjusters with three wide grooves on
O.D. of pivot nut left hand threads are installed
on right side of car and those with three narrow
grooves on O.D. of pivot nut right hand threads
21. Position actuating lever and pawl so that
actuating lever is on top of secondary brake shoe.
Secure with hold-down pin, sleeve, spring, and
cup.
22. Install anchor plate,
brake shoe retracting spring
installation, first connect
install link on anchor, using
er and Installer, J-8049.
link, and secondary
yellow. For easiest
spring to link, then
brake Spring Remov
23. Install pawl return spring.
that star wheel engages pawl.
Make certain
24. Install primary brake shoe retracting
spring red using Spring Installer, J-8049.
25. Install rear brake drums on rear axle shaft
flange and secure with two screws.
26. Perform preliminary service brake adjust
ment as described in Note 1.
27. Install wheels on brake drums.
wheel mounting nuts to 105 foot-pounds.
Tighten
28. Adjust parking brake as described in Note 2.
5. Machining Brake Drums
Brake drums should be carefully checked to see
if they have become warped or scored excessively.
If they appear salvable, they can be machined if
suitable equipment is available.
Drum machining is a precision operation and
equipment used for this purpose must be capable
of maintaining the close limits specified. Be sure
to install drum in the machining equipment cor
rectly and to check runout of lathe spindle to in
sure accuracy of final machining operation. Inside
___
BRAKES
drum diameter must not be machined over
12.060 inch. Should brake drums be machined too
thin, the intense heat that develops under severe
driving conditions will cause them to distort or
warp.
Replacement brake drums supplied by factory
Parts Warehouses are finish machined at the
factory before being shipped. They do not require
any further finishing before installation, but they
must be thoroughly cleaned with a non-oil base
solvent to remove all traces of the oil or llrease
used for rust proofing during storage and transit.
Do not machine drums to roughen the braking
surface. Use coarse emery cloth for this purpose.
6. Break-In of New Linings
New or replacement brake linings, if subjected
to normal usage at speeds under 50 MPH, need no
special break-in. However, the first few brake
applications may be somewhat erratic, and Serv
icemen may need to stabilize the brakes before
delivering the car to the owner. If brake action is
erratic, one acceptable way to seat the brakes is
to make five or ten moderate brake stops at
speeds of 30 to 40 MPH, at approximately one
quarter mile intervals.
Severe break-in is apt to produce small charred
flakes on the lining surface which will produce a
decided pull. If this should occur, lining surface
should be sanded slightly to remove any flakes.
Use only common sandpaper for this purpose so
that all abrasive particles can be removed with
the lining dust by careful use of clean compressed
air.
7. Wheel Cylinder Removal,
Disassembly and Cleaning
a. Removal
1. Raise car and remove wheel and brake drum.
Blow out dust and dirt from drum and li:rsings,
being careful not to blow dirt around wheel
bearing areas.
8-7
Bleeder Screw
Piston Cup
Piston
Boot
Cup Expanders
/
Connecting Link
/
/
Piston Cup
Boot
Piston Cup Spring
N
Connecting Link
Wheel Cylinder
Piston
Fig. 8-7
Wheel Cylinder Disassembled
b. Disassembly, Fig. 8-7
1. Remove connecting links and rubber boots
from ends of wheel cylinder.
2. Slide pistons and piston cups from either end
of cylinder.
3. Remove
assembly.
piston
cup
spring
and
expander
4. Remove bleeder screw assembly.
c. Cleaning
With clean hands, wash all parts except pistons
in clean alcohol. Wipe pistons with clean dry
cloth. Inspect surface of cylinder bore and hy
draulic passages. Replace wheel cylinder if any
obstructions are observed in drilling holes or if
there are any nicks or burrs in bore.
8. Wheel Cylinder
Assembly and Installation
a. Assembly, Fig. 8-7
1. Install bleeder screw assembly.
2. Install piston cup in one end of cylinder with
lip toward center, and install piston with flat side
toward cup.
3. Place rubber boot over end of wheel cylinder.
4. Install spring and expender assembly.
2. Remove hydraulic brake hose as described
in Note 11.
5. Install other piston cup, lip toward center.
Install piston, flat side toward cup.
3. Remove brake shoe retracting springs and
link.
6. Install remaining rubber boot over end of
cylinder.
4. Remove two screws holding wheel cylinder
to backing plate.
b. Installation
5. Disengage wheel cylinder connecting links
from brake shoes and remove wheel cylinders.
1. Position wheel cylinder on brake backing
plate, slipping cylinder- to- shoe connecting links
in place at same time.
CAUTION: Be sure brake fluid does not drip
on brake linings.
2. Install two screws holding wheel cylinder to
backing plate.
BRAKES
8-8
3. Install brake shoe retracting
link.
springs
and
4. Install hydraulic brake hose as described in
Note 11.
5. Install
brake
drum and
wheel
assembly.
6. Bleed line to brake wheel cylinder that was
removed as explained in Note 9.
2. Build up pressure in bleeder.
3. Attach drain hose to bleeder fitting on each
rear wheel cylinder in turn.
4. Back off rear brake bleeder fitting three
quarters of a turn and bleed brake fluid into a
partially filled bottle of clean brake fluid until
bubbles stop, then close fitting.
NOTE: Avoid handling friction surfaces of
drums and linings as much as possible.
5. Connect bleeder hose to rear master cylin
der reservoir and repeat procedure for front
wheel cylinders.
7. Lower car.
c. Alternate Method
9. Bleeding Brakes
Bleeding brakes may be made considerably
easier through use of one of the pressure brake
bleeder tools available. This equipment consists
of a tank partially filled with brake fluid and
rubber hose that connects to the hydraulic cyl
inder reservoir. Air pressure is developed in the
tank to force fluid into the brake system.
After bleeding brakes, check pedal travel as
described in Note 1, Step 7. Rebleed or adjust
brakes as necessary.
CAUTION: Do not spill brake fluid on car
finish or damage will result.
a. Bendix Brake Unit
1. Remove master cylinder reservoir
caps and fill both reservoirs with fluid.
2. Connect
bleeder
hose
filler
to front reservoir.
3. Install solid filler cap on rear reservoirs.
NOTE: A solid filler cap can be made by
welding the vent hole closed on any metal filler
cap.
If a pressure bleeder is not available, the fol
lowing two-man procedure may be used for either
unit.
1. Fill both master cylinder reservoirs with
brake fluid. Keep reservoirs at least partially
filled at all times during bleeding operation.
2. Back off both master cylinder outlet pipe
nuts one turn and completely pump brake pedal
five times, catching fluid displaced from outlets
in a cloth or can. Discard this fluid and re
tighten outlet pipe nuts.
3. Attach drain hose to fitting on wheel cylinder
and suspend loose end of hose into partially filled
bottle of clean brake fluid.
4. Apply pressure to brake pedal, back off
bleeder fitting one quarter turn, and depress
brake pedal. Close bleeder fitting before releasing
pressure on brake pedal. Repeat pedal applica
tions until bubbles stop.
5. Bleed each wheel cylinder in turn, following
this same procedure.
10. Stoplight Switch Removal,
Installation and Adjustment
a. Removal
4. Build up pressure in bleeder.
5. Attach drain hose to bleeder fitting on wheel
cylinder.
6. Back off fitting three quarters of a turn and
bleed brake fluid into a partially filled bottle of
clean brake fluid until bubbles stop, then close
fitting.
1. Disconnect two lead wires
switch, Fig. 8-8.
from stoplight
2. Remove front
switch.
from
locking
nut
stoplight
3. Remove stoplight switch.
b. Installation
7. Repeat
cylinder.
this
operation
for
each
wheel
1. Position
Fig. 8-8.
switch on
pedal
b. Delco Moraine Unit
2. Install front locking nut.
1. Connect bleeder hose to front master cyl
inder reservoir.
3. Connect lead wires to switch.
bracket
flange,
BRAKES
8-9
b. Installation
1. Install new copper gasket on cylinder end of
hose male end.
2. Tighten hose in wheel cylinder inlet securely.
3. With suspension in normal position front
wheels straight ahead pass female end of hose
through frame support bracket, allowing hose to
seek its own position. Insert hex of hose fitting
into the 12 point hole in support bracket in po
sition that induces least twist in hose.
NOTE: Do not twist hose any more than
necessary during this operation as its natural
curvature is absolutely necessary to maintain
proper hose- to- suspension clearance through
full movement of suspension and steering parts.
Fig. 8-8
Stoplight Switch
4. Check operation of stoplight.
c. Adlustment
Adjust switch action so that stoplight is on when
brake pedal is depressed 1/2 inch, Fig. 8-8.
Loosen front and rear nuts that hold stoplight
switch and move switch up or down until this
action is obtained. Tighten switch lock nuts se
curely to prevent loss of adjustment.
11. Hydraulic Brake Hose Service
Hydraulic pressure is transferred from the
steel brake lines to the wheel cylinders by means
of flexible hoses. These flexible hoses are de
signed and constructed to withstand any stress
that may be encountered during the course of
normal driving.
While the flexible hoses require no particular
servicing, they should be inspected every Spring
and Fall for damage that may occur from various
road hazards. Replace damaged hoses in follow
ing manner:
a. Removal
1. Disconnect steel brake line from hose by
turning steel tube connector nut out of hose fitting.
Cap fitting to prevent dirt from entering brake
line.
4. Install "U" shaped retainer to secure hose
in frame support bracket.
5. Inspect by turning steering from stop-to-stop
while observing hose position. Be sure that hose
does not touch other parts at any time during
suspension or steering travel. If contact does
occur, remove hose retainer and rotate female
hose end in support bracket one or two points in
appropriate
direction,
replace retainer, and
reinspect.
6. Place steel tube connector nut in hose fitting
and tighten securely, being careful not to damage
threads.
CAUTION: Never tighten hose in wheel cyl
inder inlet with hose attached at frame ends as
this will twist the hose.
7. I3leed all
brakes
as
outlined
in Note 9.
12. Parking Brake Preliminary Checks
It is not always necessary to replace the parking
brake assembly or diaphragm in cases of an in
operative parking brake automatic release. The
following checks should be performed as part of
your diagnosis to determine the cause and cor
rection of parking brake trouble and to eliminate
brake
unnecessary
replacement
of parking
components.
2. Remove "U" shaped retainer from hose
fitting and withdraw hose from frame support
bracket.
1. Check for damaged or kinked vacuum hoses
and for loose hose connections at parking brake
diaphragm, vacuum release valve at neutral safety
switch, and at engine manifold connection.
3. Turn hose fitting out of wheel cylinder inlet
and remove copper gasket. If hose is to be re
installed, cover end fittings to prevent dirt from
entering hose.
2. Check adjustment of neutral safety switch
and operation of vacuum release valve. Correct
as necessary and recheck parking brake operation.
BRAKES
8-10
3. Check diaphragm piston travel by running
engine and moving transmission selector lever
from drive to neutral. The manual release lever
should move up and down as vacuum is applied and
released. If no movement is observed, or if move
ment is slow, more than one or two seconds to
complete the full stroke diaphragm is leaking.
Replace diaphragm as described in Note 14.
4. Check brake release with vacuum applied.
If diaphragm piston completes full stroke but does
not release brake, a malfunction of the pedal
assembly is indicated. Replace complete parking
brake assembly as described in Note 13.
5.
off.
less
not,
Check operation of parking brake with engine
Parking brake should remain engaged regard
of transmission selector lever position. If
replace parking brake assembly.
5. Remove two parking brake assembly-to-cowl
mounting nuts and move assembly away from cowl.
6. Push brake lever to fully engaged position so
that clevis on parking brake assembly is exposed,
and depress spring retainer to remove parking
brake cable from clevis.
NOTE: Spring retainer is used to facilitate
installation of cable at time of assembly. It is
not required for proper operation of parking
brake.
b. Installation
1. Attach parking brake cable to clevis on park
ing brake assembly.
2. Install parking brake assembly to studs on
cowl with two mounting nuts.
13. Parking Brake Assembly
Removal and Installation
3. Install two parking brake
instrument panel mounting bolts.
a. Removal
1. Disconnect parking brake
lever underneath car, Fig. 8-9.
2. Disconnect
4. Position carpet and left cowl kick-pad out of
the way and remove KB board.
hose
cable at
from vacuum
3. Remove two parking brake
instrument panel mounting bolts.
Parking Brake Assembly
relay
diaphragm.
assembly-to-
assembly- to-
4. Install KB board and replace cowl kick-pad
and carpet.
5. Connect hose to vacuum diaphragm.
6. Connect front cable at relay lever underneath car.
Parking Brake
Release Lever
Equalizer
Parking Brake Cables
Lever
Return Spring
Strut Rod
Parking Brake Cable
Fig. 8-9
Parking Brake Linkage
BRAKES
8-11
7. Adjust parking brake linkage as described in
Note 2.
8. Check operation of automatic release.
14. Parking Brake Diaphragm
Removal and Installation
a. Removal
1. Remove parking brake assembly as described
in Note 13.
2. Drill out two rivets retaining diaphragm on
60 and 62 series cars. On Seventy-Five series
cars and commercial chassis it is only necessary
to straighten retaining tangs to remove diaphragm
Fig. 8-10
Power Brake Unit Installed
3. Drill out or grind off rivet that connects link
to manual release lever and remove diaphragm
on 60 and 62 series cars. On Seventy-Five series
cars and commercial chassis, disconnect link
from manual release lever.
spacer that attach power unit push rod to brake
pedal relay lever.
b. Installation
b. Installation
1. On 60 and 62 series cars, position diaphragm
on parking brake assembly and secure with two
rivets. Secure link to manual release lever with
special shoulder screw and nut.
1. Position power brake unit on cowl and install
four retaining nuts loosely.
2. On Seventy-Five series cars and commercial
chassis, position diaphragm on parking brake
assembly, and secure by bending diaphragm re
taining tangs. Connect link to manual release
lever.
3. Install parking brake assembly as described
in Note 13.
4. Test automatic lock and release operations
with engine running in "neutral" and "drive"
range.
NOTE: Parking brake should release in any
drive range with engine running. Parking brake
should remain engaged in "neutral" or "park"
with engine running.
2. Attach power unit push rod to brake pedal
arm pin with spring spacer, washer, and cotter
pin.
3. Tighten four brake unit retaining nuts.
4. Connect vacuum hose to vacuum check valve
on power brake unit, Fig. 8- 10.
5. Connect hydraulic brake lines to master
cylinder. Front wheel brake line goes to fitting
nearest cowl.
16. Bendix Power Brake Unit
Disassembly, Cleaning, Inspection
and Assembly
a. Disassembly
1. Scribe a line on top center of front and rear
shells of power unit in line with master cylinder
filler caps.
15. Power Brake Unit
Removal and Installation
2. Place assembly in benchvise with rear shell
up and tighten vise jaws securely on master cylin
der, being careful not to crack casting.
a Removal
1. Disconnect hydraulic brake lines from mas
ter cylinder on power brake unit, Fig. 8-10. Cap
line fittings to prevent dirt from entering brake
lines.
2. Disconnect vacuum hose from vacuum check
valve on power brake unit.
3. Remove
4. Remove four retaining nuts that hold power
unit to cowl and remove power brake unit.
cotter
pin,
washer,
and
spring
3. To facilitate disassembly, connect vacuum
pump to check valve on front shell of power unit
and operate pump to obtain at least 15 inches
vacuum.
NOTE: If vacuum pump is not available, a
length of hose may be connected to car intake
manifold with engine operating at idle.
BRAKES
8-12
Rear Shell
I
Bearing Seal
Fig. 8-]]
Removing Bendix Power Unit Rear Shell
4. Install Power Unit Shell Separator, J-9504,
over mounting studs on rear shell and rotate rear
shell counterclockwise to disengage from front
shell, Fig. 8-11.
5. Disconnect vacuum pump and then work push
rod several times to empty master cylinder and
relieve vacuum in power unit.
6. Remove rear shell, power piston assembly,
and piston return spring, Fig. 8-12.
CAUTION: Be careful when removing Sepa
rator Tool, as internal piston return spring may
cause rear shell to fly off when pressure is
released.
Fig. 8-13
Removing Bearing Seal From Rear Shell
10. Remove valve plunger lock and remove con
trol valve and rod assembly.
11. Remove hydraulic push rod from diaphragm
plate.
12. Press rubber
phragm plate.
reaction
disc out of dia
7. Remove dust guard and retainer from rear
shell.
13. Remove front shell and master cylinder
from vise and remove vacuum check valve by
turning counterclockwise, then remove gasket.
Discard check valve and gasket.
8. Pry off filter retainer and remove silencer
and air filter from valve housing in diaphragm
plate, Fig. 8-12. Be careful not to scratch or chip
plastic housing.
14. Remove four nuts and lockwashers that re
tain master cylinder to front shell and remove
master cylinder. Remove seal ring and discard.
9. Remove rear shell from diaphragm plate
assembly and remove power diaphragm from dia
phragm plate.
15. Support rear shell on two wood blocks and
drive out bearing seal with screwdriver or punch,
Fig. 8-13. Discard bearing seal.
Control Valve
and Rod Assembly
Filter Retainer
Hydraulic Push Rod
Gasket
Reaction Disc
Air Filter
Rear Shell
Bearing Seal
Vacuum
Check Valve
Front Shell
Piston Return Spring
Valve Plunger Lock
Diaphragm Plate
Power Diaphragm
Dust Guard Retainer
Fig. 8-12
Bendix Power Unit Disassembled
BRAKES
8-13
b. Cleaning and Inspection
1. Tho:roughly wash all parts in clean alcohol.
NOTE: Use of gasoline, kerosene, anti
freeze, or any other cleaner with even a trace
of mineral oil will damage rubber parts.
Bearing
Seal
lnstaller.,.
J954O
2. Use air hose to blow out all passages, ori
fices, and valve holes. Air dry and place cleaned
parts on clean paper or lint-free cloth.
3. If slight rust is found inside front or rear
shell, polish clean with crocus cloth or fine emery
paper, washing clean afterwards.
4. Inspect front and rear shells for scratches,
scores, pits, dents or other damage affecting
rolling or sealing of diaphragm or other seals.
Small imperfections may be smoothed out with
fine crocus cloth.
5. Inspect power diaphragm for cuts, pin holes,
distortion or cracks.
Fig. 8-14
6. Inspect all other parts for distortion, dam
age, or excessive wear, and replace as necessary.
c. Assembly
Be sure all parts are clean before asserribling
unit. Do not let grease or mineral oil come in
contact with any rubber parts.
Lubricate rubber parts of power piston group
with special lubricant included in service kit.
1. Place rear shell on bench with mounting
studs up, Place new bearing seal on Bearing Seal
Installer, J-9540, with plastic side of seal next to
Installer, and drive seal into shell until flange of
Installer contacts surface of shell adjacent to
seal, Fig. 8-14.
2. Apply special lubricant to outer diameter of
diaphragm plate hub and bearing surfaces of valve
plunger and to outer edge of poppet valve.
3. Insert valve and rod assembly in valve
housing, pressing valve plunger and poppet into
diaphragm plate hub, Fig. 8-12.
4. Align slot in diaphragm plate with groove in
valve plunger and insert plunger lock.
5. Install power diaphragm in groove of dia
phragm plate.
6. Slide air filter and air silencer over valve
rod and guide into place in valve housing. Press
filter retainer on end of valve housing, using care
not to scratch or damage plastic housing.
7. Install
rear shell.
dust guard retainer
over studs on
Installing Bearing Seal in Rear Shell
8. Install dust guard over flange of dust guard
retainer and over flange of air filter retainer.
9. Place new vacuum check valve gasket on
front shell and install new check valve on front
shell. Press and turn valve clockwise to lock in
place, Fig. 8-12.
10. Place master cylinder in bench vise with
mounting flange up and place front shell of po.wer
unit on master cylinder with mounting bolts
through holes in flange. Install four lockwashers
and nuts.
11. Install piston return spring in front shell,
with smaller end down.
12. Apply special lubricant to bearing seal in
rear shell and install diaphragmS assembly into
rear shell, guiding valve housing through bearing
seal.
13. Position rear shell and diaphragm assembly
on piston return spring.
14. Connect vacuum pump to check valve on
front shell of power unit and operate pump to ob
tain at least 15 inches vacuum.
NOTE: If vacuum pump is not available, a
length of hose may be connected to car intake
manifold with engine operating at slow idle.
15. Install Power Unit Shell Separator, J-9504,
over mounting studs on rear shell and press rear
shell into front shell, aligning scribe marks so
that when shells are rotated into locked position,
scribe marks will line up. Rotate rear shell
clockwise to lock shells together, Fig. 8-11. Dis
connect vacuum pump and remove Separator Tool.
BRAKES
8-14
NOTE: The push rod is designed with a selflocking adjustment screw to provide the correct
relationship between vacuum piston and master
cylinder piston. This adjustment is very im
portant because it assures the compensating
port being kept open while unit is in released
position. Adjustment screw is set to the correct
height at time of assembly and, under normal
service, will not require further adjustment.
When unit has been disassembled, however,
adjustment should be checked to assure proper
height.
Fig. 8-15
19. Place Push Rod Height Gage, J-7723-Ol,
over push rod with legs of gage resting on front
shell of vacuum power unit, Fig. 8-15. Top of
screw should just touch gage.
Checking Push Rod Height Bendix
16. Remove power unit from master cylinder
and place unit on bench.
20. If adjustment is necessary, hold push rod
with pliers at serrated end and turn adjusting
screw either in or out as required.
17. Apply special lubricant to piston end of
push rod and to entire surface of reaction disc.
18. Place reaction disc on push rod and insert
push rod and disc into diaphragm plate. Press
and twist rod to make certain disc and rod are
bottomed in plate.
21. Install new seal ring in groove on hub of
master cylinder and attach master cylinder to
vacuum power unit with four lockwashers and
nuts. Tighten nuts to 17 foot-pounds.
Gasket
Gasket
Master Cylinder
Check Valve Spring
Spring Stop
Check Valve Spring
/
Secondary Spring
Piston Seal
Protector Washer
Residual Check Valves
Secondary Piston
Outlet Fitting
Piston Seals
Retainer
Spring
Spring Retainer
Adjusting
Piston Seal
Protector Washer
Primary Piston
Piston Stop and Seal Assembly
Snap Ring
Fig. 8-16
Bendix Waster Cylinder Disassembled
Gasket
BRAKES
8-15
17. Bendix Master Cylinder
Disassembly, Cleaning, Inspection
and Assembly
a. Disassembly
NOTE: If trouble has been tsraced to hy
draulic
system,
master cylinder may be
removed from vacuum unit without removing
complete power brake assembly from car. Area
surrounding master cylinder mounting surface
must be kept clean.
1. Disconnect primary and
lines if not done previously.
secondary
2. Remove four nuts and lockwashers and. re
move master cylinder from vacuum power unit.
Remove seal ring and discard.
3. Remove
assembly..
a
brake
filler caps from master cylinder
Fig. 8-18
Bendix Secondary Piston Disassembled
11. Remove seal retainer and two piston seals
from secondary piston.
b. Cleaning and Inspection
4. Remove outlet fitting, spring, and residual
check valve from rear outlet of master cylinder,
Fig.
8-16. Remove gasket from fitting and
discard.
5. Remove snap ring from groove in bore of
master cylinder.
6. Remove primary piston and stop assembly,
secondary piston and stop assembly, secondary
spring, spring stop, secondary check valve spring,
and check valve from master cylinder housing,
Fig. 8-16.
7. Remove brass piston stop and seal assembly
from primary piston, Fig. 8-17, and discard.
Piston stop is serviced as a unit and should not
be disassembled.
8. Remove retainer, piston seal, and protector
washer from primary piston.
9. Remove retainer, piston seal, and protector
washer from forward end of secondary piston
assembly, Fig. 8-18.
10. Remove spring adjusting screw, spring re
tainer, and spring from secondary piston.
Pi ston Stop And Seal Assembly
Piston Seal
Primary Piston
Retainer
Fig. 8-17
Bendix Primary Piston Disassembled
1. Thoroughly wash all parts in clean alcohol.
NOTE: Use of gasoline, kerosene, anti
freeze, or any other cleaner with even a trace
of mineral oil will damage rubber parts.
2. Use air hose to blow out all passage, ori
fices, and valve holes. Air dry and place cleaned
parts on clean paper or lint-free cloth.
3. Inspect master cylinder bore for scoring,
rust, pitting or etching. Any of these will require
replacement of master cylinder housing.
4. Inspect master cylinder pistons for scoring,
pitting or distortion. Any of these will require
replacement of piston.
NOTE: If either master cylinder housing or
piston are replaced. Throughly clean new
parts with alcohol and blow out all passages
with air hose.
5. Examine fluid reservoirs for foreign matter
and check all passages for restrictions. If there
is any suspicion of contamination or evidence of
corrosion, completely flush car hydraulic system,
using clean brake fluid.
6. When overhauling master cylinder, use all
parts furnished in master cylinder repair kit.
c. Assembly
1. Before starting assembly of master cylinder,
dip protector washers, seals, pistons, springs,
check valves, and retainers in alcohol and place
in clean pan or on a clean paper.
NOTE: Do not handle hydraulic system parts
with greasy hands
...
-Sw
0--
BRAKES
8-16
2. Dip two piston seals in brake fluid and install
seals on spring end of secondary piston with seals
back-to-back, Fig. 8-18. Install retainer on outer
seal.
3. Stand piston on end opposite seals and install
spring and spring retainer.
4. Insta11pring adjusting screw in bottom of
spring retainer and start screw into piston body
by exerting enough pressure on screw driver to
compress spring and engage threads.
5. Tighten spring adjusting screw until meas
urement from end of spring retainer to surface
against which protector washer seats, is 3-35/64
inches, as shown in Fig. 8-19. To measure this
distance accurately, place piston on a flat surface
with spring retainer down and, using a steel scale
graduated in sixty-fourths of an inch, measure
upward from end of retainer.
Fig. 8-20
CAUTION: If screw is turned in too far,
piston will cover master cylinder inlet port,
resulting in excessive brake pedal travel before
brakes apply. If screw is not turned in far
enough, piston will cover by-pass hole in
cylinder, and pressure build-up will
f-ister
cause brake drag.
6. Install protector washer, seal, and retainer
on end of secondary piston.
7. Coat inside bore of master cylinder with
brake fluid and dip secondary piston and seals in
brake fluid.
/
Protector
Washer Seat
Installing Piston Stop And Seal Assembly
8. Stack secondary piston assembly, secondary
spring with small diameter end of spring next to
piston, and spring stop, Fig. 8-16.
9. Insert check valve spring in recessed end of
check valve and place these parts on spring stop.
Carefully guide this group of parts into master
cylinder.
10. Dip primary piston and piston stop and seal
assembly in brake fluid and, using Master Cylin
der Shaft Seal Installer, J-97l9-Ol, Fig. 8-20, in
stall new piston stop and seal assembly over end
of primary piston with undercut end of stop toward
primary seal end of piston.
11. Install protector washer, piston seal, and
retainer on primary piston with lip of seal toward
retainer.
12. Dip entire assembly in brake fluid anduide
into position in cylinder bore. Install snap ring in
ring groove.
NOTE: Undercut on brass piston stop and
seal assembly should not be visible.
..o
C’,
Ci
13. Dip residual check valve in brake fluid. In
sert spring in recessed end of check valve and
install valve and spring in rear outlet of master
cylinder, Fig. 8-16.
.-
Fig. 8-19
-‘S
-
Spring
Retainer
Secondary Piston Spring Adjustment
14. Place new gasket on outlet fitting and install
fitting in master cylinder.
15. Install filler caps in master cylinder.
BRAKES
Fig. 8-21
8-17
Removing Delco Moraine Power Unit Rear Shell
18. Delco Moraine Power Brake Unit
Disassembly, Cleaning, Inspection
and Assembly
a. Disassembly
Fig. 8-23
Support Plate Seal Retainer Disassembled
6. Pull push rod through dust guard on rear
shell and remove air filter and retainer from
hollow tube surrounding push rod.
1. Scribe a line on top center of front and rear
shells of power unit in line with master cylinder
filler caps.
7. Remove dust guard, seal band, and power
piston bearing seal from center hole in rear shell.
Remove silencer from dust guard.
2. Place assembly in bench vise with rear shell
up and tighten vise jaws securely on master cylin
der, being careful not to crack casting.
8. Remove front shell and master cylinder from
vise and remove vacuum check valve and
grommet.
3. Install Power Unit Shell Separator, J-9504,
over mounting studs on rear shell. Apply a slight
downward pressure and rotate rear shell counter
clockwise until it disengages from front shell,
Fig. 8-21.
9. Remove two nuts and lockwashers that retain
master cylinder to front shell and remove master
cylinder.
CAUTION: Be careful when removing Sepa
rator Tool as internal piston return spring may
cause rear shell to fly off when pressure is
released.
4. Pump push rod three or four times to re
lieve residual vacuum in power unit.
5. Remove rear shell, power piston assembly,
and piston return spring, rig. 8-22.
Rear Shell
Dust
Guard
10. Remove support plate seal retainer from
center of front shell and remove seal from re
tainer, Fig. 8-23.
11. Remove gasket from O.D. of retainer.
12. With master cylinder push rod up, remove
three special hex head screws from power piston
and lift master cylinder push rod and diaphragm
support plate assembly from power piston as
sembly, Fig. 8-24.
Power Piston
Assembly
Seal
Band
Grommet
Front Shell
N
Vacuum
Check
Valve
I
Master
Cylinder
Silencer
Bearing
Seal
Piston Return
Spring
Fig. 8-22
Delco Moraine Power Unit Disassembled
Lockwasher
Support Plate
Seal Retainer
Nut
BRAKES
8-18
Power
Piston
Valve Spring
Master Cylinder
Push Rod
Plate
/
I
Reaction
Levers
Adjusting
It
i
Spring
"0" Ring
Seals
Special
Screw
Fig. 8-24
13. Remove three reaction
seats in power piston insert.
levers from their
15. Remove air valve and push rod assembly
from power piston.
and 0-ring
Silencer
Spring
Air Valve and
Push Rod Assembly
/
Air Filter
Retainer
Delco Moraine Power Piston Disassembled
14. Remove air valve spring from counterbore
of air valve.
16. Remove snubber
grooves in air valve.
Power
Piston
Insert
I
/ /..,.
I
I
Power Piston
seal
from
17. Remove power piston insert from center of
piston.
18. Remove two 0-rings from grooves in O.D.
of insert.
19. Push floating control valve assembly from
center of power piston and separate retainer, dia
phragm, and plate from control valve.
NOTE: Use of gasoline, kerosene, anti
freeze, or any other cleaner with even a trace
of mineral oil, will damage rubber parts.
2. Use air hose to blow out all passages, ori
fices, and valve holes. Air dry and place cleaned
parts on clean paper or lint-free cloth.
3. If slight rust is found inside front or rear
shell, polish clean with crocus cloth or fine emery
paper, washing clean afterwards.
4. Inspect front and rear shells for scratches,
scores, pits, dents or other damage affecting roll
ing or sealing of diaphragm or other seals. Small
imperfections may be smoothed out with fine
crocus cloth.
5. If there is any suspicion of contamination or
evidence of corrosion, completely flush car hy.
draulic system using clean brake fluid.
20. Remove floating control valve spring.
21. Remove power piston diaphragm from dia
phragm support plate.
Note position of square
diaphragm lip in relation to flange on support
plate, so that new diaphragm can be installed
properly.
CAUTION: Use care when handling power
piston diaphragm to protect it from grease, oil,
foreign material, and nicks or cuts.
22. Remove master cylinder
center of support plate.
push rod from
23. If necessary, reaction plate can be removed
by pressing plate off small knurled end of push
rod. Do not remove adjusting screw from end of
rod.
b. Cleaning and Inspection
1. Thoroughly wash all parts in clean alcohol.
6. Inspect power piston diaphragm for cuts, pin
holes, distortion or cracks.
7. Inspect all other parts for distortion, dam
age, or excessive wear and replace as necessary.
c. Assembly
Be sure all parts are clean before assembling
unit. Do not let grease or mineral oil come in
contact with any rubber parts.
Lubricate rubber parts of power piston group
with special lubricant included in service repair
kit.
1. Install power piston bearing seal in center
hole of rear shell with large flange outside, Fig.
8-22. Lubricate grooves in I.D. of bearing with
special lubricant, and install seal band over bear
ing seal.
BRAKES
8-19
2. Install silencer in dust guard and guide dust
guard over 0.D. of power piston bearing seal.
3. Install vacuum check valve in opening in
front shell using new grommet if old one is
cracked or damaged.
Floating
Control
Valve
Diaphragm
Plate
/
Floating
Valve
Diaphragm
.j
Spring
Retainer
4. Place new support plate seal in support plate
seal retainer so that flat surface of seal lies
against bottom of retainer, Fig. 8-23. Lubricate
grooves in I.D. of support plate seal with special
lubricant.
5. Place new gasket on O.D. of support plate
seal retainer and insert retainer into front shell
so that gasket is between flange on retainer and
surface of front shell, Fig. 8-22.
Fig. 8-25
Floating Control Valve Assembly Disassembled
18. Lubricate air valve 0-ring with special lu
bricant and install air valve, push rod first, into
power piston insert.
6. If previously removed, press reaction plate
over small, knurled end of master cylinder push
rod so that it lies against shoulder of push rod.
19. Install air valve spring into
end of air valve.
7. Insert master cylinder push rod through
support plate so that reaction plate lies against
support plate, Fig. 8-24.
20. Position ears of reaction levers in molded
locations in power piston insert and rest small
ends of levers on air valve spring, Fig. 8-26.
8. Rest power piston in vise with long tube
down. DO NOT CLAMP.
21. Install unfolded diaphragm on support plate
with square lip of diaphragm over support plate
flange.
9. Place floating control valve spring in center
of power piston.
10. Install floating valve diaphragm over flanged
hub of floating control valve. Flat surface of dia
phragm should be on side opposite from rubber
face of control valve, Fig. 8-25.
counterbore
22. Install diaphragm support plate assembly
on power piston making certain square lip of dia
phragm is correctly positioned between flange on
support plate and flange on edge of power piston,
Fig. 8-27.
11. Insert control valve diaphragm plate under
lip of valve diaphragm.
12. Place spring retainer
floating control valve.
down over hub of
13. Spread thin film of special lubricant on
0.D. of valve diaphragm. Install floating control
valve and diaphragm assembly in power piston,
making sure floating valve spring seats on spring
retainer, Fig. 8-24.
NOTE: Make sure that rubber diaphragm
is not distorted as the assembly is pressed
into power piston.
14. Install two power piston 0-rings in grooves
on 0.D. of power piston insert.
15. Install piston insert in power piston, being
careful not to misposition 0-rings.
16. Install air valve 0-ring into groove in 0.D.
of air valve.
17. Install air valve snubber over flanged end
of air valve.
Air Valve Spring
Fig. 8-26
Power Piston
Positioning Reaction Levers
8-20
BRAKES
30. Insert power piston, push rod first, into
rear shell of power unit. Extension on end of
power piston fits through power piston bearing
seal and push rod through silencer and dust guard.
31. Fold diaphragm back into position on rear
shell flange.
32. Install rear shell and power piston assem
bly into front shell. Align scribe marks on shells
so that when shells are rotated into locked po
sition, scribe marks will line up.
Fig. 8-27
Power Piston Diaphragm Installed in Power Unit
NOTE: When locating diaphragm support
plate on power piston, be sure reaction levers
maintain their positions in seats in power piston
insert.
23. Install three special hex head screws that
hold power piston to support plate. Torque screws
to 60 inch-pounds, Fig. 8-24.
33. Install Power Unit Shell Separator, J-9504,
over mounting studs on rear shell and press rear
shell into front shell making certain that oval lip
of diaphragm is correctly positioned between
edges of front and rear shells. Rotate rear shell
clockwise to lock shells together.
24. Install filter retainer on push rod, wrap flat
piece of filter material around push rod and press
down into power piston tube.
NOTE: Master cylinder push rod is designed
with a self-locking adjustment screw to provide
the correct relationship between vacuum piston
and master cylinder piston. This adjustment is
very important because it assures the compen
sating port being kept open while unit is in re
leased position. Adjustment screw is set to
correct height at time of assembly and, under
normal service, will not require further ad
justment.
When unit has been disassembled,
however, adjustment should be checked to as
sure proper height.
25. Install master cylinder on front shell of
power unit and install two lockwashers and nuts
finger tight, Fig. 8-22.
34. Place power brake assembly on bench with
master cylinder up and remove master cylinder
and support plate seal retainer.
26. Clamp master cylinder in vise with front
shell up.
35. Place Push Rod Height Gage, J-7723-01,
over push rod with legs of gage resting on front
shell of vacuum power unit, Fig. 8-28. Top of
screw should just touch gage.
NOTE: Press in on air valve and push rod
assembly to make certain it is under spring
tension and that reaction levers have not be
come mispositioned.
27. Install power piston return spring so that it
seats over support plate seal retainer.
28. Lightly lubricate tube extension on master
cylinder end of power piston and tube extension
on push rod end of power piston with special
lubricant.
29. Lightly cover oval lip of diaphragm with
talcum powder.
36. If adjustment is necessary, turn adjusting
screw either in or out as required.
37. Install support plate seal retainer into front
shell so that gasket is between flange on retainer
and surface of front shell, Fig. 8-22.
38. Install master cylinder on vacuum power
unit and secure with two lockwashers and nuts.
Torque to 17 foot-pounds.
19. Delco Moraine Master Cylinder
Disassembly, Cleaning, Inspection
and Assembly
a. Disassembly
Fig. 8-28
Checking Push Rod Height Delco Moraine
NOTE: If trouble has been traced to hydrau
lic system, master cylinder may be removed
from vacuum unit without removing complete
power brake assembly from car. Area sur
rounding master cylinder mounting surface must
be kept clean.
BRAKES
1. Disconnect primary and secondary
lines, if not done previously.
13. Remove primary seal, protector
and secondary seals from floating piston.
brake
washer,
14. Compress primary piston spring, attached
to primary piston, remove small retainer ring
from groove in end of piston, and remove piston
spring and floating piston stop.
2. Remove two nuts and lockwashers and re
move master cylinder from vacuum power unit.
3. Remove filter from groove on O.D. of open
end of master cylinder, Fig. 8-29.
15. Remove spring retainer, primary seal, pro
tector washer, and secondary seal from primary
piston.
4. Remove floating piston stop bolt and gasket
from boss between outlet holes on side of master
cylinder.
b. Cleaning and Inspection
5. Remove headnut and gasket from master
cylinder housing and remove floating piston spring
and retainer.
1. Thoroughly wash all parts in clean alcohol.
NoTE:
Use of gasoline, kerosene, antifreeze,
or any other cleaner with even a trace of min
eral oil will damage rubber parts.
6. Remove lock ring from open end of master
cylinder and remove primary piston assembly.
7. Push floating piston out of unthreaded rear
end of master cylinder bore.
2. Use air hose to blow out all passages, ori
fices, and valve holes. Air dry and place cleaned
parts on clean paper or lint-free cloth.
8. Remove filler caps from fluid reservoirs.
9. Place master cylinder
holes up.
8-21
3. Inspect master cylinder bore for scoring,
rust, pitting or etching. Any of these will require
replacement of master cylinder housing.
in vise with outlet
10. Install a spare brake line tube nut in outlet
hole, Fig. 8-30. Place flat washer on 1 inch i8-32
screw and thread screw into threaded hole in tube
seat insert.
4. Inspect master cylinder pistons for scoring,
pitting or distortion. Any of these will require
replacement of piston.
NOTE: If either master cylinder housing or
pistons are replaced, thoroughly clean new
parts with alcohol and blow out all passages
with air hose.
NOTE: Before installing screw, run a p8-32
tap into hole to clean up threads.
11. To pull insert, hold screw from turning and
turn tube nut out of outlet hole, Fig. 8-30. Re
move both inserts in this manner and discard.
5. Examine fluid reservoirs for foreign matter
and check all passages for restrictions. If there
is any suspicion of contamination or evidence of
corrosion, completely flush car hydraulic system
using clean brake fluid.
12. From cavity beneath each tube insert, re
move rubber check valve and check valve spring,
Fig. 8-29.
Filler Caps
Protector
Washer
Floating
Piston
Stop
Filter
Headnut
Retainer
Ring
rfi:rn
Lock
Ring
Secondary
Seal
Primary
Seal
Spring
Retainer
Primary
Piston
Spring
Floating
Piston
Protector
Washer
Floating
Piston
Spring
Gasket
0
O.
Secondary
Seals
Spring
Retainer
Primary
Secil
Tube
Seat
Insert
Fig. 8-29
Delco Moraine Master Cylinder Disassembled
Stop
Bolt
BRA K ES
8-22
on end of master cylinder piston opposite sec
ondary seal. Protector washer seats against
flange on piston that contains compensating holes
and flat side of seal seats against washer.
#8.32 Screw
Tube Nut
V
Washer
9. Position spring retainer on one end of pri
mary piston spring and floating piston stop on
other end.
10. Install primary piston spring on primary
piston with spring retainer seated inside lips of
primary seal.
11. Compress piston spring until floating piston
stop clears small groove in end of piston. Install
small retaining ring in this groove and releae
spring.
Fig. 8-30
Removing Tube Seat Insert
6. When overhauling master cylinder, use all
parts furnished in master cylinder repair kit.
c. Assembly
Be sure all parts are clean before assembling
master cylinder. Do not let grease or mineral
oil come in contact with any rubber parts.
Lubricate rubber
only.
parts with clean brake fluid
1. Place master cylinder in vise with outlet
holes up and install check valve springs in outlet
holes so that they seat in depression in bottom
of holes, Fig. 8-29.
2. Install new rubber check valves over springs,
being careful not to displace springs from their
seats. When check valve is properly seated, end
of valve will be even with machined top of outlet
boss.
3. Position new brass tube inserts in outlet
holes. Thread spare brake line tube nut into each
outlet hole and turn nuts down until inserts bottom.
4. Remove tube nuts and check both outlet holes
for loose brass burrs.
5. Install new secondary seals in grooves in
counterbored end of floating piston, back-to-back,
Fig. 8-29.
6. Install new protector washer and primary
seal over end of floating piston opposite secondary
seals. Protector washer seats against flange of
piston that contains small compensating holes,
and flat side of seal seats against washer.
7. Install primary piston secondary seal in
groove on push rod end of primary piston. Lip of
seal should face toward small compensating holes
in opposite end of piston.
8. Install protector
washer and primary seal
12. Coat master cylinder bore and primary and
secondary seals on floating piston with clean
brake fluid.
13. Insert floating piston, primary seal first,
into unthreaded rear end of master cylinder bore.
Push piston forward until end of piston is even
with beginning of threads for headnut.
14. Install floating piston stop bolt and new
gasket in side of master cylinder housing and
push floating piston rearward until it contacts
stop bolt. Tighten stop bolt to 10 foot-pounds
torque.
15. Place spring retainer on end of floating
piston spring and insert spring into threaded end
of master cylinder bore with retainer seated in
side lips of floating piston primary seal.
16. Place new copper gasket on headnut and
install headnut in master cylinder, being careful
to seat floating piston spring in counterbore of
headnut. Tighten to 105 foot-pounds torque.
17. Coat primary and secondary seals on pri
mary piston with clean brake fluid and insert
piston into master cylinder bore, spring end first.
18. Install lock ring in groove in master cyl
inder bore.
19. Install new filter element in groove on 0.D.
of master cylinder.
20. Install reservoir filler caps.
20. Brake System Testing
1. With engine running at idle and transmission
in neutral, depress brake pedal and hold foot pres
sure on pedal. If pedal gradually falls away under
foot pressure, hydraulic system is leaking.
2. If hydraulic system is not leaking, but pedal
travels more than two inches, brake shoe adjusters
BRAKES
are not functioning qr shoes require relining. If
pedal has a spongy feel, air may be present in
hydraulic system. Bleed system as described
in Note 9.
8-23
4. With vacuum depleted from system, depress
brake pedal, hold light foot pressure on pedal,
and start engine. If vacuum system is operating,
pedal will tend to fall away under foot pressure,
and less pressure will be required to hold pedal
in applied position. If no action is felt, vacuum
system is not functioning.
3. With brakes off, operate engine at medium
speed, then back to idle and turn off ignition. Wait
at least two minutes, then try brake action. If not
vacuum assiste,d for two or more applications,
vacuum check valve is faulty or there is a leak
in vacuum system.
5. Road test brakes by making a brake applica
tion at various speeds up to 50 mph to determine
if car stops evenly and effectively.
DIAGNOSIS CHART
CONDITION
Brake pedal goes down to toeboard or drops off about half
the distance from its normal
position.
CORRECTION
CAUSE
Uneven wear on linings.
Replace shoe and linings.
No fluid in reservoir.
Add fluid, inspect for leakage,
and bleed system.
Leaking
line.
Tighten or replace.
front or rear brake
Air in brake system which
causes a rubbery action of
brake pedal.
system.
Check for
Bleed
shrunken or swollen wheel cyl
inder piston cups, and if noted
replace and correct cause.
Check residual check valves
and replace if faulty.
Wheel cylinder piston cups
swollen by mineral oil in sys
tem, or sub- standard brake
fluid.
Disassemble
all hydraulic
parts and wash with alcohol.
Dry with compressed air be
fore assembly to keep alcohol
out of system.
Replace all rubber parts in
system, including hoses.
Replace brake shoe assemblies
or linings if glazed by brake
fluid leakage.
Refill with heavy duty brake
fluid and bleed system.
Leaking master cylinder piston
cups.
Replace.
Disconnected unit linkage.
Connect.
Cracked. master cylinder casting.
Replace.
Adjusters sticky.
Lubricate.
Brake shoes
justed.
improperly ad
Check automatic adjusters and
make necessary adjustments.
Leak at master cylinder headnut.
Install new copper gasket and
torque headnut to 105 foot
pounds.
BRAKES
8-24
DIAGNOSIS CHART CONT’D.
CAUSE
CONDITION
No pedal after hard usage.
Excessive heat causes fluid to
vaporize.
CORRECTION
Check parking brake adjust
ment and make corrections as
required.
Determine whether one or more
wheels are dragging and heat
ing, and correct.
Check proximity of any brake
pipe to the engine exhaust sys
tem and correct.
Be sure car is using heavy
duty brake fluid. If in doubt,
drain, flush and refill.
Hard pedal.
Car pulls to one side when
brakes are applied.
Faulty vacuum check valve.
Replace.
Collapsed vacuum hose.
Replace or correct.
Plugged vacuum hose or fittings.
Clean or replace.
Leaking
line.
Repair or replace.
front or rear brake
Pedal mechanism binding.
Repair.
Restricted air filter.
Clean.
Vacuum leak in unit.
Repair or replace.
Defective rolling diaphragm.
Replace.
Lining glazed due to light traffic use,
Resurface lining with medium
sandpaper.
Incorrect linings used.
Replace brake shoes or install
new linings.
Front wheel
misadjusted.
Correct as required until car
has no "lead" without brakes
applied.
caster-camber
Weak or improperly installed
shoe retracting springs,
Replace retracting springs as
required.
Oil or brake fluid on linings.
Replace brake shoe assemblies
or install
new linings. Oil
soaked linings cannot be clean
ed and used again successfully.
Also correct condition which
caused
linings
to become
soaked.
Lining surface contaminated or
slightly
charred
from fast
break- in.
Sand lining surface.
Different makes of linings used
between left and right sides,
Different makes of lining have
different braking efficiency.
Replace brake shoes or install
new linings on both sides.
One wheel drags.
Make corrections to brakes as
required.
-
BRAKES
8-25
DIAGNOSIS CHART CONT D.
CONDITION
Car pulls to one side when
brakes are applied. Cont’d.
Brakes drag at all wheels.
Springy pedal action.
CORRECTION
CAUSE
Scored brake drums.
Machine left and right brake
drums or replace both if more
than .030 inch radius has to be
removed.
Drums have different friction
between left and right sides,
Visual inspection will show ap
preciable
difference
in
porosity.
Machine both drums and sand
linings or replace as required.
Compensating ports in master
cylinder reservoir not opening,
Clean or check for full pedal
return. Check vacuum piston
to hydraulic piston push rod
for correct adjustment.
Brake pedal return travel restricted,,
Check for obstruction or bind
ing.
Air in brake system.
Bleed system.
Investigate and correct cause
of air being drawn into system.
Brake shoes
justed.
improperly ad-
Correct malfunction of auto
matic adjusters as required.
Improper fit of new lining to
brake drums.
Install shoe and lining assem
blies which are ground to fit.
Follow break-in procedure for
new linings.
Linings damaged by excessive
heat.
Replace shoe and linings.
Oil or fluid on linings.
Replace brake shoe assemblies
or install new linings. Linings
cannot be cleaned and used
again
successfully.
Correct
leaks.
Squeaking during application or
release,
Insufficient lubricant at brake
shoe guide pads.
Apply special heat resistant
lubricant as required.
Brake squeal or squeak during
stop.
Lining making poor contact
with drum excessive edge contact.
Check wear pattern. Sand or
file to produce more uniform
contact.
.
Too light pedal pressure brake
action severe,
If lining is new, follow breakin procedure.
Steel washer on "star wheel"
bent, broken, or missing.
Replace steel washer.
Insufficient shoe retention.
Inspect shoe stabilizer plates
for proper installation and
spring tension.
BRAKES
8-26
DIAGNOSIS CHART CONT’D.
CONDITION
CAUSE
CORRECTION
Brake moan during stop.
Drum vibration.
Install proper type drum-towheel clip kit.
Brakes slow or fail to release.
Dirty compensating port.
Clean.
Bent or dented vacuum cylinder.
Replace.
Restricted air passage in power
piston.
Remove or replace.
Broken vacuum piston return
spring.
Replace.
Faulty hydraulic check valves.
Replace.
Air valve sticking.
Clean or replace.
Tight pedal linkage.
Repair.
SPECIFICATIONS
All Series
Unless Otherwise Noted
Item
Braking Area total in square inches
60 and 62 series cars
75 series and Commercial Chassis
245.2
260.0
Braking Ratio inside diameter
Front - 60, 62, and 75 series cars
Rear - 60, 62 and 75 series cars
Front - Commercial Chassis
Rear - Commercial Chassis
59.0%
41.0%
52.8%
47.2%
Drums inside diameter
Front and Rear
ll.995"-l2.005"
Run-out of Inside Diameter maximum
Front and Rear
007"
Clearance Between Secondary Lining and Drums
Minimum
Maximum
030"
Remachined diameter maximum
12.060"
Primary Lining length, width, thickness
Front and Rear
60 and 62 series cars
Front and Rear - 75 series and Commercial Chassis
11.52 x 2.50 x .254
12.98 x 2.50 x .274
Secondary Lining length, width, thickness
Front and Rear - 60 and 62 series cars
Front and Rear - 75 series and Commercial Chassis
12.98 x 2.50 x .254
12.98 x 2.50 x .274
-
Lining To Shoe Attachment Method
Wheel Cylinder Bore
Front
Rear - 60, 62 and 75 series
Rear - Commercial Chassis
Rivets
1-3/16"
1"
1-1/8"
BRAKES
8-27
A
Fig. 8-31
Special Tools
Name
Tool No.
Key
Name
Key
Tool No.
A
J-9504
Power Unit Shell
Separator
D
J-9719-Ol
Master Cylinder Shaft
Seal Installer
B
J-8049
Brake Spring Remover
and Installer
E
J-7723-Ol
Push Rod Height Gage
C
None
Special Parking Brake
Gage
F
J-9540
Bearing Seal Installer
TORQUE SPECIFICATIONS
Material
No.
Spec.
Applicaition
Size
Brake fluid line connections
Special
Foot-Pounds
8
260M
Parking brake cable clamps at backing plate
5/16-24
11
300M
Front backing plate to knuckle
1/2-20
65
300M
Brake backing plate to rear axle housing
except Commercial Chassis
3/8-24
40
300M
Brake backing plate to rear axle housing
Commercial Chassis
7/16-20
70
300M
Front brake anchor pin to knuckle
9/16-18
100
284M
Brake unit to cowl
3/8-24
20
286M
Master cylinder to vacuum power unit
3/8-24
17
286M
Power piston to support plate screws
1/4-14
Special
Head Nut Master Cylinder
Special
Floating Piston Stop Bolt
NOTE: Refer to back of manual, Page
[7- 1,
60 inch lbs.
1-3/32-18
105
5/16-18
10
for bolt and nut markings and steel Classifications.
7
V
PARK AVENUE SEDAN
6389