lock CHEVROLET PLYMOUTH ACCLAIM 1993 Workshop Manual

SERVICE ADJUSTMENTS INDEX
page page
Adjusting Rear Service Brakes ............... 4
Bleeding Brake System ..................... 6
Brake Hose and Tubing ................... 11
Master Cylinder Fluid Level .................. 4 Stop Lamp Switch Adjustment (All Vehicles)
.... 13
Test for Fluid Contamination ................. 7
Testing Application Adjuster Operation ......... 6
Wheel Stud Nut Tightening .................. 7
MASTER CYLINDER FLUID LEVEL
ALL EXCEPT AC/AY BODY WITH ABS
Check master cylinder reservoir brake fluid level a
minimum of twice a year. Master cylinder reservoirs are marked with the
words fill to bottom of rings indicating proper fluid
level (Fig. 1). If necessary, add fluid to bring the level to the bot-
tom of the primary reservoir split ring. Use only Mopar tbrake fluid or an equivalent from
a sealed container. Brake fluid must conform to DOT
3, specifications. DO NOT use brake fluid with a lower boiling
point, as brake failure could result during prolonged
hard braking. Use only brake fluid that was stored in a tightly-
sealed container. DO NOT use petroleum-based fluid because seal
damage in the brake system will result.
AC AND AY BODY WITH ANTI-LOCK BRAKES
The hydraulic assembly is equipped with a plastic
fluid reservoir with a filter/strainer in the filler neck
of the reservoir. The Anti-Lock brake system requires that the hy-
draulic accumulator be de-pressurized whenever
checking the brake fluid level. To check the brake
fluid level, the following procedure should be used: (1) With the ignition switch turned to the off position
and key removed. De-pressurize hydraulic accumula-
tor by applying brake pedal approximately 40 times,
using a pedal force of approximately 220 N (50 lbs.). A
noticeable change in pedal feel will occur when accu-
mulator is de-pressurized. Continue to apply brake
pedal several times after this change in pedal feel
occurs to insure that brake system is fully de-
pressurized. (2) Thoroughly clean both reservoir caps and sur-
rounding area of reservoir, (Fig. 2) before removing
caps. This is to avoid getting dirt into the reservoir and
contaminating the brake fluid. (3) Inspect the brake fluid to see if it is at the proper
level, see instructions on top of reservoir. (FILL TO
TOP OF WHITE SCREEN ON FRONT
FILTER/STRAINER.) (4) Fill reservoir with brake fluid to top of screen
(Fig. 3) on the filter/strainer located in brake fluid
reservoir. Only use brake fluid conforming to DOT 3
specifications such as Mopar tor equivalent.
(5) Replace brake fluid reservoir caps.
ADJUSTING REAR SERVICE BRAKES
Normally, self adjusting drum brakes will not
require manual brake shoe adjustment. Al-
though in the event of a brake reline it is advis-
able to make the initial adjustment manually to
speed up the adjusting time. (1) Raise the vehicle so all wheels are free to turn.
See Hoisting Recommendations in the Lubrication And
Maintenance Section, at the front of this service
manual. (2) Remove rear brake adjusting hole rubber plug
(Fig. 4), from the rear brake shoe support plate. (3) Be sure parking brake lever is fully re-
leased. Then back off parking brake cable adjust-
ment so there is slack in the cable. (4) Insert Brake Adjuster, Special Tool C-3784, (Fig.
5) or equivalent through the adjusting hole in support
plate and against star wheel of adjusting screw. Move
handle of tool upward until a slight drag is felt when
the road wheel is rotated. (5) Insert a thin screwdriver or piece of welding rod
into brake adjusting hole (Fig. 5). Push adjusting lever
out of engagement with star wheel. Care
Fig. 1 Master Cylinder Fluid Level (All Except AC/AY
Body W/ABS)
5 - 4 BRAKES Ä

TESTING APPLICATION ADJUSTER OPERATION
Place the vehicle on a hoist with a helper in the
driver's seat to apply the brakes. Remove the access
plug from the rear adjustment slot in each brake
support plate (Fig. 4) to provide access to the ad-
juster star wheel. Then, to eliminate the possibility
of maximum adjustment, where the adjuster does not
operate because the closest possible adjustment has
been reached. Back the star wheel off approximately
30 notches. It will be necessary to hold the adjuster
lever away from the star wheel to permit this adjust-
ment. Spin the wheel and brake drum in the reverse di-
rection, and with a greater than normal force apply
the brakes suddenly. This sudden application of force
will cause the secondary brake shoe to leave the an-
chor. The wrap up effect will move the secondary
shoe, and the cable will pull the adjuster lever up.
Upon application of the brake pedal, the lever should
move upward, turning the star wheel. Thus, a defi-
nite rotation of the adjuster star wheel can be ob-
served if the automatic adjuster is working properly.
If one or more adjusters do not function properly, the
respective drum must be removed for adjuster servic-
ing.
BLEEDING BRAKE SYSTEM
CAUTION: For bleeding of the Anti-Lock brake hy-
draulic system. See the Anti-Lock Brake system
service procedures in this group which refers to the
particular Anti-Lock brake system being serviced.
PRESSURE BLEEDING
Before removing the master cylinder cover, wipe it
clean to prevent dirt and other foreign matter from
dropping into the master cylinder. CAUTION: Use bleeder tank Special Tool C-3496-B
with adapter Special Tool C-4578 to pressurize the
system for bleeding.
Follow pressure bleeder manufacturer's instruc-
tions, for use of pressure bleeding equipment. When bleeding the brake system. Some air may be
trapped in the brake lines or valves far upstream. As
much as ten feet from the bleeder screw (Fig. 6).
Therefore, it is essential to have a fast flow of a large
volume of brake fluid when bleeding the brakes to
ensure all the air gets out.
The following wheel sequence for bleeding the
brake hydraulic system should be used to ensure ad-
equate removal of all trapped air from the hydraulic
system.
² Right rear wheel
² Left front wheel
² Left rear wheel
² Right front wheel
To bleed the brake system. Attach a clear plastic
hose to the bleeder screw starting at the right rear
wheel and feed the hose into a clear jar containing
fresh brake fluid (Fig. 7). Next, open the bleeder screw at least one full turn
or more to obtain an adequate flow of brake fluid
(Fig. 8).
CAUTION: Just cracking the bleeder screw often re-
stricts fluid flow, and a slow, weak fluid discharge
will NOT get all the air out.
After 4 to 8 ounces of fluid has been bled through
the brake system at this wheel. And an air-free flow
is maintained in the clear plastic hose and jar, this
will indicate a good bleed. Repeat the procedure at all the other remaining
bleeder screws. Then check the pedal for travel. If
pedal travel is excessive or has not been improved.
Enough fluid has not passed through the system to
Fig. 5 Brake Drum Adjustment With Tool C-3784
Fig. 6 Trapped Air in Brake Line
5 - 6 BRAKES Ä

FIG. 11 BRAKE LINE ROUTING WITH ANTI-LOCK 10 BRAKES
Ä BRAKES 5 - 9

FIG. 12 BRAKE LINE ROUTING WITH ANTI-LOCK 6 BRAKES
5 - 10 BRAKES Ä

ing inserted in jaws but do not apply heavy pressure
to handle as this will lock tubing in place.Place gauge (Form A) on edge over end of brake
tubing. Push tubing through jaws until end of tubing
contacts the recessed notch in gauge matching the
tubing size. Squeeze handles of flaring tool and lock
tubing in place. Place 3/16 inch plug of gauge (A)
down in end of tubing. Swing compression disc over
gauge and center tapered flaring screw in recess of
disc. Screw in until plug gauge has seated on jaws of
flaring tool. This action has started to invert the ex- tended end of the tubing. Remove gauge and continue
to screw down until tool is firmly seated in tubing.
Remove tubing from flaring tool and inspect seat. Refer
to routing diagrams (Figs. 18 to 21) for proper routing
and clip location. Replace any damaged tube routing
clips.
ISO TUBING FLARES
CAUTION: All ISO style tubing flares (Fig. 13 & 16 ) are
of metric dimensions. When performing any service
procedures on vehicles using ISO style tubing flares,
metric size tubing of 4.75 mm MUST be used with
metric ISO tube flaring equipment.
To create a (metric) ISO style tubing flare, Use
Snap-On Flaring Tool TFM-428, or equivalent. See
(Fig. 17) and proceed with the steps listed below. Be
sure to place the tubing nut on the tube before
flaring the tubing. (1) Carefully prepare the end of the tubing to be
flared. Be sure the end of the tubing to be flared is
square and all burrs on the inside of the tubing are
removed (Fig. 15). This preparation is essential to
obtain the correct form of a (metric) ISO tubing
flare. (2) Open the jaws of the Flaring Tool. Align the
mating size jaws of the flaring tool around the size of
the tubing to be flared. Close the jaws of the Flaring
Tool around the tubing to keep it from sliding out of the
flaring tool, but do not lock the tubing in place. See
(Fig. 17)
Fig. 14 Cutting and Flaring of Brake Line Tubing
Fig. 15 Brake Tube Preparation For Flaring
Fig. 16 Double Flare And ISO-Flare Tubing Connec- tions
5 - 12 BRAKES Ä

REAR WHEEL DRUM BRAKES INDEX
page page
Brake Drum Refacing ..................... 21
Brake Shoe Assemblies ................... 19 Description
............................. 18
Service Procedures ....................... 18
DESCRIPTION
Rear wheel drum brakes (Fig .2&3)aretwoshoe,
internal expanding type with an automatic adjuster
screw assembly that is activated each time the
brakes are applied. The automatic adjuster screw is
located directly below the wheel cylinder as shown in
figure (Fig .2&3).
WARNING: DUST AND DIRT ON BRAKE PARTS
GENERATED DURING THE NORMAL USE AND
WEAR OF MOTOR VEHICLE BRAKE SYSTEMS MAY
CONTAIN ASBESTOS FIBERS. BREATHING EXCES-
SIVE CONCENTRATIONS OF ASBESTOS FIBERS
CAN CAUSE SERIOUS BODILY HARM, SUCH AS
ASBESTOSIS AND CANCER. EXTREME CARE
SHOULD BE EXERCISED WHILE SERVICING
BRAKE ASSEMBLIES OR COMPONENTS. DO NOT CLEAN BRAKE ASSEMBLIES OR COM-
PONENTS WITH COMPRESSED AIR OR BY DRY
BRUSHING; USE A VACUUM CLEANER SPECIFI-
CALLY RECOMMENDED FOR USE WITH ASBES-
TOS FIBERS. IF A SUITABLE VACUUM CLEANER IS
NOT AVAILABLE, CLEANING SHOULD BE DONE
WET USING A WATER DAMPENED CLOTH. DO NOT CREATE DUST BY SANDING, GRINDING,
AND/OR SHAVING BRAKE LININGS OR PADS UN-
LESS SUCH OPERATION IS DONE WHILE USING
PROPERLY EXHAUST VENTILATED EQUIPMENT. DISPOSE OF ALL DUST AND DIRT SUSPECTED
TO CONTAIN ANY ASBESTOS FIBERS IN SEALED
BAGS OR CONTAINERS TO MINIMIZE DUST EXPO-
SURE TO YOURSELF AND OTHERS. FOLLOW ALL RECOMMENDED PRACTICES PRE-
SCRIBED BY THE OCCUPATIONAL SAFETY AND
HEALTH ADMINISTRATION AND THE ENVIRON-
MENTAL PROTECTION AGENCY. FOR THE HAN-
DLING, PROCESSING, AND DISPOSITION OF DUST
OR DIRT WHICH MAY CONTAIN ASBESTOS FI-
BERS. IT IS RECOMMENDED NOT TO BREATH ANY
TYPE OF BRAKE LINING MATERIAL DUST EVEN
ASBESTOS FREE, DUE TO THE FIBROUS NATURE
OF THE MATERIALS BEING USED.
SERVICE PROCEDURES
REAR BRAKE DRUM REMOVAL
If the rear brake drum is difficult to remove, fur-
ther clearance can be obtained by backing off the
brake automatic adjuster screw. Remove rubber plug
from the top of the support plate and rotate the au-
tomatic adjuster screw assembly with an upward mo-
tion, using the Brake Adjuster, Special Tool C-3784. See adjusting rear service brakes in the Service
Adjustments section in this group of the service man-
ual for the specific adjustment procedure. Remove wheel bearing grease cap (Fig. 1).
Remove cotter pin, nut lock, retaining nut, thrust
washer and outer bearing cone (Fig. 1). Remove brake drum and hub and bearing assembly
from the rear spindle (Fig. 1). Inspect brake linings for wear, shoe alignment and
contamination.
BRAKE DRUM INSTALLATION
Install brake drum and hub and bearing assembly
on rear spindle. Install outer wheel bearing, thrust washer and nut.
Tighten wheel bearing adjusting nut to 27 to 34
N Im (240 to 300 in. lbs.) torque while rotating hub.
This seats the bearings. Back off adjusting nut 1/4 turn (90É) then tighten
adjusting nut finger tight. Position lock on nut with one pair of slots in-line
with cotter pin hole. Install cotter pin.
Fig. 1 Brake Drum and Hub Assembly
5 - 18 BRAKES Ä

WHEEL CYLINDERS INDEX
page page
General Information ....................... 23
Installing Wheel Cylinders .................. 24 Service Procedures
....................... 23
GENERAL INFORMATION
The piston boots are of the push-on type and pre-
vent moisture from entering the wheel cylinder. To perform service operations or inspections of the
rear wheel brake cylinders. It will be necessary to re-
move the cylinders from the support plate and disas-
semble on the bench.
CAUTION: Wheel cylinders with cup expanders
must have cup expanders after any service proce-
dures (reconditioning or replacement).
SERVICE PROCEDURES
REMOVING WHEEL CYLINDERS FROM BRAKE SUPPORT PLATES
With brake drums removed, inspect the wheel cyl-
inder boots for evidence of a brake fluid leak. Then
block the brake pedal in the stroke position, and vi-
sually check the boots for cuts, tears, or heat cracks.
If any of these conditions exist, the wheel cylinders
should be completely cleaned, inspected and new
parts installed. (A slight amount of fluid on the boot
may not be a leak, but may be preservative fluid
used at assembly.) (1) In case of a leak, remove brake shoes, (replace
if soaked with grease or brake fluid.) (2) Thoroughly clean area of wheel cylinder, where
hydraulic brake line connects to wheel cylinder. Dis-
connect hydraulic brake tube from wheel cylinder
(Fig. 1). (3) Remove the rear wheel cylinder attaching bolts
(Fig. 1). Then pull wheel cylinder assembly off the
brake support plate (Fig. 2). (4) Clean the surface sealant off the support plate
and wheel cylinder surfaces.
DISASSEMBLING WHEEL CYLINDERS
To disassemble the wheel cylinders, (Fig. 3) pro-
ceed as follows: (1) Pry boots away from cylinders and remove.
(2) Press INon one piston to force out opposite pis-
ton, cup and spring (with cup expanders). Then using
a soft tool such as a dowel rod, press out the cup and
piston that remain in the wheel cylinder. (3) Wash wheel cylinder, pistons, and spring in
clean brake fluid or alcohol; (DO NOT USE ANY
PETROLEUM BASE SOLVENTS) clean thor- oughly and blow dry with compressed air. Inspect
Fig. 1 Brake Tube Disconnected
Fig. 2 Remove or Install Wheel Cylinder
Ä
BRAKES 5 - 23

HYDRAULIC SYSTEM CONTROL VALVES INDEX
page page
ABS Brake Proportioning Valve Operation ...... 27
General Information ....................... 26
Hydraulic System Service Procedures ......... 27 Non-ABS Proportioning Unit Operation
........ 26
Pressure Differential Warning Light Switch ...... 26
Testing ABS Proportioning Valves ............ 29
GENERAL INFORMATION
Most models not equipped with an Anti-Lock brak-
ing system have a combination hydraulic system con-
trol valve in the brake hydraulic system (Fig. 1). The
valve is attached to the frame rail below the master
cylinder.
The control valve assembly combines a warning
switch with a dual proportioning valve (Fig. 2) Proportioning valves balance front to rear braking
by controlling at a given ratio, the increase in rear
system hydraulic pressure above a preset level. Un-
der light pedal application, the valve allows full hy-
draulic pressure to the rear brakes. There is only one valve assembly in each vehicle,
see Valve Application Chart. During any service pro-
cedures identify valve assemblies by part number as
well as split point (PSI) and slope.
PRESSURE DIFFERENTIAL WARNING LIGHT
SWITCH
The hydraulic brake system, on non-ABS vehicles,
is split diagonally. The left front and right rear
brakes are part of one system. And the right front and left rear are part of another. Both systems are
routed through, but hydraulically separated by a Pres-
sure Differential Switch. The function of the Pressure
Differential Switch is to alert the driver of a malfunc-
tion in the brake system. If hydraulic pressure is lost in one system, the
warning light switch will activate a red light on the
instrument panel, when the brake pedal is depressed.
At this point the brakes require service. However, since
the brake systems are split diagonally the vehicle will
retain 50% of its stopping capability in the event of a
failure in either half. The warning light switch is the latching type. It
will automatically center itself after the repair is
made and the brake pedal is depressed. The instrument panel bulb can be checked each time
the ignition switch is turned to the start position or the
parking brake is set.
NON-ABS PROPORTIONING UNIT OPERATION
The proportioning valve section operates by trans-
mitting full input pressure to the rear brakes up to a
certain point. This is called the split point. Beyond this
point it reduces the amount of pressure increase to the
rear brakes according to a certain ratio. On light pedal applications equal brake pressure will
be transmitted to the front and rear brakes. On heavier
pedal applications the pressure transmitted
Fig. 1 Brake Combination Valve And Warning Switch Location
Fig. 2 Switch and Valve Assembly
5 - 26 BRAKES Ä

to the rear will be lower than the front brakes. This will
prevent premature rear wheel lock-up and skid. If
hydraulic pressure is lost in one half of the diagonally
split system, the operation of the proportioning valve
in the remaining half is not effected.
ABS BRAKE PROPORTIONING VALVE OPERATION
On vehicles using the ABS braking system, screw in
proportioning valves are used in place of the conven-
tional differential pressure/proportioning valve. Each rear brake circuit has its own screw-in propor-
tioning valve which is attached to the rear brake outlet
ports of the hydraulic assembly. These valves limit
brake pressure to the rear brakes after a certain
pressure is reached. This improves front to rear brake
balance during normal braking.
Screw in proportioning valves can be identified by
the numbers stamped on the body of the valve. The
first digit represents the slope, the second digit repre-
sents the split (cut-in) point, and the arrow represents
the flow direction of the valve. Be sure that the
numbers listed on the replacement valve are the
same as on the valve that is being removed. See
(Fig. 3) for detail of the valve identification.
HYDRAULIC SYSTEM SERVICE PROCEDURES
BRAKE WARNING SYSTEM
CHECKING BRAKE WARNING SWITCH UNIT
The Red Brake Warning light will come on when
the parking brake is applied with the ignition key
turned ON. The same light will also illuminate
should one of the two service brake hydraulic sys-
tems fail.
CAUTION:Make sure air does not enter the hydrau-
lic system during this test procedure. See bleeding
without a pressure bleeder at the beginning of this
section for master cylinder fluid level checking pro-
cedures.
To test the service brake warning system lamp.
Raise the vehicle on a hoist and open a wheel cylin-
der bleeder while a helper depresses the brake pedal
and observes the warning light. If the light fails to light, inspect for a burned out
bulb, disconnected socket, or a broken or discon-
nected wire at the switch. If the bulb is not burned
out and the wire continuity is uninterrupted. Check
the service brake warning switch operation with a
test lamp between the switch terminal and a known
good ground. Be sure to fill master cylinder and
bleed brake system after correction has been made, if
necessary.
PROPORTIONING VALVES
TESTING PROPORTIONING VALVE UNIT
If premature rear wheel skid occurs on hard brake
application, it could be an indication that a malfunc-
tion has occurred with the proportioning valve unit. The proportioning valve is designed with two sep-
arate systems. One half controls the right rear
brake, and the other half controls the left rear brake.
Therefore, a road test to determine which rear brake
slides first is essential.
RIGHT REAR WHEEL SLIDES FIRST To test the proportioning valve when the right rear
wheel slides first, leave the front brakes connected to
the valve, proceed as follows: (1) Install one gauge and (TEE) of set C-4007-A
between the brake line from the master cylinder sec-
ondary port and the brake valve assembly. (2) Install the second gauge of set C-4007-A to the
right rear brake outlet port (Fig. 4). Using an
adapter tube, made from a short piece of brake tube
and (2) 3/8 x 24 tube nuts. Connect the hose to the
valve. Bleed the hose and gauge. (3) Have a helper exert pressure on the brake
pedal (holding pressure) to get a reading on the valve
inlet gauge and check the reading on the outlet
Fig. 3 ABS PROPORTIONING VALVE IDENTIFICA- TION
Ä BRAKES 5 - 27

WARNING: THE SELF ADJUSTING FEATURE OF THIS
PARKING BRAKE LEVER ASSEMBLY CONTAINS A
CLOCK SPRING LOADED TO APPROXIMATELY 30
POUNDS. CARE MUST BE TAKEN TO PREVENT EX-
CESSIVE JARRING OF THE ASSEMBLY. DO NOT
RELEASE THE SELF ADJUSTER LOCKOUT DEVICE
BEFORE INSTALLING CABLES INTO THE EQUAL-
IZER. KEEP HANDS OUT OF SELF ADJUSTER SEC-
TOR AND PAWL AREA. FAILURE TO OBSERVE CAU-
TION IN HANDLING THIS MECHANISM COULD LEAD
TO SERIOUS INJURY.
When repairs to the hand lever assembly or cable
system are required the self adjuster must be reloaded
and locked out.
SELF ADJUSTING PROCEDURES (AG & AJ BODY)
TO RELOAD SELF ADJUSTER
(1) Remove ash receiver or courtesy light from rear
of center console to gain access to self adjuster. Also,
remove carpet from sides of console. (2) Pull on equalizer/output cable to wind up sprin-
g(requires greater than 30 pounds effort). Continue
until self adjuster lockout pawl is positioned about
midway on the self adjuster sector (Fig. 6). Rotate
lockout pawl into self adjuster sector by turning allen
screw clockwise. Rotating lockout device requires
very little effort. Do not force or failure of lock-
out device will occur. (3) When repairs are complete, adjust rear brakes
before adjusting parking brake. On drum-in-hat type of
rear disc brake adjust shoe diameter to 171.5 mm (6.75
inch).
ADJUST PARKING BRAKE (AG & AJ BODY)
Be sure that the cables are properly assembled to the
equalizer bracket prior to cable adjustment. (1) Insert a 7/32 inch allen wrench into hex socket
and turn counter-clockwise through approximately 15É
of rotation (Fig. 4). In turning lockout device, self
adjuster release is a loud snapping noise followed by
reaching a more felt than heard detent. Very light
effort is required to seat lockout arm into detent.
Follow through to the detent is important in prevent-
ing the lockout rod from rattling. Note: The parking brake handle can be in any
position when releasing self adjuster. (2) Cycle lever to position cables. Rear wheels should
rotate freely without dragging.
REAR PARKING BRAKE CABLE REMOVAL (AA, AC,
AP, AY BODY)
The rear brake cables are attached to rear connec-
tors. Should it become necessary to remove either parking
brake cable for installation of a new cable, proceed as
follows: With vehicle jacked up on a suitable hoist, remove
wheel and tire assembly (Fig. 6). Back off cable adjusting nut to provide slack and
disconnect rear brake cable from connector.
DRUM BRAKES
(1) Disconnect park brake cable from park brake
lever in rear wheel brakes. (2) Using an aircraft type hose clamp compress re-
tainers on end of cable housing and start cable out of
retaining hole in the support plate. Remove clamp
when retainers are free of the mounting hole in the
support plate, (Fig. 6).
(3) Remove clip from brake cable at support
bracket and pull cable away from trailing arm as-
sembly (Figs. 3 and 4).
DISC BRAKES
(1) Remove disc brake caliper from adapter, and
brake disc (rotor) from rear hub.
Fig. 5 Self Adjusting Parking Brake Lever Assembly
Fig. 6 Removing Brake Cable from Support Plate
Ä BRAKES 5 - 61