1993 CHEVROLET DYNASTY oil

to the road surface. While being able to twist as one
wheel moves vertically with respect to the other.Roll resistance is provided partly by the axle's re-
sistance to twist. But primarily by a torque tube or
rod (depending on the suspension option called for)
running through the channel and attached rigidly to
its end plates by welding. Because the torque tube/
rod is an integral part of the axle assembly, it cannot
be individually replaced. The spindles are bolted to the axle end (spindle
mounting) plates and can be individually replaced if
required. Rear wheel alignment changes require the
use of shims between the spindle and axle end plates.
SHOCK ABSORBERS
REMOVAL
(1) Raise vehicle, see Hoisting, Group 0.
(2) Support axle and remove wheel and tire assem-
bly. (3) If equipped with air shocks, disconnect air
lines. (4) Remove upper and lower shock absorber fasten-
ers, remove shock absorbers (Fig. 2).
INSPECTION
Inspect for evidence of fluid leakage from upper
end of reservoir. (Actual leakage will be a stream of
fluid running down and leaking off lower end). Slight
seepage is not unusual and will not effect perfor-
mance.
INSTALLATION
(1) Position shock absorber on car. Install upper
and lower fasteners loosely to hold shock absorber in
place. (2) Tighten upper fastener to 61 N Im (45 ft. lbs.)
torque. Connect air line, if so equipped. (3) Install wheel and tire assembly, tighten wheel
stud nuts to 129 N Im (95 ft. lbs.) torque. Lower vehi-
cle to ground. (4) With suspension supporting the weight of the
vehicle. Tighten lower shock absorber fastener to 54
N Im (40 ft. lbs.) torque.
COIL SPRINGS AND JOUNCE BUMPER
REMOVAL
(1) Lift vehicle see hoisting Group 0.
(2) Support axle assembly and remove both lower
shock absorber attaching bolts. (3) Lower axle assembly until spring and spring
upper isolator can be removed (Fig. 3). Do not
stretch brake hose. (4) Remove two screws holding cup to rail (Fig. 1).
Remove assembly.
INSTALLATION
(1) Position cup to rail. Install and tighten attach-
ing bolts to 8 N Im (70 in. lbs.) torque.
(2) Install isolator over jounce bumper and install
spring. (3) Raise axle and loosely assemble both shock ab-
sorber to axle mounting bolts. Remove axle support
and lower vehicle. (4) With suspension supporting the weight of the
vehicle. Tighten both shock absorber attaching bolts
to 61 N Im (45 ft. lbs.) torque.
Fig. 2 Remove/Install Shock Absorber Fasteners
Fig. 3 Coil Spring & Jounce Bumper
Ä SUSPENSION AND DRIVESHAFTS 2 - 51

WARNING: WHEN REMOVING THE REAR AXLE
PIVOT BUSHING ON VEHICLES EQUIPPED WITH EI-
THER REAR COIL SPRINGS OR AIR SUSPENSION.
THE REAR AXLE MUST BE SUPPORTED BY THE
AXLE AND TRAILING ARM TO ENSURE ADEQUATE
SUPPORT OF REAR AXLE.
(3) Support the rear axle assembly at both the axle
channel and the trailing arm (Fig. 6). Then remove
lower shock absorber to rear axle mounting bolt (Fig.
6).
(4) Remove hanger bracket to frame rail bolts (Fig.
7).
(5) Lower axle assembly down enough to remove
pivot bolt and hanger bracket (Fig. 7). Right side
trailing arm shown.
PIVOT BUSHING REMOVAL FROM AXLE AS- SEMBLY
Remove bushing with Remover/Installer Spe-
cial Tool C-4212-L (Press) and 3 piece set, Spe- cial Tool 6122 (Receiver Support Bridge, Bushing
Remover/Installer and Bushing Remover). (1) Install receiver (support) bridge into base of
press C-4212-L and bushing Remover/Installer disc
onto screw. (2) Position assembly with receiver bridge support-
ing trailing arm while turning screw to begin bushing
removal. (3) After bushing has begun to move replace bushing
remover/installer (round disc) with bushing remover
(oval shaped disc). Use this assembly to finish pressing
bushing out of trailing arm (Fig. 8).
PIVOT BUSHING INSTALLATION
(1) Align the bushing with the bushing mounting
hole in the trailing arm bracket (Fig. 9). Tap bushing in
slightly to hold position. (2) Assemble bushing installer Tool onto press screw
and support bridge into press base. Position assem-
bly as shown in (Fig. 10) and press bushing into
arm to depth shown in (Fig. 9). (3) Position hanger bracket on pivot bushing, and
install through bolt, loose assemble nut (Fig. 11). Right
side trailing arm shown. (4) Position hanger to frame rail (a suitable drift will
aid in guiding hanger bracket into position). Install
and tighten screws to 75 N Im (55 ft. lbs.) torque (Fig.
12). Install lower shock absorber mounting bolt, but
do not tighten. (5) Position brake hose mounting bracket to trailing
arm, install and tighten retaining screw to 11 N Im (95
in. lbs.) torque (Fig. 13). (6) Attach park brake cable housing to hanger
bracket and cable to connector.
Fig. 8 Tools Installed To Remove Bushing
Fig. 6 Remove Pivot Bushing Hanger Bracket Bolts
Fig. 7 Remove Hanger Bracket
Ä SUSPENSION AND DRIVESHAFTS 2 - 53

PIVOT BUSHING AC AG AJ AP BODY
REMOVE FROM VEHICLE
(1) Raise vehicle (see Hoisting, Group 0). Remove
brake hose mounting bracket screw (Fig. 1). (2) Detach park brake cable at connector and from
hanger bracket (Fig. 1).
WARNING: WHEN REMOVING THE REAR AXLE
PIVOT BUSHING ON VEHICLES EQUIPPED WITH EI-
THER REAR COIL SPRINGS OR AIR SUSPENSION.
THE REAR AXLE MUST BE SUPPORTED BY THE
AXLE AND TRAILING ARM TO ENSURE ADEQUATE
SUPPORT OF REAR AXLE. (3) Support the rear axle assembly at both the axle
channel and the trailing arm with jack stands (Fig.
2). Then remove lower shock absorber to rear axle
mounting bolt (Fig. 2).
(4) Remove hanger bracket to frame rail bolts (Fig.
3). (5) Lower axle assembly down enough to remove
pivot bolt and hanger bracket (Fig. 3). Right side
trailing arm shown.
PIVOT BUSHING REMOVAL FROM AXLE AS- SEMBLY
Remove bushing with Remover/Installer Spe-
cial Tool C-4702-7 Press. And 3 piece set, Special
Tool C-4212 and C-4366-1 (Receiver Support
Bridge, Bushing Remover/Installer and Bushing
Remover). (1) Install receiver (support) cup C-4366-1 into base
of press C-4212 and Bushing Remover Cup C-4702-7
onto screw. (2) Position assembly with receiver bridge support-
ing trailing arm while turning screw to begin bushing
removal. (3) After bushing has begun to move replace bushing
remover/installer (round disc) with bushing remover
(oval shaped disc). Use this assembly to finish pressing
bushing out of trailing arm (Fig. 4).
PIVOT BUSHING INSTALLATION
(1) Align the bushing with the bushing mounting
hole in the trailing arm bracket (Fig. 5). Tap bushing in
slightly to hold it in position on trailing arm. (2) Assemble Bushing Installer Special Tool
C-4702-2 onto press screw and Support Cup Special
Fig. 1 Remove Brake Hose Mounting Bracket Screw and Park Brake Cable
Fig. 2 Remove Pivot Bushing Hanger Bracket Bolts
Fig. 3 Remove Hanger Bracket
Fig. 4 Tools Installed To Remove Bushing
Ä SUSPENSION AND DRIVESHAFTS 2 - 55

REAR AXLE ASSEMBLY
REMOVE
(1) Raise vehicle (see Hoisting, Group 0). Support
axle with jack stands and remove wheel and tire as-
sembly. (2) Separate park brake cable at connector. Detach
cable housing from hanger bracket (Fig. 1).
(3) Remove lock and separate brake tube assembly
from brake hose mounting bracket (Fig. 1). (4) Remove lower shock absorber through bolts and
track bar to axle pivot bolt. Support track bar end
with wire (Fig. 2).
(5) Lower axle until spring and isolator assemblies
can be removed. Remove spring and isolator assem-
blies (Fig. 3). (6) Support pivot bushing end of the trailing arms.
(as well as axle beam with jack stands) Remove pivot
bushing hanger bracket to frame screws. Lower and
remove axle assembly from vehicle. (7) Remove rear brake assemblies, see Group 5 for
proper procedure. (8) For pivot bushing removal and installation see
PIVOT BUSHING this group.
INSTALLATION
(1) Raise and support axle on jack stands.
(2) Attach pivot bushing hanger brackets to frame
rail (Fig. 4). Tighten screws to 61 N Im (45 ft. lbs.)
torque.
(3) Install springs and isolators (Fig. 5).
(4) Raise axle and install shock absorber and track
bar through bolts loose assemble only (Fig. 6).
(5) Install brake assembly as follows:
DRUM BRAKE ASSEMBLY
(1) Position spindle, seal, and brake support to
axle after routing park brake cable through trailing
arm opening and brake tube over arm (Figs. 1). In-
stall the 4 spindle mounting bolts finger tight. Then
torque the 4 spindle mounting bolts to 75 N Im (55 ft.
lbs.) torque. (2) Install brake drum and bearings.Fig. 1 Remove Brake Hose Mounting Bracket Screw and Park Brake Cable
Fig. 2 Remove Shock Absorber and Track Bar Bolts
Fig. 3 Remove/Install Coil Spring and Isolator Assembly
Fig. 4 Attach Hanger Brackets to Frame
Ä SUSPENSION AND DRIVESHAFTS 2 - 57

FRONT AND REAR AIR SPRINGS
The front and rear air springs are essentially pneu-
matic cylinders that replace the steel coil springs.
The air filled springs allow the vehicle suspension
height to be adjusted for all weight conditions. The air springs allow for the reduction of spring
rates to improve vehicle ride characteristics.
FRONT/REAR SPRING SOLENOIDS
The front and rear solenoids control air flow in and
out of the front and rear springs. The Air Suspension
Control Module (ASCM) opens the solenoids when
the system requires air to be added to or exhausted
from the air springs. The solenoids operate at a cur-
rent draw range of 0.6 to 1.5 amps.
HEIGHT SENSOR
A magnetic switch type sensor. Located in the
right rear shock absorber and left and right front
struts, (Fig. 2) monitors vehicle height. The sensors
transmit signals to the (ASCM) relating to vehicle
height status (low, trim, medium, high).
CONTROL MODULE
The Air Suspension Control Module (ASCM). Is a
device that controls the ground circuits for the Com-
pressor Relay, Compressor Exhaust Solenoid Valve
and Front and Rear Solenoid Valves. The (ASCM)
limits the compressor pump operation time to 170 to
190 seconds. This controlled operation time is to pre- vent damage to the compressor motor.
To prevent excessive cycling between the compres-
sor and the exhaust solenoid circuits during normal
ride conditions. A 14 to 16 second delay is incorpo-
rated in the microprocessor logic. The system is non-operation when one of the fol-
lowing conditions exists. A door(s) is/are open, the
trunk is open, the service brake is applied or the
throttle position sensor is 65% to 100% open. System
operation is inhibited during high speed cornering
activities or if there is a charging system failure.
The control module is on the CCD bus system.
COMPRESSOR ASSEMBLY
The compressor assembly is driven by an electric
motor and supplies air pressure between 930 to 1241
kPa (135 to 180 psi) (Fig. 3). A solenoid operated ex-
haust valve. Located in the compressor head assem-
bly, releases air when energized. A heat actuated circuit breaker. Located inside the
compressor motor housing. Is used to prevent damage
to the compressor motor in case of control module
failure.
COMPRESSOR AIR DRYER
The air dryer is attached to the compressor (Fig. 3).
This component serves two purposes. It absorbs mois-
ture from the atmosphere before it enters the system
Fig. 2 Front and Rear Air Springs
2 - 74 SUSPENSION AND DRIVESHAFTS Ä

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

expel all the trapped air. Be sure to monitor the fluid
level in the pressure bleeder. It must stay at the
proper level so air will not be allowed to reenter the
brake system through the master cylinder.
BLEEDING WITHOUT A PRESSURE BLEEDER
If a pressure bleeder is not available. A good brake
fluid flow can be obtained by manual bleeding of the
brake hydraulic system, following these steps. Manual bleeding of the brakes hydraulic sys-
tem will require the aid of a helper to correctly
perform manual brake bleeding procedure. 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
(1) Pump the brake pedal three or four times and
hold it down before the bleeder screw is opened. (2) Then open the bleeder screw at least 1 full
turn. When the bleeder screw opens the brake pedal
will drop all the way to the floor. (3) Release the brake pedal only afterthe bleeder
screw is closed. (4) Repeat steps 1 through 3, four or five times, at
each bleeder screw. This should pass a sufficient
amount of fluid to expel all the trapped air from the
brake system. Be sure to monitor the fluid level in
the master cylinder, so it stays at a proper level so
air will not reenter the brake system through the
master cylinder. Test drive vehicle to be sure brakes are operating
correctly and that pedal is solid.
TEST FOR FLUID CONTAMINATION
Indications of fluid contamination are swollen or
deteriorated rubber parts. Swollen rubber parts indicate the presence of petro-
leum in the brake fluid. To test for contamination, put small amount of
drained brake fluid in clear glass jar. If fluid sepa-
rates into layers, there is mineral oil contamination. If contaminated, drain and thoroughly flush sys-
tem. Replace master cylinder, proportioning valve,
caliper seals, wheel cylinder seals and all hoses.
WHEEL STUD NUT TIGHTENING
When tightening wheel stud nuts, a criss-cross
tightening sequence should be followed (Fig. 9).
Tighten all stud nuts to one-half specified torque.
Repeat, fully tightening to 129 N Im (95 ft. lbs.).
Fig. 9 Wheel Stud Nut Tightening Sequence
Fig. 7 Proper Method for Purging Air From Brake
System (Typical)
Fig. 8 Open Bleeder Screw at Least One Full Turn (Typical)
Ä BRAKES 5 - 7

BRAKE HOSE AND TUBING
INSPECTION OF BRAKE HOSE AND TUBING
Flexible rubber hose is used at both front brakes and
at the rear axle. Inspection of brake hoses should be
performed whenever the brake system is serviced and
every 7,500 miles or 12 months, whichever comes first
(every engine oil change). Inspect hydraulic brake
hoses for severe surface cracking, scuffing, or worn
spots. Should the fabric casing of the rubber hose be
exposed due to cracks or abrasions in the rubber hose
cover, the hose should be replaced immediately. Even-
tual deterioration of the hose can take place with
possible burst failure. Faulty installation can cause
twisting and wheel, tire or chassis interference. The steel brake tubing should be inspected periodi-
cally for evidence of physical damage or contact with
moving or hot components.
INSTALLATION OF BRAKE HOSE
Always use factory recommended brake hose to en-
sure quality, correct length and superior fatigue life.
Care should be taken to make sure that the tube and
hose mating surfaces are clean and free from nicks and
burrs. Front right and left side hoses are not
interchangeable. Connections should be correct and properly made.
Use new copper seal washers on all connections using
Banjo Bolts and tighten all fittings to their specified
torques. The flexible front hydraulic brake hose should al-
ways be installed on the vehicle by first attaching the
Banjo connector to the caliper assembly. Then bolt the
intermediate hose bracket to the strut assembly allow-
ing the bracket to position the hose to prevent twisting.
Attach the hose to the body bracket and steel brake
tubing. Tighten all fittings to specified torque. The
body bracket and hose end are keyed so that they will
only fit one way. Install rear brake hoses first to the trailing arm
tubes and then to the floor pan tubes. Minimize hose
twisting. Vehicles equipped with rear disc brakes have
brake hoses attached to the caliper on each side. The
brake hose should be first attached by the Banjo bolt to
the caliper and then secured to the hose bracket with
the retaining clip. The attach the steel brake tubing to
the hose fitting.
REPAIR AND INSTALLATION OF BRAKE TUB- ING
Only double wall 4.75mm (3/16 in.) steel tubing
should be used for replacement. Care should be taken
when replacing brake tubing, to be sure the proper
bending and flaring tools and procedures are used, to
avoid kinking. Do not route the tubes against sharp edges, moving components or into hot areas. All
tubes should be properly attached with recommended
retaining clips.
TYPES OF TUBING FLARES
Two different tubing flares (Fig. 13) are used on 93
M.Y. vehicles. On some ABS brake systems the tub-
ing connections made to the hydraulic assembly use
an ISO flare. All other ABS brake system compo-
nent, tubing connections are made using a double in-
verted flare. On non-ABS brake systems all
component tubing connections use only the double in-
verted flare. No ISO flares are used.
CAUTION: ALWAYS USE THE PROPER FLARING
TOOL AND PROCEDURE, FOR THE TYPE OF
BRAKE SYSTEM THAT IS BEING SERVICED TO IN-
SURE THE INTEGRITY OF THE HYDRAULIC SYS-
TEM.
TO REPAIR OR FLARE TUBING
Using Tubing Cutter, Special Tool C-3478-A or
equivalent, cut off damaged seat or tubing (Fig. 14).
Ream out any burrs or rough edges showing on in-
side of tubing (Fig. 15). This will make the ends of
tubing square (Fig. 15) and ensure better seating of
flared end tubing. PLACE TUBE NUT ON TUB-
ING BEFORE FLARING THE TUBING.
DOUBLE INVERTED TUBING FLARES.
To make a double inverted tubing flare (Fig. 13 &
16). Open handles of Flaring Tool, Special Tool
C-4047 or equivalent. Then rotate jaws of tool until
the mating jaws of tubing size are centered between
vertical posts on tool. Slowly close handles with tub-
Fig. 13 Identifying Hydraulic Brake Tubing Flares
Ä BRAKES 5 - 11