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2 - 58 SUSPENSION/DRIVESHAFTS

(6)Attach park brake cable housing to hanger bracket and cable to connector.

(7)Lower vehicle with suspension supporting vehicle weight, trailing arm at design height. Tighten

pivot bolt nut and lower shock absorber mounting bolt to 61 NIm (45 ft. lbs.) torque.

REAR AXLE ASSEMBLY

REMOVE

(1)Raise vehicle (see Hoisting, Group 0). Support axle with jack stands and remove wheel and tire assembly.

(2)Separate park brake cable at connector. Detach cable housing from hanger bracket (Fig. 1).

Fig. 1 Remove Brake Hose Mounting Bracket Screw

and Park Brake Cable

(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).

Fig. 2 Remove Shock Absorber and Track Bar Bolts

(5) Lower axle until spring and isolator assemblies can be removed. Remove spring and isolator assemblies (Fig. 3).

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Fig. 3 Remove/Install Coil Spring and Isolator As-

sembly

(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 NIm (45 ft. lbs.) torque.

Fig. 4 Attach Hanger Brackets to Frame

(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:

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Fig. 5 Install Springs and Isolators

Fig. 6 Install Shock Absorber and Track Bar Fasteners (Bolts)

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). Install the

4 spindle mounting bolts finger tight. Then torque the 4 spindle mounting bolts to 75 NIm (55 ft. lbs.) torque.

(2)Install brake drum and bearings.

(3)Install washer and nut. Tighten nut to 27-34 NIm (240-300 in. lbs.) torque while rotating brake drum. Then back off nut to completely release preload. Finger tighten nut.

SUSPENSION/DRIVESHAFTS 2 - 59

(4)Position nut lock with one pair of slots in-line with cotter pin hole. Install cotter pin. Clean and install grease cap.

DISC BRAKE ASSEMBLY

(1)Position caliper support and spindle to axle.

Install the 4 spindle mounting bolts finger tight. Then torque the 4 spindle mounting bolts to 75 NIm (55 ft. lbs.) torque.

(2)Install hub and bearings.

(3)Install washer and nut. Tighten to 27-34 NIm (240-300 in. lbs.) torque while rotating hub. Then back off nut to completely release preload. Finger tighten nut.

(4)Position nut lock with one pair of slots in-line with cotter pin hole. Install cotter pin. Clean and install grease cap.

(5)Install braking disc and adapter. Install caliper assembly (see Rear Disc Brake) in Brakes Section, Group 5.

(6)Attach brake hose and parking brake cable to caliper and suspension arm (Fig. 7). Install brake hose mounting bracket to caliper support.

(7)Route park brake cable through hanger bracket and lock housing end into bracket. Install cable end into (intermediate) connector (Fig. 7).

(8)Install brake hose and fitting into bracket and

install lock. Attach brake tube assembly to hose fitting and tighten to 16 NIm (140 in. lbs.) torque (Fig. 7).

(9)Install wheel and tire assemblies and tighten wheel stud nuts to 129 NIm (95 ft. lbs.) torque. Remove jacks and lower vehicle.

(10)With suspension supporting vehicle tighten lower shock absorber bolts to 61 NIm (45 ft. lbs.) torque and track bar bolt to 95 NIm (70 ft. lbs.) torque.

(11)Bleed brake system. See BRAKES, Group 5.

GENERAL INFORMATION

The automatic air load leveling system includes the following (Fig. 1).:

²Compressor Assembly

²Control Module Wiring Harness

²Air Lines

²Compressor Relay

²Air Shock Absorbers

²Air Dryer

This system is used to supplement standard suspension systems on vehicles so equipped.

MAJOR COMPONENTS

COMPRESSOR ASSEMBLY

The compressor assembly is driven by an electric motor and supplies air pressure between 1172 to 1516 kPa (170 to 220 psi) (Fig. 2). A solenoid operated exhaust valve, located in the compressor head assembly, releases air when energized.

CONTROL MODULE

The Control Module (CM) is a device that controls the ground circuits for the compressor relay and the exhaust valve solenoid. A microprocessor within the module limits the compressor pump operation time to 140 to 160 seconds. To prevent damage to the compressor motor.

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Fig. 2 Compressor Assembly

In addition, there is an air regeneration cycle that is controlled by the Control Module (CM). If the height sensor signal is in the neutral or high position. When the ignition switch is turned to the ON position, after a 22 to 28 second delay, the compressor will run from 2 to 6 seconds.

To prevent excessive cycling between the compressor and the exhaust solenoid circuits during normal ride conditions. A 12 to 18 second delay is incorporated in the microprocessor.

HEIGHT SENSOR

A magnetic switch type sensor, located in the right air shock absorber, monitors rear vehicle height. The sensor sends signals to the (CM) relating to vehicle rear suspension status (low, trim, high).

AIR LINES AND FITTINGS

To release an air supply line from a rear shock absorber assembly. Push in (toward schock absorber) on the plastic ring of the shock absorber air line fitting. Then while holding in the plastic ring on shock absorber fittig pull the air supply line strait out of fitting (Fig. 3).

The fitting has a unique push-in feature. A brass type collet locks the air line in place. One rubber O-ring seals the air line to prevent air leakage. To attach air line, push into fitting (Fig. 4).

COMPRESSOR RELAY

The relay is mounted to a bracket on the Control Module (CM). When the relay is energized, it allows the compressor to operate. This unit is controlled by the CM.

AIR ADJUSTABLE SHOCK ABSORBERS

Air shock absorbers are essentially hydraulic shock absorbers with a neoprene bladder sealing the upper and lower sections together, forming an air cylinder.

SUSPENSION/DRIVESHAFTS 2 - 61

Fig. 3 Release Air Line from Fitting

Fig. 4 Push Air Line into Fitting

AIR DRYER

The air dryer is attached to the compressor. This component serves two purposes; it absorbs moisture from the atmosphere before it enters the system. And with the internal valves maintains a residual system pressure of 69 to 152 kPa (10 to 22 psi).

AIR CHECK, RESIDUAL (FIG. 5).

The air dryer has a valves arrangement that maintains 69 to 152 kPa (10 to 22 psi) in the air shocks. This is to improve the ride characteristics of the vehicle under light load conditions. To test this function, perform the following procedure:

(1)Remove the air line from the dryer and right shock absorber. Attach a piece of bulk nylon tubing to one side of a Pressure Gauge (0-300 psi), and to the right shock absorber (Fig. 5).

(2)Attach another piece of nylon tubing from the dryer (compressor) to other side of the pressure gauge.