Hummer H2. Manual - part 2229

compressor. The valves are activated and controlled independently by the air suspension module.

Rear Air Springs

The air springs are mounted in the frame in the same location were the coil spring is mounted for a vehicle
without air suspension. Support pieces are affixed to the axle for the air springs.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Special Tools

Illustration

Tool Number/Description

CH 47816

Suspension Position Calibration Blocks

2004 Hummer H2

2004 SUSPENSION Air Suspension - Hummer H2

2003-04 WHEEL ALIGNMENT

Specifications & Procedures - Hummer - H2

MEASURING WHEEL ALIGNMENT

Steering and vibration complaints are not always the result of improper alignment. One possible cause is wheel
and tire imbalance. Another possibility is tire lead due to worn or improperly manufactured tires. Lead/pull is
defined as follows: At a constant highway speed on a typical straight road, lead/pull is the amount of effort
required at the steering wheel to maintain the vehicle's straight path. Lead is the vehicle deviation from a
straight path on a level road without pressure on the steering wheel. Before performing any adjustment affecting
wheel alignment, perform the following inspections and adjustments in order to ensure correct alignment
readings:

Inspect the tires for the proper inflation and irregular tire wear.

Inspect the runout of the wheels and the tires.

Inspect the wheel bearings for backlash and excessive play.

Inspect the ball joints and tie rod ends for looseness or wear.

Inspect the control arms and stabilizer shaft for looseness or wear.

Inspect the steering gear for looseness at the frame.

Inspect the struts/shock absorbers for wear, leaks, and any noticeable noises.

Inspect the vehicle trim height.

Inspect the steering wheel for excessive drag or poor return due to stiff or rusted linkage or suspension
components.

Inspect vehicle load: Inspect the fuel level. The fuel tank should be full or the vehicle should have a
compensating load added. Give consideration to excess loads, such as tool boxes, sample cases, etc. If
normally carried in the vehicle, these items should remain in the vehicle during alignment adjustments.
Give consideration also to the condition of the equipment being used for the alignment. Follow the
equipment manufacturer's instructions. Satisfactory vehicle operation may occur over a wide range of
alignment settings. However, if the setting exceeds the service allowable specifications, correct the
alignment to the service preferred specifications.

Install the alignment equipment according to the manufacturer's instructions. Jounce the front and the rear
bumpers 3 times prior to checking the wheel alignment. Measure the alignment angles and record the
readings.

TRIM HEIGHT

TRIM HEIGHT MEASUREMENTS

Trim height is a predetermined measurement relating to vehicle ride height. Incorrect trim heights can cause
bottoming out over bumps, damage to the suspension components and symptoms similar to wheel alignment
problems. Check the trim heights when diagnosing suspension concerns and before checking the wheel
alignment. Perform the following before measuring the trim heights:

2004 Hummer H2

2003-04 WHEEL ALIGNMENT Specifications & Procedures - Hummer - H2

2004 Hummer H2

2003-04 WHEEL ALIGNMENT Specifications & Procedures - Hummer - H2

1. Set the tire pressures to the pressure shown on the certification label.

2. Check the fuel level. Add additional weight if necessary to simulate a full tank.

3. Make sure the rear compartment is empty except for the spare tire.

4. Make sure the vehicle is on a level surface, such as an alignment rack.

Z Height Measurement

1. By hand, lift the front bumper of the vehicle up about 1.5 in. (38 mm).

2. Release vehicle.

3. Allow the vehicle to settle into position.

4. Repeat this jouncing operation 2 more times for a total of 3 times.

5. Measure from the pivot bolt center line (3) down to the lower corner (5) of the lower ball joint (1) in

order to obtain the Z height measurement (4). See Fig. 1 .

6. Push the front bumper of the vehicle down about 1.5 in. (38 mm).

7. Release vehicle.

8. Allow the vehicle to rise.

9. Repeat the operation for a total of 3 times.

10. Measure the Z dimension.

11. The true Z height dimension number is the average of the high and the low measurements. See TRIM

HEIGHT SPECIFICATIONS .

Fig. 1: Measuring Z Height
Courtesy of GENERAL MOTORS CORP.

Z Height Adjustment

2004 Hummer H2

2003-04 WHEEL ALIGNMENT Specifications & Procedures - Hummer - H2

1. For vehicles equipped with a torsion bar suspension turn the bolt (1) that contacts the torsion arm

clockwise to raise the and counterclockwise to lower the height adjustment. See Fig. 2 . One revolution of
the bolt (1) into the nut increases the Z height by approximately 0.2 in. (6.0 mm).

2. For vehicles without torsion bars, replace damaged or worn components as necessary.

Fig. 2: Adjusting Z Height
Courtesy of GENERAL MOTORS CORP.

D Height Measurement

1. With the vehicle on a flat surface, lift upward on the rear bumper 1.5 in. (38 mm).

2. Release vehicle.

3. Allow the vehicle to settle into position.

4. Repeat the jouncing operation 2 more times for a total of 3 times.

5. The D height is obtained by measuring the distance between the edge of the jounce cup along the jounce

bumper center line and the jounce pad on the rear axle. See Fig. 3 .

6. If these measurements are out of specifications, inspect for the following conditions:

Sagging front suspension. May need to replace torsion bar.

Sagging rear coil springs. May need to replace rear suspension Coil Springs.

Proper air suspension operation.

Worn rear suspension components.

Improper tire inflation.

Improper weight distribution.

Collision damage.

NOTE:

The D height dimension measurement determines the proper rear end ride
height. There is no adjustment procedure. Repair may require replacement of
suspension components.

2004 Hummer H2

2003-04 WHEEL ALIGNMENT Specifications & Procedures - Hummer - H2

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