Suspension System General Diagnosis Cadillac Escalade GMT800

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Diagnostic Starting Point - Suspension General Diagnosis

Begin the system diagnosis by reviewing the system Description and Operation. Reviewing the Description and Operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information, and the vehicle RPO, will also help you determine if the condition described by the customer is normal operation. Refer to SYMPTOMS - SUSPENSION GENERAL DIAGNOSIS in order to identify the correct procedure for diagnosing the system and where the procedure is located.

Symptoms - Suspension General Diagnosis

Important: The following steps must be completed before using the symptom tables.

1. Review the system description and operation in order to familiarize yourself with the system functions.
2. Refer to the appropriate description and operation: GENERAL DESCRIPTION (TORSION BAR) in Front Suspension GENERAL DESCRIPTION in Rear Suspension GENERAL DESCRIPTION in Tires and Wheels

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of any of the Suspension subsystems.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Inspect for proper tire size and inflation pressure. Refer to

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. Ride Diagnosis, See «Ride Diagnosis»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
2. Vehicle Leads/Pulls, See «Vehicle Leads/Pulls»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
3. Body Leans or Sways in Corners, See «Body Leans Or Sways In Corners»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
4. Suspension Bottoms, See «Suspension Bottoms»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
5. Memory Steer, See «Memory Steer»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
6. Poor Directional Stability, See «Poor Directional Stability»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
7. «BALL JOINT INSPECTION»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
8. Noise Diagnosis - Front Suspension, See «NOISE - Front Suspension»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
9. Noise Diagnosis - Rear Suspension, See «NOISE - Rear Suspension»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
10. Struts or Shock Absorbers On-Vehicle Testing, See «Struts Or Shock Absorbers On-Vehicle Testing»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
11. Wheel Bearings Diagnosis, See «Wheel Bearing»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
12. RADIAL TIRE LEAD/PULL CORRECTION

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Important

1. The vehicle must rest on a level surface.
2. The vehicle must be stable. Do not rock the vehicle on the floor stands.
3. The upper control arm bumper must not contact the frame.

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1. Raise and support the vehicle. Refer to «LIFTING AND JACKING THE VEHICLE»(/cadillac/escalade/gmt800-2001-2006/remont/hoistjack/#jacking-and-lifting-avalanche__lifting-and-jacking-the-vehicle) in General Information.
2. Support the lower control arm with a floor stand or jack, as far outboard as possible. Important: If a seal is cut or torn, replace the ball joint.
3. Clean and inspect the ball joint seals for cuts or tears. If the ball joint seals are damaged, replace the ball joint. Refer to LOWER BALL JOINT REPLACEMENT (COIL SPRING SUSPENSION) or LOWER BALL JOINT REPLACEMENT (TORSION BAR SUSPENSION) or UPPER CONTROL ARM REPLACEMENT in Front Suspension.
4. Check the wheel bearing for looseness. If looseness in the wheel bearing is present, refer to Wheel Bearings Diagnosis, See «Wheel Bearing»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
5. Check the ball joints for horizontal looseness. Position the J 8001 dial indicator against the lowest outboard point on the wheel rim. Rock the wheel in and out while reading the dial indicator. This shows horizontal looseness in both joints. The dial indicator reading should be no more than 2 mm (0.080 in). If the reading is too high, check the lower ball joints for vertical looseness. NOTE: Do not pry between the lower arm and the wheel drive shaft boot or in such a manner that the ball joint seal is contacted. Damage to the wheel drive shaft boot will result (4WD).
6. For 4WD vehicles, place a J 8001 dial indicator (1) against the spindle in order to show vertical movement.
7. Pry between the lower control arm (2) and the outer bearing race (1) while reading the dial indicator. This shows vertical looseness in the lower ball joints. The lower ball joint may show some looseness.
8. If the dial indicator reading is more than 3.18 mm (0.125 in), replace the lower ball joint. Refer to LOWER BALL JOINT REPLACEMENT (COIL SPRING SUSPENSION) or LOWER BALL JOINT REPLACEMENT (TORSION BAR SUSPENSION) in Front Suspension.
9. If the lower ball joint is within specifications, and there is too much horizontal looseness, check the upper ball joint for wear, Disconnect the upper ball joint from the steering knuckle. Refer to UPPER CONTROL ARM REPLACEMENT in Front Suspension. If you find any looseness or can twist the upper ball joint stud with your fingers, replace the upper control arm. Refer to UPPER CONTROL ARM REPLACEMENT in Front Suspension.

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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

1. Make sure the vehicle is on a level surface, such as an alignment rack.
2. Remove the alignment rack floating pins.
3. Set the tire pressures to the pressure shown on the certification label.
4. Check the fuel level. Add additional weight if necessary to simulate a full tank.
5. To ensure proper weight distribution make sure the rear storage compartment is empty.
6. Close the doors and hood.

Z Height Measurement

Important: K models only the Z height must be adjusted before the alignment.

The Z height dimension measurement determines the proper ride height for the front end of the vehicle. Vehicles equipped with torsion bars use a adjusting arm in order to adjust the Z height dimension. Vehicles without torsion bars have no adjustment and could require replacement of suspension components.

Important: All dimensions are measured vertical to ground. Cross vehicle Z heights should be within 12 mm (0.47 in) to be considered correct.

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1. Place hand on the front bumper and jounce the front of the vehicle. Make sure that there is at least 38 mm (1.5 in) of movement while jouncing.
2. Allow the vehicle to settle into position.
3. Measure from the pivot bolt center line (2) down to the lower corner (5) of the lower steering knuckle (1) in order to obtain the Z height measurement (4).
4. Repeat the jouncing operation 2 more times for a total of 3 times.
5. Use the highest and lowest measurements to calculate the average height.
6. The true Z height dimension number is the average of the highest and the lowest measurements. Refer to «TRIM HEIGHT SPECIFICATIONS»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis) .

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1. For vehicles equipped with a torsion bar suspension turn the bolt (1) that contacts the torsion arm as needed. One revolution of the bolt (1) into the nut increases the Z height by approximately 6.0 mm (0.2 in).
2. For vehicles without torsion bars, replace damaged or worn components as necessary.
3. If these measurements are still out of specifications after adjustment or are not equipped with torsion bars, inspect for the following: Sagging front suspension. Refer to TORSION BAR REPLACEMENT in Front Suspension. Collision Damage

D Height Measurement

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

Important: All dimensions are measured vertical to ground. Cross vehicle D heights should be within 10 mm (0.39 in) to be considered correct.

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1. Place hand on the rear bumper and jounce the rear of the vehicle. Make sure that there is at least 38 mm (1.5 in) of movement while jouncing.
2. With the vehicle on a flat surface, lift upward on the rear bumper 38 mm (1.5 in).
3. Allow the vehicle to settle into position. Important: Measure the metal to metal contact points of the rear axle to the frame on the inboard side of the leaf springs.
4. Measure the D height by measuring the distance between the bumper bracket and the top of the rear axle tube.
5. Repeat the jouncing operation 2 more times for a total of 3 times.
6. Use the highest and lowest measurements to calculate the average height.
7. The true D height dimension number is the average of the highest and the lowest measurements. Refer to «TRIM HEIGHT SPECIFICATIONS»(/cadillac/escalade/gmt800-2001-2006/remont/suspension-front/#suspension-system-general-diagnosis)
8. If these measurements are out of specifications, inspect for the following conditions: Sagging front suspension Refer to TORSION BAR REPLACEMENT in Front Suspension. Sagging rear leaf/coil springs Refer to LEAF SPRING REPLACEMENT or COIL SPRING REPLACEMENT in Rear Suspension. Worn rear suspension components, such as leaf spring bushings Refer to SPRING BUSHING REPLACEMENT in Rear Suspension. Improper tire inflation. Improper weight distribution Collision damage

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See also:
• LIFTING AND JACKING THE VEHICLE
• SYMPTOMS - SUSPENSION GENERAL DIAGNOSIS
• Ride Diagnosis