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‌SPECIFICATIONS

SUSPENSION

Suspension General Diagnosis - Volt

TRIM HEIGHT SPECIFICATIONS



Model

Tire Size

P

± 12 mm (0.5

in)

R

± 12 mm (0.5

in)

Z

± 10 mm

(0.4 in)

D

± 10 mm (0.4

in)

Front

All

P215/50R17

687 mm

(27.05 in)

700 mm

(27.56 in)

21 mm

(0.83 in)

255 mm

(10.04 in)

DIAGNOSTIC INFORMATION AND PROCEDURES

SYMPTOMS - SUSPENSION GENERAL DIAGNOSIS


IMPORTANT: The following step must be completed before using the symptom tables.


Review the system description and operation in order to familiarize yourself with the system functions. Refer to the appropriate description and operation:

image Front Suspension Description and Operation for the front suspension

image Rear Suspension Description and Operation for the rear suspension

image General Description for tires and wheels


Visual/Physical Inspection


image Inspect for aftermarket devices which could affect the operation of any of the suspension subsystems.

image Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

image Inspect for proper tire size and inflation pressure. Refer to Vehicle Certification, Tire Placard, Anti- Theft, and Service Parts ID Label .

Symptom List


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

image Ride Diagnosis

image Vehicle Leads/Pulls image Suspension Bottoms image Torque Steer

image Memory Steer

RIDE DIAGNOSIS

Step

Action

Yes

No


1

Did you review the General Description and perform the necessary inspections?


Go to Step 2

Go to Symptoms - Suspension General Diagnosis


2

NOTE:

Verify the vehicle suspension package RPO.

Verify that the ride is too soft or too hard.Does the vehicle ride normally?


System OK


Go to Step 3


3

Check the tire inflation and adjust to specifications. Refer to Vehicle Certification, Tire Placard, Anti- Theft, and Service Parts ID Label .

Did you adjust the tire pressure?


Go to Step 6


Go to Step 4


4

Inspect the vehicle trim height. Refer to Trim Height Inspection.

Did you find and correct the condition?


Go to Step 6


Go to Step 5


5

Inspect the following suspension components for wear or damage:

image Shock Absorbers - Refer to Strut and Shock Absorber Inspection , for front and Strut and Shock Absorber Inspection for rear.

image Springs


Did you find and correct the condition?


Go to Step 6


-

6

Drive the vehicle in order to verify the repair. Did you correct the condition?


System OK


Go to Step 3

VEHICLE LEADS/PULLS


Step

Action

Yes

No

DEFINITION: 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.


1

Did you review the General Description and perform the visual/physical inspections?


Go to Step 2

Go to Symptoms - Suspension General Diagnosis

2

Road test the vehicle in order to verify the complaint. Does the vehicle operate normally?


System OK


Go to Step 3


3

Inspect the tire/wheel assemblies for the following conditions:


Go to Step 9


Go to Step 4

Step

Action

Yes

No


image Correct tire pressure - Refer to the tire placard. image Correct tire size - Refer to the tire placard.

image Abnormal tire wear or damage


Did you find and correct the condition?



4

Perform the Radial Tire Lead/Pull Correction . Did you find and correct the condition?


Go to Step 9


Go to Step 5


5

Inspect and correct/adjust the suspension and steering systems for the following conditions:

image Vehicle trim height - Refer to Trim Height Specifications .

image Excessively worn, loose, or damaged components


Did you find and correct the condition?


Go to Step 9


Go to Step 6


6

Inspect the brake system for brake drag. With the vehicle suspended on a hoist, brake drag can be identified by rotating each wheel several times and observing whether more force is need to rotate the left wheel or the right wheel. Refer to Brake Rotor Thickness Variation Measurement .

Did you find and correct the condition?


Go to Step 9


Go to Step 7


7

Inspect the wheel alignment and adjust as necessary. Refer to Wheel Alignment Measurement .

Did you correct the condition?


Go to Step 9


Go to Step 8


8

Inspect the steering gear for unequal effort. The vehicle must be suspended on a hoist, the engine running, and the transmission in PARK or NEUTRAL. Grasp the tire assembly and manually simulate a turn from the left of center and the right of center observing whether more force is needed to turn to the left or to the right. If this condition exists replace the steering gear.

Did you correct the condition?


System OK


Go to Step 3

9

Operate the vehicle in order to verify the repair. Did you correct the condition?


System OK


Go to Step 3

BODY LEANS OR SWAYS IN CORNERS


Step

Action

Yes

No

1

Did you review the General Description and perform the necessary inspections?


Go to Step 2

Go to Symptoms - Suspension General

Step

Action

Yes

No




Diagnosis

2

Verify the vehicle leans or sways in corners. Does the vehicle operate normally?


System OK


Go to Step 3


3

Inspect the following components for wear or damage:

image Rear Coil Springs image Front Coil Springs


Are the components worn or damaged?


Go to Step 5


Go to Step 4


4

1. Inspect the stabilizer shaft link for wear or damage.

2. Repair as necessary.

Did you find and correct the condition?


Go to Step 6


Go to Step 2

5

Replace the springs as necessary. Did you complete the repair?


Go to Step 6


-

6

Operate the vehicle in order to verify the repair. Did you correct the condition?


System OK


Go to Step 3

SUSPENSION BOTTOMS


Step

Action

Yes

No

DEFINITION: A loud bang or thump that can usually be felt and/or heard when the vehicle is driven over bumps. This condition is commonly noticed when the vehicle trim height is too low.


1

Did you review the General Description and perform the necessary inspections?


Go to Step 2

Go to Symptoms - Suspension General Diagnosis

2

Verify that the suspension bottoms. Does the vehicle operate normally?


System OK


Go to Step 3


3

Inspect for vehicle overloading and correct the overloading condition as necessary. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label for specifications.

Did you find and correct the condition?


Go to Step 6


Go to Step 4


4

Inspect the following components:

image Inspect the shock absorbers. Refer to Strut and Shock Absorber Inspection , for front and Strut and Shock Absorber Inspection for rear.

image Inspect for damaged coil springs, torsion bar or leaf springs and replace as necessary.


Go to Step 6


Go to Step 5

Step

Action

Yes

No



Did you find and correct the condition?




5

Inspect the vehicle trim height. Refer to Trim Height Inspection.

Did you complete the trim height inspection

procedure?


Go to Step 6


-

6

Operate the vehicle in order to verify the repair. Did you correct the condition?


System OK


Go to Step 3

TORQUE STEER


Step

Action

Yes

No

DEFINITION: On a dry, smooth, flat road, the vehicle has a left or right steering force only during

acceleration.


1

Did you review the General Description and perform the necessary inspections?


Go to Step 2

Go to Symptoms - Suspension General Diagnosis


2

1. Drive the vehicle on a straight, smooth, flat road.

2. Press the accelerator and determine if any additional steering input is required to maintain a straight ahead direction.

3. Repeat this test with the vehicle traveling in the opposite direction in order to eliminate crosswind effects. Lead/pull caused by unlevel roads and crosswinds are considered normal.

Does the vehicle exhibit torque steer when the accelerator is pressed?


Go to Step 3


System OK


3

1. Drive the vehicle on a straight, smooth, flat road at 64 - 97 km/h (40 - 60 mph).

2. Remove your foot from the accelerator.

3. Shift the transmission into NEUTRAL in order to allow the vehicle to coast.

4. Is any additional steering input required to maintain a straight ahead direction.

5. Repeat this test with the vehicle traveling in the opposite direction in order to eliminate crosswind effects. Lead/pull caused by unlevel roads and crosswinds are considered normal.

Does the vehicle direction change when the steering


Go to Vehicle Leads/Pulls


Go to Step 4

Step

Action

Yes

No


wheel is momentarily released?




4

Inspect the front suspension and powertrain mounts for worn or damaged components and repair as necessary.

Did you find and correct the condition?


Go to Step 6


Go to Step 5


5

Inspect the vehicle trim height. Refer to Trim Height Inspection.

Did you find and correct the condition?


Go to Step 6


-

6

Operate the vehicle in order to verify the repair. Did you correct the condition?


System OK

-

MEMORY STEER


Step

Action

Yes

No

DEFINITION: A lead or pull in the direction the driver previously turned the vehicle. Additionally, after turning in the opposite direction, the vehicle will want to lead or pull in that direction.


1

Did you review the General Description and perform the necessary inspections?


Go to Step 2

Go to Symptoms - Suspension General Diagnosis

2

Verify that memory steer is present. Does the system operate normally?


System OK


Go to Step 3


3

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .

2. Lubricate the tie rod ends and the ball joints if applicable.

3. Inspect the suspension system for worn or damaged components.

4. Repair as necessary.

Did you find and correct the condition?


Go to Step 7


Go to Step 4


4

Inspect for binding strut bearings.

1. Disconnect the strut from the steering knuckle.

2. If the strut is abnormally difficult to rotate, repair or replace the upper bearing mount.


Did you find and complete the repair?


Go to Step 7


Go to Step 5


5

Inspect for binding in the lower ball joints. If joint is binding, replace the joint.

Did you find and complete the repair?


Go to Step 7


Go to Step 6


6

Inspect the wheel alignment and adjust as necessary. Refer to Wheel Alignment Measurement .

Did you complete the wheel alignment?


Go to Step 7


-

Step

Action

Yes

No

7

Operate the vehicle in order to verify the repair. Did you correct the condition?


System OK

-

WHEEL BEARINGS DIAGNOSIS


Step

Action

Values

Yes

No


1

Did you review the General Description and perform the necessary inspections?


-


Go to Step 2

Go to Symptoms

- Suspension General Diagnosis


2

Road test the vehicle in order to verify the customer's complaint.

Does the vehicle operate normally?


-


System OK


Go to Step 3


3

1. Raise and support the vehicle. Refer to

Lifting and Jacking the Vehicle .

2. Inspect for tire or wheel damage. Refer to Tire and Wheel Assembly Runout Measurement - On-Vehicle .

Did you find and correct the condition?


-


Go to Step 7


Go to Step 4


4

1. Install the J 39570 chassis ear.

2. Road test the vehicle to verify the location of the wheel bearing noise.

Did you locate the source of the wheel bearing noise?


-


Go to Step 6


Go to Step 5


5


IMPORTANT:

Support the vehicle by the lower control arms or the rear axle to prevent movement during wheel bearing/hub inspection.


1. Mount and secure the J 8001 dial indicator set.

2. Ensure that the dial indicator contacts the vertical surface of the wheel as close as possible to the top wheel stud.

3. Push and pull on the top of the tire in order to inspect the total travel indicated by the dial indicator.

Is the measurement greater then the specified value?


0.127 mm

(0.005 in)


Go to Step 6


System OK

Step

Action

Values

Yes

No


6

Replace the wheel bearing. Refer to Front Wheel Bearing and Hub Replacement , or Rear Wheel Bearing and Hub Replacement . Did you complete the repair?


-


Go to Step 7


-

7

Road test the vehicle to verify the repair. Does the vehicle operate normally?

-


System OK


Go to Step 3

TRIM HEIGHT INSPECTION

Trim Height Measurement


Trim height is a predetermined measurement relating to vehicle ride height. Incorrect trim heights can cause the vehicle to bottom 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:

image Set the tire pressure to the specifications shown on the certification label. Refer to Vehicle Certification, Tire Placard, Anti-Theft, and Service Parts ID Label


NOTE: One U.S. gallon of gasoline weights approximately 6.5 lbs. One liter of gasoline weights approximately 0.7 kg.


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

image Make sure the passenger and rear compartments are empty, except for the spare tire. image Make sure the vehicle is on a flat and level surface, such as an alignment rack.

image Check that all the vehicle doors are securely closed.

image Check that the vehicle hood and rear deck lids are securely closed.

image Check for installed after market accessories or modifications that could affect trim height measurement: image Larger or Smaller than production wheels and tires.

image Lifting or Lowering Kits

image Wheel Opening Flares or Ground Affects


Measuring the P and R Dimension


image


Fig. 1: Identifying P And R Dimension Courtesy of GENERAL MOTORS COMPANY

Measurement Definitions

P Height: The vertical distance from the ground to the top of the wheel opening through the centerline of the front wheel.

R Height: The vertical distance from the ground to the top of the wheel opening through the centerline of the rear wheel.

Use the following procedures to measure the P and R dimensions:


NOTE: image Measure from the center of the wheel well opening to the ground.

image The left and right P and R height differences should be no more than 10 mm (0.39 in).


1. Push the front bumper down a minimum of 25 mm (1 in) and release. Perform this step three times.

2. Measure and record the trim height per the "Measurement Definitions" above.

3. Lift the bumper up a minimum of 25 mm (1 in) and release. Perform this step three times.

4. Measure and record the trim height per the "Measurement Definitions" above.

5. The true P height measurement is the average of the measurements taken in step 2 and 4. Refer to Trim Height Specifications

6. Repeat the above steps at the rear of the vehicle for the R heights.

7. If the P and R heights are outside of the specifications, measure the Z & D heights.


Measuring the Z Dimension


image


Fig. 2: Identifying Z Height Dimension Courtesy of GENERAL MOTORS COMPANY

Measurement Definitions

The Z Height: The vertical distance from the front lower control arm rear bushing rear attach bolt head surface

(2) to the center of the ball joint cup (1).

image


Fig. 3: Center Of Ball Joint Cup

Courtesy of GENERAL MOTORS COMPANY

Call out (1) is the center of the ball joint cup.


image


Fig. 4: Front Lower Control Arm Rear Bushing Rear Attach Bolt Head Surface Courtesy of GENERAL MOTORS COMPANY

Call out (2) is the front lower control arm rear bushing rear attach bolt head surface. Use the following procedures to measure the Z dimensions:

NOTE: The left and right Z height differences should be no more than 10 mm (0.39 in).


1. Push the front bumper down a minimum of 25 mm (1 in) and release. Perform this step three times.

2. Measure and record the trim height per the "Measurement Definitions" above.

3. Lift the front bumper a minimum of 25 mm (1 in) and release. Perform this step three times.

4. Measure and record the trim height per the "Measurement Definitions" above.

5. The true Z height dimension is the average of the measurements taken in steps 2 and 4. Refer to Trim Height Specifications

6. If these measurements are out of specifications, inspect for the following conditions: image Worn or damaged suspension components

image Collision damage


D Height Measurement


image


Fig. 5: Identifying D Height

Courtesy of GENERAL MOTORS COMPANY Measurement Definitions

The D Height: The vertical distance from the bottom surface of the body side rail (1) to the center of the lower shock attaching bolt head (2).

Use the following procedure to check the D dimension:


NOTE: The left and right D height difference should be no more than 10 mm (0.39 in).


1. Push the rear bumper down a minimum of 25 mm (1 in) and release. Perform this step three times.

2. Measure and record the trim height per the "Measurement Definitions" above.

3. Lift the rear bumper up a minimum of 25 mm (1 in) and release. Perform this step three times.

4. Measure and record the trim height per the "Measurement Definitions" above.

5. The true D height is the average of the measurements taken in steps 2 and 4. Refer to Trim Height Specifications

6. If these measurements are out of specifications, inspect for the following conditions: image Worn or damaged suspension components

image Collision damage


image


image


  

 

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