Buick Regal: Suspension General Diagnosis

SPECIFICATIONS

TRIM HEIGHT SPECIFICATIONS

Trim Height Specifications (P-R Height) - Hatchback

NOTE: For 0% option vehicles add 1 mm to front and rear suspension values.

For 100% option vehicles subtract 4 mm from front suspension values and substract 3 mm from rear suspension values.

Trim Height Specifications (P-R Height) - Station Wagon

NOTE: For 0% option vehicles add 2 mm to front and rear suspension values.

For 100% option vehicles subtract 4 mm from front suspension values and substract 6 mm from rear suspension values.

DIAGNOSTIC INFORMATION AND PROCEDURES

SYMPTOMS - SUSPENSION GENERAL DIAGNOSIS

NOTE: 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:

• Front Suspension Description and Operation
• Rear Suspension Description and Operation

Visual/Physical Inspection

• Inspect for aftermarket devices which could affect the operation of any of the suspension subsystems.
• Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
• Inspect for proper tire size and inflation pressure.

Symptom List

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

• Body Leans or Sways in Corners
• Memory Steer
• Suspension Strut and Shock Absorber Testing - On Vehicle
• Noise Diagnosis - Front Suspension
• Noise Diagnosis - Rear Suspension
• Torque Steer
• Vehicle Leads/Pulls

RIDE DIAGNOSIS

VEHICLE LEADS/PULLS

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 straight path.

NOTE: Vehicles will tend to lead/pull in the direction of the road slope as part of normal operation.

BODY LEANS OR SWAYS IN CORNERS

SUSPENSION BOTTOMS

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.

TORQUE STEER

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

MEMORY STEER

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.

NOISE DIAGNOSIS - FRONT SUSPENSION

DEFINITION: Any noise emitted from the front of the vehicle that is induced by VEHICLE SPEED or DRIVING TERRAIN as related to the front suspension.

NOISE DIAGNOSIS - REAR SUSPENSION

Special Tools

CH-39570 Chassis Ear

For equivalent regional tools, refer to Special Tools.

DEFINITION: Any noise emitted from the rear of the vehicle that is induced by VEHICLE SPEED or DRIVING TERRAIN as related to the rear suspension.

BALL JOINT INSPECTION

Special Tools

J 8001 Dial Indicator Set

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

2. Clean and inspect the ball joint seal for cuts or tears. If the ball joint seal is damaged, replace the lower control arm. Refer to Lower Control Arm Replacement.

3.

Install the J 8001 set (1) in a way to measure vertical lash in the ball joint.

CAUTION: Do not pry in such a way that the ball joint seal is contacted. Damage to the seal may result.

4. Gently lift or pry the suspension to induce ball joint movement.

5. If the dial indicator indicates a reading greater than 0.5 mm (0.02 in), replace the lower control arm.

Refer to Lower Control Arm Replacement.

SUSPENSION STRUT AND SHOCK ABSORBER TESTING - ON VEHICLE

WHEEL BEARINGS DIAGNOSIS

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:

• Set the tire pressure to the specifications shown on the certification label.

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

• Check the fuel level. Add additional weight if necessary to simulate a full tank.
• Make sure the passenger and rear compartments are empty, except for the spare tire, if equipped.
• Make sure the vehicle is on a flat and level surface, such as an alignment rack.
• Check that all the vehicle doors are securely closed.
• Check that the vehicle hood and rear deck lids are securely closed.
• Check for installed after market accessories or modifications that could affect trim height measurement:
  • Larger or Smaller than production wheels and tires.
  • Lifting or Lowering Kits
  • Wheel Opening Flares or Ground Affects

Measuring the P and R Dimension

Measurement Definitions

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

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

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

NOTE: The left and right P and R height differences should be no more than 10 mm (.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 & 4.

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

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

CH-39570

J 39570

Chassis Ear

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