GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 XLR 🢒 General Information 🢒 Vibration Diagnosis and Correction 🢒 Vibration Analysis - Hub and/or Axle Input

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. This test will determine the effect of turning input on the vibration.

    2.

  2. This test will determine the effect of an initial heavy torque load on the vibration.

    3.

  3. Damaged or worn wheel drive shafts may cause a noise or vibration that may be transferred into the passenger compartment.

    4.

  4. Damaged or worn wheel bearings may cause a noise or vibration that may be transferred into the passenger compartment.

    5.

  5. Damaged or worn suspension components may cause a noise or vibration that may be transferred into the passenger compartment.

    6.

  6. Damaged or worn engine, transmission, and/or exhaust mounts may cause a noise or vibration that may be transferred into the passenger compartment.

    7.

  7. Incorrect trim height may cause binding and/or interference between components that may produce a vibration.

Step

Action

Yes

No

Caution: Road test a vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.

 

1

Has the Vibration Analysis - Road Testing table been completed?

Go to Step 2

Go to Vibration Analysis - Road Testing

2

  1. Operate the vehicle at the speed of the vibration concern.
  2. While maintaining the concern speed, drive the vehicle through slow, sweeping turns--first in one direction, then in the other direction.
  3. Observe the vehicle for changes in the vibration disturbance.
  4. Select a smooth, level surface, such as an empty parking lot or a remote road.
  5. While maintaining the vehicle at the concern speed, if possible, drive the vehicle through sharp turns--360 degrees, first in one direction, then in the other direction.
  6. Observe the vehicle for changes in the vibration disturbance.

Did the characteristics of the vibration change significantly, become worse, or go away during these steps?

Go to Step 3

Go to Step 6

3

Did you hear a clicking noise and/or feel a shudder during these steps?

Go to Step 7

Go to Step 4

4

Did you hear a growling noise during these steps?

Go to Step 9

Go to Step 5

5

Did you hear a popping noise during these steps?

Go to Step 10

Go to Step 13

6

  1. With the vehicle at a stand-still, apply the regular brake and place the transmission in the lowest forward gear.

    2. Important: Do not accelerate to the point of causing the drive wheels to squeal, slip or hop--this would obscure the results of the test.

  2. Release the regular brakes and accelerate aggressively to 32 km/h (20 mph).
  3. Observe the vehicle for changes in the vibration disturbance.

Did you feel a shudder or shaking during these steps?

Go to Step 7

Go to Vibration Diagnostic Aids

7

Inspect the wheel drive shafts for damage, abnormal and/or excessive wear.

Did the inspection indicate that one or more of the wheel drive shafts needs to be replaced?

Go to Step 8

Go to Step 10

8

Replace any wheel drive shaft that was indicated by the results of the inspection. Refer to Wheel Drive Shaft Replacement in Wheel Drive Shafts.

Is the replacement complete?

Go to Step 13

--

9

  1. Inspect the wheel bearings for wear and/or damage. Refer to Wheel Bearings Diagnosis in Suspension General Diagnosis.
  2. Replace any of the wheel bearings found to be worn and/or damaged. Refer to the appropriate procedure:
    3. •  Front Wheel Bearing and Hub Replacement in Front Suspension

Did you find and correct a condition?

Go to Step 13

Go to Vibration Diagnostic Aids

10

  1. Inspect the following suspension components for wear, damage, looseness and/or possible contact with other vehicle components:
    2. • Shock absorbers
    • Springs
    • Bushings
    • Insulators
  2. Replace any of the suspension components found to be worn, damaged, loose and/or contacting other vehicle components.

Did you find and correct a condition?

Go to Step 13

Go to Step 11

11

  1. Inspect the powertrain mounts for the following:
    2. • Loose and/or missing fasteners
    • Improper alignment
    • Cracked, dry-rotted, and/or oil-soaked insulators
    • Twisted, broken, torn, and/or collapsed insulators
    • Bent, twisted, and/or deformed brackets
  2. Replace powertrain mounts as necessary. Refer to the following procedures:
    3. •  Engine Mount Replacement - Left Side in Engine Mechanical - 4.6L (LH2)
    •  Engine Mount Replacement - Right Side in Engine Mechanical - 4.6L (LH2)
    •  Transmission Mount Replacement in Rear Drive Axle
  3. Inspect the exhaust system components for the following:
    4. • Loose and/or missing fasteners
       - Heat Shields
       - Joints and/or couplings:
       - Nuts, bolts, studs, clamps, straps
       - Bracket and/or insulator mounting
    • Inadequate clearance to body and/or chassis components
    • Inspect with the exhaust system both COLD and HOT; in NEUTRAL, FORWARD and REVERSE gears
    • Improper alignment
    • Disconnected and/or missing insulators
    • Cracked, dry-rotted, and/or oil-soaked insulators
    • Stretched, twisted, broken, torn, and/or collapsed insulators
    • Bent, twisted, cracked, and/or deformed brackets
  4. Repair, replace, and/or realign exhaust system components as necessary.

Did you find and correct a condition?

Go to Step 13

Go to Step 12

12

Inspect the vehicle trim height and adjust as necessary. Refer to Trim Height Specifications in Suspension General Diagnosis.

Did you find and correct a condition?

Go to Step 13

Go to Vibration Diagnostic Aids

13
  1. Install or connect any components that were removed or disconnected during diagnosis.
  2. Perform the Vibration Analysis - Road Testing table. Refer to Vibration Analysis - Road Testing .

Is the vibration still present?

Go to Step 2

System OK