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Adjustment Procedure Using Oscilloscope

WARNING: This page is about a different car, the 2016 GMC Acadia, 2016 Chevrolet Traverse, and 2016 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:

Do not depress the brake pedal with the brake rotors and/or the brake drums removed, or with the brake calipers repositioned away from the brake rotors, or damage to the brake system may result.

The balance procedure is integrated into the CH-51450-NVH  Oscilloscope Diagnostic Kit (w/NVH) in its Driveline Balancing utility. There are two methods for balancing:

The following is an overview of the two driveline balancing methods.

Hose Clamp Method

  1. Raise and support the vehicle; ensure that the drive axle or axles are supported at ride height - vehicle body supported by suspension components. Refer to Lifting and Jacking the Vehicle .
  2. Connect the Oscilloscope to the USB port of the computer using the blue USB cable, CH-51450-M1106  .
  3. Connect the Accelerometer CH-51450-TA183  to the NVH Interface CH-51450-TA148  .
  4. Connect the NVH Interface to Channel B of the Oscilloscope using the CH-51450-TA098  BNC to BNC cable.
    5. Fig 1: Accelerometer
    GM3765870Courtesy of GENERAL MOTORS COMPANY
  5. Mount the Accelerometer (1) to a suitable surface on the vehicle differential. If the differential case is non-ferrous, a steel washer can be glued on the differential case in order to secure the magnetic Accelerometer.
    6. Fig 2: Optical Sensor And Interface
    GM3765871Courtesy of GENERAL MOTORS COMPANY
  6. Connect the Optical Sensor CH-51450-TA186  (1) to the Optical Sensor Interface CH-51450-TA185  (2).
  7. Connect the Optical Sensor Interface to Channel D of the Oscilloscope using the CH-51450-TA098  BNC to BNB cable.
    8. Fig 3: Magnetic Mounting Fixture
    GM3765872Courtesy of GENERAL MOTORS COMPANY
  8. Mount the Magnetic Mounting Fixture CH-51450-TA187  (1) to a suitable surface on the vehicle underbody.
  9. Place a 1/2 inch strip of reflective tape to the propeller shaft.
  10. Focus the laser (2) on the reflective tape.
  11. Install 2 hose clamps side by side to the propeller shaft near the differential, on an area clear of any factory balance weights.
  12. Mark the excess band on the hose clamps.
  13. Remove the hose clamps and trim the excess from the hose clamp bands.
  14. Enter the weight of the hose clamp, in grams, into the balancing software.
  15. To determine the weight of the hose clamp, use the following:
    • Cut the screw body off of the clamp, even with end of the screw.
    • Weigh the screw body on a gram scale (14 g is typical).
  16. Measure the circumference of the propeller shaft near the hose clamps using the supplied ruler and enter that figure, in millimeters, into the balancing software.
  17. Alternatively, enter the diameter, in millimeters, of the propeller shaft into the balancing software.
  18. Before beginning the test, inspect for the following:
    • The vehicle is properly supported. Refer to Lifting and Jacking the Vehicle .
    • Remove any rocks or debris embedded in the tire treads.
    • Secure all test leads clear of rotating components.
    • Disable the ABS and traction control, if equipped.
    • Turn OFF the A/C, and any other accessories.
  19. Determine a suitable propeller shaft speed.
    • Start the engine.
    • Place the transmission in the highest forward gear.
    • Run the engine to highway speed, typically 104-112 km/h (65-70 mph).
    • When the RPM can be held stable for longer than 3 seconds, the balancing software will capture and enter the propeller shaft speed.
    • Alternatively, click the Edit Manually check box and enter the desired propeller shaft speed.
    • Place the transmission in NEUTRAL.
    • Turn OFF the engine.
  20. Begin the propeller shaft balancing.

    Initial Run 

    Fig 4: 0 mm Mark
    GM3765873Courtesy of GENERAL MOTORS COMPANY
    1. Place the first clamp on the propeller shaft near the differential.
    2. Clearly mark the location of the clamp as reference for all remaining measurements.
    3. Label the mark (1) as 0 mm.
    4. Measure the distance specified by the software and place the second clamp next to the first clamp.
    5. Measure the distance specified by the software and place the second clamp next to the first clamp.
    6. Press the green Initial Run button to start the test.
    7. Start the engine.
    8. Place the transmission in the highest forward gear.
    9. Accelerate the engine until the required speed is reached.
    10. The RPM graph will highlight green when the RPM is within the specified range, and data will only be gathered while within this range.
  21. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  22. Perform the first calibration run.

    Calibration Run 1

    1. Place both hose clamps at the 0 mm label.
    2. Press the green Calibration Run 1 button.
    3. Start the engine.
    4. Place the transmission in the highest forward gear.
    5. Accelerate the engine until the required speed is reached.
  23. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  24. Perform the second calibration run.

    Calibration Run 2

    1. Measuring in the direction of forward propeller shaft rotation, mark the point as indicated on the balancing software.
    2. Place both hose clamps at this mark.
    3. Press the green Calibration Run 2 button.
    4. Start the engine.
    5. Place the transmission in the highest forward gear.
    6. Accelerate the engine until the required speed is reached.
  25. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  26. Perform the third calibration run.

    Calibration Run 3

    1. Measuring from the 0 mm mark in the direction of forward propeller shaft rotation, mark the point as indicated on the balancing software.
    2. Place both hose clamps at this mark.
    3. Press the green Calibration Run 3 button.
    4. Start the engine.
    5. Place the transmission in the highest forward gear.
    6. Accelerate the engine until the required speed is reached.
  27. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  28. Perform the final propeller shaft balancing.

    Final Balance

    1. Measure and mark the locations as indicated on the balancing software.
    2. Place the hose clamps at these locations.
    3. Press the green Verification button.
    4. Start the engine.
    5. Place the transmission in the highest forward gear.
    6. Accelerate the engine until the required speed is reached.
  29. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  30. The software will display the final imbalance.
  31. If the imbalance exceeds the minimum requirement, the software will recommend removing the rear tire and wheel assemblies and, after securing the brake rotors or brake drums, restarting the test.

Pinion Flange Method

  1. Raise and support the vehicle; ensure that the drive axle or axles are supported at ride height - vehicle body supported by suspension components. Refer to Lifting and Jacking the Vehicle .
  2. Connect the Oscilloscope to the USB port of the computer using the blue USB cable, CH-51450-M1106  .
  3. Connect the Accelerometer CH-51450-TA183  to the NVH Interface CH-51450-TA148  .
  4. Connect the NVH Interface to Channel B of the Oscilloscope using the CH-51450-TA098  BNC to BNC cable.
    5. Fig 5: Accelerometer
    GM3765875Courtesy of GENERAL MOTORS COMPANY
  5. Mount the Accelerometer (1) to a suitable surface near the front of the differential. If the surface is non-ferrous, a steel washer can be glued to the surface in order to secure the magnetic Accelerometer.
    6. Fig 6: Optical Sensor And Interface
    GM3765871Courtesy of GENERAL MOTORS COMPANY
  6. Connect the Optical Sensor CH-51450-TA186  (1) to the Optical Sensor Interface CH-51450-TA185  (2).
  7. Connect the NVH Interface to Channel D of the Oscilloscope using the CH-51450-TA098  BNC to BNB cable.
    8. Fig 7: Magnetic Mounting Fixture
    GM3765876Courtesy of GENERAL MOTORS COMPANY
  8. Mount the Magnetic Mounting Fixture CH-51450-TA187  (1) to a suitable surface on the vehicle underbody.
  9. Place a 1/2 inch strip of reflective tape to the propeller shaft.
  10. Focus the laser on the reflective tape.
  11. Measure the circumference of the pinion flange bolt circle and enter that figure, in millimeters, into the balancing software.
  12. Alternatively, enter the diameter, in millimeters, of the pinion flange into the balancing software.
    13. Fig 8: Numbering Pinion Flange Bolts And/Or Studs
    GM3765879Courtesy of GENERAL MOTORS COMPANY
  13. Enter the number of pinion flange bolts into the balancing software.
  14. Number the pinion flange bolts and/or studs (1) in the direction of propeller shaft rotation.
  15. Before beginning the test, inspect for the following:
    • The vehicle is properly supported. Refer to Lifting and Jacking the Vehicle .
    • Remove any rocks or debris embedded in the tire treads.
    • Secure all test leads clear of rotating components.
    • Disable the ABS and traction control, if equipped.
    • Turn OFF the A/C, and any other accessories.
  16. Determine a suitable propeller shaft speed.
    • Start the engine.
    • Place the transmission in the highest forward gear.
    • Run the engine to highway speed, typically 104-112 km/h (65-70 mph).
    • When the RPM can be held stable for longer than 3 seconds, the balancing software will capture and enter the propeller shaft speed.
    • Alternatively, click the Edit Manually check box and enter the desired propeller shaft speed.
    • Place the transmission in NEUTRAL.
    • Turn OFF the engine.
  17. Begin balancing the propeller shaft.

    Initial Run

    1. Press the green Initial Run button to start the test.

      An initial measurement of the propeller shaft will be taken.

    2. Start the engine.
    3. Place the transmission in the highest forward gear.
    4. Accelerate the engine until the required speed is reached.
    5. The RPM graph will highlight green when the RPM is within the specified range, and data will only be gathered while within this range.
  18. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  19. Perform the first calibration run.

    Calibration Run 1

    1. Place 4.5 g of weight at location 1 by stacking 3 of the balancing weights (1.5 g each). The weights may be affixed to the front or the rear of the pinion flange.
    2. Press the green Calibration Run 1 button.
    3. Start the engine.
    4. Place the transmission in the highest forward gear.
    5. Accelerate the engine until the required speed is reached.
  20. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  21. Perform the second calibration run.

    Calibration Run 2

    1. Remove the balancing weights from location 1.
    2. Install the balancing weights at location 3.
    3. Press the green Calibration Run 2 button.
    4. Start the engine.
    5. Place the transmission in the highest forward gear.
    6. Accelerate the engine until the required speed is reached.
  22. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  23. Perform the third calibration run.

    Calibration Run 3

    1. Remove the balancing weights from location 3.
    2. Install the balancing weights at location 5.
    3. Press the green Calibration Run 3 button.
    4. Start the engine.
    5. Place the transmission in the highest forward gear.
    6. Accelerate the engine until the required speed is reached.
  24. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine.
  25. Perform the final propeller shaft balancing.

    Final Balance

    1. Remove the balancing weights from location 5.
    2. Install the balancing washers to the location(s) indicated by the balancing software.
    3. Press the green Verification button.
    4. Start the engine.
    5. Place the transmission in the highest forward gear.
    6. Accelerate the engine until the required speed is reached.
  26. When the Complete % bar graph is filled, place the transmission in NEUTRAL and turn OFF the engine..
  27. The software will display the final imbalance.
  28. If the imbalance exceeds the minimum requirement, the software will recommend removing the rear tire and wheel assemblies and, after securing the brake rotors or brake drums, and restarting the test.
  29. If the test is to be restarted, remove all of the balancing weights.
  30. The test can then be restarted by either of the following methods:
    • Press the Initial Run button to restart the test.
    • Press the Balancing button to enter the test through the setup wizard.
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