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Information on Driveline Vibration Analysis and Correction

Subject:Information on Driveline Vibration Analysis and Correction

Models:2005-2007 Chevrolet Kodiak C4500/5500 Series
2005-2007 GMC TopKick C4500/5500 Series
with 4WD NV273 Transfer Case (RPO NP1)


Background
    • The NV273 transfer case is remote mounted on a bracket behind the transmission allowing for a front input drive shaft along with front and rear output drive shafts. Some radial end play on these flanges is normal as a result of the transfer case internal stack up. If the radial endplay on each flange is within the specification provided in this document, the transfer case is not to be considered a cause of excessive driveline vibration at highway speeds and does not need to be replaced.
    • In addition to excessive radial movement on the transfer case flanges, high speed driveline vibration can also result from damaged drive shafts, loose universal joints, incorrect working angles, and unbalanced driveline components. For related information, refer to Corporate Bulletin Number 06-04-21-003.
    • This document contains radial endplay measurement procedures for the input, front output, and rear output flanges found on the GM NV273 transfer case when installed in the vehicle.

Strategy Based Diagnostics
  1. Verify customer concern - Test drive the vehicle with the customer.
  2. Make preliminary checks - Complete under vehicle inspection.
  3. Perform published Diagnostic Checks - Check U-Joints. Measure working angles. Use EVA to determine if the vibration is prop-shaft related or wheel/tire.
  4. Run the engine with the front input shaft removed. If the vibration still exists then the problem is in the engine or transmission. If so, check for an out of balance automatic transmission torque converter.
  5. Call Technical Assistance if necessary.

Equipment Required
    • J-45101 Dial Indicator Set
    • Wire brush or sand paper

* If the J-45101 Dial Indicator Set is not available, use magnetic based dial indicator and follow the Alternative Dial Indicator Mounting Procedure.


Object Number: 1853228 Size: MF
(1)Input Flange
(2)Front Output Flange
(3)Rear Output Flange

Input Flange Procedure
Object Number: 1853148 Size: SH
  1. Attach a brake rotor/ball joint gauge to the circular mounting bracket on the front of the transfer case. The brake rotor/ball joint gauge must be securely attached to the transfer case bracket, not the vehicle frame or cross members.
  2. Remove any rust, dirt or debris from a small area on the outer radial surface of the input flange using sandpaper or a wire brush to ensure adequate probe contact.
  3. Position the dial indicator such that the plunger is perpendicular to the outer radial surface of the input flange.
  4. Zero out the dial indicator and compress the dial indicator probe at least 0.035" against the cleaned section of the input flange radial surface to ensure the dial indicator probe stays in contact with the surface.
  5. Without rotating the flange, apply approximately 10 to 15 pounds of force to the input flange in the opposite direction of the dial indicator and zero the dial indicator.
  6. Release the input flange and apply approximately 10 to 15 pounds of force to the input flange in the direction of the dial indicator and record the measurement. Make sure the flange does not rotate.

    7. Important: The maximum allowable endplay for the input flange is 0.032".

  7. Repeat steps 5 & 6 at least two more times to ensure the measured endplay is less than 0.032".
  8. Rotate the input flange approximately 90 degrees and repeat steps 3 through 7.

Front Output Flange Procedure
Object Number: 1853149 Size: SH
  1. Attach a brake rotor/ball joint gauge to the circular transfer case mounting bracket located on the front of the transfer case near the input flange. The brake rotor/ball joint gauge must be securely attached to the transfer case bracket, not the vehicle frame or cross members.
  2. Remove any rust, dirt or debris from a small area on the outer radial surface of the front output flange using sandpaper or a wire brush to ensure adequate probe contact.
  3. Position the dial indicator such that the plunger is perpendicular to the outer radial surface of the front output flange.
  4. Zero out the dial indicator and compress the dial indicator probe at least 0.020" against the cleaned section of the front output flange radial surface to ensure the dial indicator probe stays in contact with the surface.
  5. Without rotating the flange, apply approximately 10 to 15 pounds of force to the front output flange in the opposite direction of the dial indicator and zero the dial indicator.
  6. Release the front output flange and apply approximately 10 to 15 pounds of force to the front output flange in the direction of the dial indicator and record the measurement. Make sure the flange does not rotate.

    7. Important: The maximum allowable total endplay for the front output flange is 0.016".

  7. Repeat steps 5 & 6 at least two more times to ensure the measured endplay is less than 0.016".
  8. Rotate the front output flange approximately 90 degrees and repeat steps 3 through 7.

Rear Output Flange Procedure
Object Number: 1853150 Size: SH
  1. Attach a brake rotor/ball joint gauge to a rib on the rear retainer of the transfer case. The brake rotor/ball joint gauge must be securely attached to the transfer case rib or transfer case bolt, not the vehicle frame or cross members.
  2. Remove any rust, dirt or debris from a small area on the outer radial surface of the rear output flange using sandpaper or a wire brush to ensure adequate probe contact.
  3. Position the dial indicator such that the plunger is perpendicular to the radial surface of the rear output flange.
  4. Zero out the dial indicator and compress the dial indicator plunger at least 0.020" against the cleaned section of the rear output flange radial surface to ensure the dial indicator probe stays in contact with the surface.
  5. Without rotating the flange, apply approximately 10 to 15 pounds of force to the rear output flange in the opposite direction of the dial indicator and zero the dial indicator.
  6. Release the rear output flange and apply approximately 10 to 15 pounds of force to the rear output flange in the direction of the dial indicator and record the measurement. Make sure the flange does not rotate.

    7. Important: The maximum allowable total endplay for the rear output flange is 0.017".

  7. Repeat steps 5 & 6 at least two more times to ensure the measured endplay is less than 0.017".
  8. Rotate the rear output flange approximately 90 degrees and repeat steps 3 through 7.

Alternative Dial Indicator Mounting Procedure

Front Input & Front Output Flange

 


Object Number: 1853151 Size: SH
  1. Attach a magnetic dial indicator base to the steel circular transfer case mounting bracket located on the front of the transfer case near the input flange. The magnetic base must be securely attached to the transfer case bracket, not the vehicle frame or cross members.
  2. Follow steps 2 through 8 in the above Input and Front Output Flange procedures.

Rear Output Flange

 

  1. Clamp a dial indicator base to a rib on the rear of the transfer case housing using vise grips or a c-clamp.
  2. Follow steps 2 through 8 in the above Rear Output Flange procedure.

If one of the transfer case flanges is out of specification, then replace the roller bearing under the affected input or output flange and then remeasure.