Meritor RS-17144NCNN Rear Axle Bearing Preload Procedure

[MikePhua]

Introduction
The Meritor RS-17144NCNN rear axle is a critical component in heavy-duty trucks, particularly in tandem drive axle configurations. Proper bearing preload is essential for the longevity and performance of the axle. Incorrect preload can lead to premature bearing failure, excessive heat generation, and potential axle damage.
Understanding Bearing Preload
Bearing preload refers to the application of a small axial load to the bearing, ensuring that the rolling elements are in constant contact. This preload eliminates internal clearance, reducing vibration and noise, and improving the overall stiffness of the bearing assembly. However, excessive preload can increase friction and wear, while insufficient preload can lead to bearing play and instability.
Tools and Equipment Needed

• Torque wrench
  
• Dial indicator with magnetic base
  
• Adjusting nut socket
  
• Shim kit (if necessary)
  
• Bearing spacer (if necessary)
  

Procedure for Bearing Preload Adjustment

1. Preparation
   • Ensure the vehicle is securely lifted and supported.
     
   • Remove the wheel and brake components to access the axle hub.
     
   • Clean all components to prevent contamination during reassembly.
     
2. Initial Bearing Seating
   • Install the inner bearing and seal into the hub.
     
   • Place the hub assembly onto the spindle.
     
   • Install the adjusting nut and tighten it to the initial seating torque specified by Meritor.
     
   • Rotate the hub several times to seat the bearings properly.
     
3. Setting the Preload
   • Using a dial indicator, measure the end play (axial movement) of the hub.
     
   • Adjust the bearing preload by tightening or loosening the adjusting nut.
     
   • The target preload is typically between 500 and 1,000 pounds-force (lbf) for drive axles, as per SAE J2535 standards.
     
4. Final Torque and Locking
   • Once the desired preload is achieved, tighten the adjusting nut to the final torque specification.
     
   • Install the locknut or lockwasher to secure the adjusting nut in place.
     
   • If the locknut cannot be installed due to the adjusting nut being slightly off, back off the adjusting nut slightly to allow proper installation of the locknut.
     
5. Reassembly
   • Reinstall the brake components and wheel assembly.
     
   • Lower the vehicle and perform a final check for any unusual noises or play in the wheel.
     

Common Issues and Troubleshooting

• Excessive Bearing Play: If there is noticeable movement in the wheel, recheck the preload setting and adjust as necessary.
  
• Overheating: Monitor the temperature of the wheel hub during operation. Excessive heat may indicate insufficient preload or lubrication issues.
  
• Noise: Unusual noises can be a sign of incorrect preload, bearing damage, or contamination.
  

Maintenance Tips

• Regularly inspect the wheel bearings for signs of wear or damage.
  
• Ensure proper lubrication is maintained to reduce friction and wear.
  
• Follow Meritor's maintenance schedules and guidelines for axle care.
  

Conclusion
Proper bearing preload is vital for the performance and longevity of the Meritor RS-17144NCNN rear axle. By following the correct procedures and using the appropriate tools, technicians can ensure optimal operation and prevent premature failure of axle components. Always refer to Meritor's official manuals and guidelines for the most accurate and up-to-date information.