Upgrading a 1968 Fruehauf Tiltbed Trailer: Converting from 5-Lug to 8-Lug Hubs

[MikePhua]

Introduction
The 1968 Fruehauf deckover tiltbed trailer, rated at 20,000 lbs with dual axles and single wheels, originally came equipped with Dexter 8-133 rim clamp 5-lug 14.5" hubs. Over time, these hubs may have limitations in terms of strength and compatibility with modern components. Upgrading to 8-lug hubs allows for the use of 16" or 17.5" wheels, accommodating heavier loads and enhancing safety.
Understanding the Existing Setup

• Axle Identification: The Dexter 8-133 axle is known for its 5-lug configuration and 14.5" wheels. To ensure compatibility with new hubs, it's crucial to verify the axle's specifications, including the spindle dimensions and bearing sizes.
  
• Hub Dimensions: The existing 5-lug hubs have a bolt circle diameter (BCD) of 5x4.5" and are designed for 14.5" wheels. Upgrading to 8-lug hubs typically involves a BCD of 8x6.5" or 8x7.25", which are standard for 16" and 17.5" wheels.
  

Selecting the Right 8-Lug Hubs
When considering an upgrade, it's essential to choose hubs that match the existing axle's specifications. Several aftermarket options are available:

1. PTP HT799RC Fruehauf ProPar Trailer Hub: This outboard mount hub includes studs for steel wheels and is designed for 16.5" brake drums. It features a bolt circle diameter of 11.25" and is compatible with 8-lug wheels.
   
2. PTP HT799RD Fruehauf ProPar Trailer Hub: Similar to the HT799RC, this hub is designed for aluminum wheels and also supports 16.5" brake drums. It includes studs and has a bolt circle diameter of 11.25".
   
3. HT818RCPTP Trailer Hub: This hub is designed to convert cast spoke or inboard mount hubs to outboard hub-piloted configurations, making it suitable for upgrading older trailers.
   

Installation Considerations

• Bearing Compatibility: Ensure that the new hubs are compatible with the existing bearings. For instance, the HT799RC and HT799RD hubs use the HM518445 bearing cone and HM518410 bearing cup. Verify that these match your current setup.
  
• Brake Drum Compatibility: The selected hubs are designed for 16.5" brake drums. Confirm that your trailer's brake system can accommodate this size.
  
• Wheel Compatibility: Upgrading to 8-lug hubs allows for the use of 16" or 17.5" wheels. Ensure that the new wheels are compatible with the selected hubs and meet the trailer's load requirements.
  

Conclusion
Upgrading the hubs on a 1968 Fruehauf tiltbed trailer from 5-lug to 8-lug configurations enhances the trailer's load capacity and safety. By carefully selecting compatible hubs, bearings, and wheels, and ensuring proper installation, you can significantly improve the trailer's performance and longevity.