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Trifecta Pre-Adjusted Hub Assembly

The New Standard In Fast, Reliable Wheel End Installation.

The STEMCO Trifecta Pre-Adjusted Hub Assembly combines premiere STEMCO wheel end technologies with the trusted Webb® hub in a single, pre-adjusted assembly, ensuring a faster and more secure installation.  Trifecta eliminates the need to purchase, install and adjust separate wheel end components and fasteners while guaranteeing reliability.


  • Provides quick and easy installation with no bearing adjustment required.
  • Includes Zip-Torq® axle fastener featuring a unitized design with no additional clips, keepers, snap rings or screws, increasing simplicity for technicians.


  • Discover® XR is a high-performance seal that provides quick and easy installation and long life.  The seal ID includes patent-pending GlideLock technology,  significantly reducing installation force by 50% with no prelube required— the first of its kind in the industry.  
  • The Discover XR seal utilizes a 4-zone labyrinth and slinger, combined with a Defender ESP hub cap, providing unmatched contamination exclusion.
  • STEMCO manufactured precision bearings exceed ABMA performance and durability standards, and are included in OEM long-life wheel end systems.


  • Features industry-standard components manufactured by STEMCO & Webb Wheel.
  • Backed by STEMCO support nationwide, including on-site training and certification, TMC-approved procedures and a 5-year/500,000 mile parts and labor OEM warranty.

Simple Installation. Total Peace of Mind. 

Designed for fleets that value component longevity between service intervals and keeping time in the service bay as brief as possible, the Trifecta hub assembly represents the peak of durability and simplicity—the toughest, most resilient wheel end components united in an easy-to-install package.

1) Webb Wheel Hub

  • Industry-standard hubs
  • Precision machined for Trifecta
  • Ductile iron & aluminum options available
  • Over 70 years of hub expertise

2) Discover XR Seal

  • High-temperature, long-life seal
  • 4-zone labyrinth and slinger providing unmatched contamination prevention
  • GlideLock patent-pending technology - glides on, self-locking, 50% reduced installation force
  • No prelube required, eliminating the industry’s #1 cause of seal failure

3) STEMCO Manufactured Bearings

  • Exceed ABMA performance and durability standards
  • Included in OEM long-life wheel end systems

4) Defender ESP Hub Cap

  • Made from high-strength composite material
  • 100% corrosion-free 
  • ESP (Extended Service Plug) prevents contamination from entering, protects lubricant integrity  

5) Zip-Torq Axle Fastener

  • Simplified, one-piece advanced axle fastener provides fast and simple installation  
  • Self-ratcheting feature prevents back-off
  • No clips, keepers or set screws to install
  • Easy removal

6) STEMCO Spacer (patent-pending)

  • Designed for optimized lubricant flow 
  • Reduces fret corrosion between spindle and bearing mating surfaces
  • Extends spindle, bearing and seal life 

TRIFECTA Frequently Asked Questions

What is Trifecta?
Trifecta is a pre-adjusted hub assembly - STEMCO's latest commercial vehicle wheel end innovation launched in 2018. The assembly combines STEMCO's high performance Discover XR seal, the revolutionary Zip-Torq axle fastener, precision bearings, a spacer optimized for lubricant flow, and the Defender ESP hubcap, all housed in a precision machined hub. The combination of these premier components ensures mistake proof installation and less downtime; providing fleets the Trifecta of SAFETY, PERFORMANCE, AND CONFIDENCE.
What does pre-adjusted mean?
Pre-adjusted hubs eliminate the need for bearing adjustment. The precision manufactured bearings, spacer, and hub provide a fixed dimensional distance between the inner and outer bearings eliminating the need to manually adjust the bearings. A torque wrench must be used to set the axle fastener according to the pre-adjusted hub manufacturers recommended torque setting, with no backing off the nut. 
What tools do I need to install the Trifecta hub?
The only tools needed are a torque wrench and socket. See the following table for socket sizes required with Zip-Torq and Trifecta.
Where can I buy service hub assemblies or components?
Trifecta hub assemblies and components can be ordered through the independent aftermarket or original equipment dealers. For more information, contact your STEMCO distributor, local STEMCO sales person, or call 1-800-527-8492. In Canada, call 1-877-232-9111. 
What are the service intervals?
The recommended service intervals are detailed in STEMCO's Tech Tip #21 and TMC's RP 631. 
Which lubricants are approved with the Trifecta pre-adjusted hub?
The list of approved lubricants can be found in STEMCO's Tech Tip #34
Why does the spacer have holes?
The STEMCO patent pending spacer is designed with six center holes allowing lubricant to reach the mating surfaces between the interior diameter of the bearings and the spindle. The improved lubricant flow prevents fretting and associated corrosion from lubricant contamination, increasing bearing, seal and spindle life. Traditional spacers are solid and tend to block lubricant flow to the mating surfaces, potentially leading to fretting corrosion and frozen hubs.
Can I remove the spacer?
Yes, the spacer can be removed. If the spacer is removed, the bearings must be adjusted manually following TMC RP 618 procedures. Please refer to STEMCO's Tech Tip #50 for more information. 
What are half stand bearings?
Half stand bearings are precision bearings manufactured to a tighter tolerance than standard bearings. They are used in pre-adjusted hub assemblies to eliminate the need for manual bearing adjustment. STEMCO's half stand bearings can be identified with the prefix HS. Bearing cups and cones are a matched set and must be replaced as a set. Only STEMCO half stand bearings are approved for the Trifecta pre-adjusted hub assembly. 
What is GlideLock?
GlideLock is a patent pending feature on the ID (interior diameter) of the Discover XR (Extreme Runtime) seal. GlideLock significantly reduces the installation load on the seal, which helps maintain the integrity of the sealing lips during hub mounting and reduces the potential for heat generation and cocked seals. 
Does the Discover XR seal require pre-lubrication?
The Discover XR seal’s GlideLock technology is designed to perform with or without pre-lubrication, eliminating one of the industry’s leading causes of seal failure—heat.
Will the STEMCO components work in a non-Trifecta hub?
The Discover XR seal and the Zip-Torq axle fastener can be used in any commercially available wheel end. The STEMCO spacer is designed to work only in a Trifecta pre-adjusted hub assembly.
Can I use Pro-Torq or Zip-Torq axle fasteners with other Pre-adjusted hubs?
Yes. Pro-Torq and Zip-Torq can be installed with other brands of pre-adjusted hubs. However, Pro-Torq can be used with the system, replacing Zip-Torq during routine maintenance.
Are STEMCO hub caps required with the Trifecta hub?
Yes. To ensure lubricant integrity and proper venting in long life wheel end systems, and to maintain the STEMCO warranty, the Trifecta hub requires STEMCO Defender or aluminum hub caps with STEMCO's ESP or Sentinel technology. 
Can I convert the Trifecta hub to a manually adjusted hub?
Yes, the spacer can be removed and the bearings can be adjusted manually following TMC 618 procedures. Please refer to STEMCO's Tech Tip #50 for more information. 
What are the axle fastener torque specs for the Trifecta hub assembly?
The Zip-Torq axle fastener torque specifications in a Trifecta hub are 200 lb/ft for the steer and drive axles. Simply torque the nut to 200 lb / ft and spin the hub one full rotation. Repeat two additional times. Do not back off the nut.
What are the currently available applications?
The part numbers currently released include the following TRUCK applications: 5.44" offset FF (steer axle) and Long-Barrel R (drive-axle). The FF applications are a common Freightliner application. The long Barrel R is also a typical Freightliner application, as well as some PACCAR drive axle applications. 
Where can I get more information?
Please visit or call 1-800-527-8492 for more information. In Canada, call 1-877-232-9111.
For more information about the Trifecta Pre-Adjusted Hub Assembly, contact a STEMCO sales representative or find your nearest STEMCO distributor.