Can You Still Repair a Clark 10054 Transmission with a Spicer Input Flange

[MikePhua]

Yes, but it requires ingenuity and local expertise. The Clark 12.2 MHR transmission used in the 1997 SkyTrak 10054 telehandler is no longer supported by JLG or SkyTrak for certain components, including the Spicer input/output flange. However, with careful measurement and collaboration with machinists or driveline specialists, the flange can be repaired or replaced using Spicer’s legacy catalogs and aftermarket solutions.
Clark Transmission and SkyTrak Integration
Clark transmissions were widely used in material handlers and industrial vehicles throughout the 1980s and 1990s. The 12.2 MHR model is a three-speed powershift unit designed for high torque and continuous duty. In the SkyTrak 10054, this transmission interfaces with a driveline shaft via a Spicer-style flange, which connects to a universal joint (U-joint) and transfers power from the engine to the transmission.
SkyTrak, originally an independent telehandler manufacturer, was acquired by JLG in the early 2000s. Since then, parts support for older models has gradually diminished, especially for components not manufactured directly by JLG.
Terminology Notes

• Spicer Flange: A driveline component manufactured by Dana Spicer, used to connect shafts via U-joints.
  
• U-joint Cap Stops: Raised edges or grooves that hold the bearing caps of the universal joint in place.
  
• Input Shaft Bearing: A bearing inside the transmission that supports the rotating input shaft; vulnerable to vibration and misalignment.
  
• High-Speed Shaft: A driveline shaft operating at engine RPM, requiring precise balance and alignment.
  

Common Failure Symptoms and Risks

• Worn cap stops on the flange allow the U-joint to shift, causing vibration.
  
• Excessive vibration at idle can damage the input shaft bearing and lead to transmission failure.
  
• Discontinued OEM parts force owners to seek alternative repair paths.
  

In one case, a recycler in Alaska noticed severe vibration and traced it to a worn flange. With no support from JLG or SkyTrak, he consulted a local machinist who had access to Spicer catalogs and proposed measuring the flange to identify a compatible replacement or fabricate a new one.
Repair and Replacement Strategies

• Measure the flange dimensions precisely: bolt pattern, pilot diameter, spline count, and cap stop depth.
  
• Consult Spicer’s industrial driveline catalogs, which list hundreds of flange types by dimension and application.
  
• Use a driveline shop to source or fabricate a new flange, possibly converting to a more common U-joint size.
  
• If replacement is impossible, weld and machine the existing flange carefully:
  

• Tack weld the cap stops to restore fit.
  
• Use water cooling to protect seals and bearings.
  
• Ensure concentricity and balance to avoid vibration.
  

Transmission Identification for Parts Lookup

• Model: Clark 12.2 MHR
  
• Serial: WBEA 435764
  
• SkyTrak part number: 8841025
  

These identifiers allow transmission specialists to cross-reference internal components, even if the flange itself is not listed.
Additional Considerations

• Inspect the flywheel coupling during reassembly; early SkyTrak designs had coupling failures that were later redesigned.
  
• Use a magnetic drain plug to monitor for metal debris after repair.
  
• Balance the driveline shaft if any welding or machining is performed.
  

Conclusion
Repairing a Clark transmission with a worn Spicer flange is a challenge, but not a dead end. With accurate measurements, access to legacy catalogs, and skilled machining, the flange can be restored or replaced. In the world of aging telehandlers, resourcefulness often replaces factory support—and every vibration tells a story worth solving.