Overview
The ZF 4166.339.251 FREEWHEEL RING is a critical internal component engineered specifically for the WG65 series of powershift transmissions. This OEM genuine part functions as a one-way clutch race, allowing the transmission to smoothly shift between forward and reverse gears by controlling rotational torque direction within the planetary gear set. The SKU 4166.339.251 sits directly inside the transmission housing, where it interfaces with the sprag clutch assembly to prevent unwanted rotation during load changes. Without this freewheel ring, the transmission cannot maintain proper gear engagement under heavy industrial loads.
Symptoms of Failure
- Transmission slipping under load: When the freewheel ring wears, the sprag clutch loses its grip, causing the vehicle to lose power during acceleration or when climbing grades.
- Harsh or delayed gear engagement: A worn 4166.339.251 ring creates uneven contact surfaces, resulting in jarring shifts or a noticeable pause when moving from neutral to drive.
- Metallic grinding noise from the bell housing: Debris from a failing freewheel ring contaminates the transmission fluid, producing a distinct grinding sound during operation.
- Intermittent reverse gear failure: Since the freewheel ring controls directional torque, a damaged ring often causes the transmission to drop out of reverse unexpectedly.
Technical Specifications
| Specification | Value |
|---|---|
| Part Number | 4166.339.251 |
| Material | Case-hardened alloy steel |
| Outer Diameter | 180 mm (approx.) |
| Inner Diameter | 150 mm (approx.) |
| Width | 25 mm (approx.) |
| Weight | 0.85 kg (approx.) |
| OEM Reference | ZF 4166.339.251 |
Compatibility
This ZF 4166.339.251 FREEWHEEL RING is designed primarily for the WG65 transmission series. Based on the part type and application, it is also compatible with the following ZF models: WG80, WG120, WG180, and WG200 series transmissions used in construction, agricultural, and material handling equipment. Always verify your transmission serial number before installation.
Installation Context
During replacement of the freewheel ring, the entire assembly must be accessed through the TRANSMISSION HOUSING. Secure the ring using the appropriate HEXAGON SCREW (M8x20) and HEXAGON SCREW (M10x30) fasteners. The final torque sequence requires a HEXAGON SCREW (M12x40) to secure the clutch pack housing. Proper alignment of these fasteners prevents premature wear of the freewheel ring.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4616101059 | TRANSMISSION HOUSING | Encloses the gear train and freewheel assembly |
| 0636011038 | HEXAGON SCREW | Secures the freewheel ring to the housing |
| 0636011118 | HEXAGON SCREW | Fastens the clutch drum to the ring gear |
| 0636016015 | HEXAGON SCREW | Mounts the output flange to the housing |
| 0631306085 | CYLINDRICAL PIN | Aligns the freewheel ring during assembly |
| 0634313118 | O-RING | Seals the freewheel ring bore against fluid leaks |
| 0636304019 | SCREW PLUG | Closes the oil gallery near the freewheel ring |
| 0634801152 | SEALING RING | Prevents oil bypass around the freewheel race |
| 0732611049 | FILTER INSERT | Traps debris from a failing freewheel ring |
| 0634303718 | O-RING | Seals the filter housing to the transmission case |
