Overview
The ZF 4644.026.324 6 WG 200(555/5) Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the main gear cluster, clutch packs, and hydraulic control system into a single, ready-to-install package. As the core of the WG 200 series, it manages torque distribution across six forward speeds and one reverse speed, ensuring smooth power delivery under extreme loads. The SKU 4644.026.324 is the direct replacement for original ZF assemblies, eliminating the need for piecemeal repairs. This unit sits between the engine bellhousing and the final drive, and it is typically paired with a 4644105414: DISCONNECTION to isolate the driveline during maintenance. Proper installation also requires a 4644303409: OUTPUT FLANGE to connect to the driveshaft, and the entire assembly is secured within a 4644101222: TRANSMISSION HOUSING using 0636021083: HEXAGON SCREW fasteners.
Symptoms of Failure
- Delayed or harsh engagement when shifting from neutral to drive: Worn clutch packs inside the assembly cause a noticeable lag or a violent “clunk” as gears engage, often accompanied by a momentary loss of hydraulic pressure.
- Progressive gear slippage under load: When the transmission slips out of gear while climbing or hauling, the 4644.026.324 unit may exhibit a high-pitched whine or a sudden RPM flare without corresponding vehicle speed increase.
- External oil leaks near the bellhousing or output seal: Cracks in the assembly casing or degraded O-rings allow transmission fluid to weep, leaving puddles under the vehicle and leading to low fluid levels and eventual overheating.
- Unusual metallic grinding or knocking noises: Internal bearing failure or gear tooth damage within the assembly produces a rhythmic grinding sound that worsens with acceleration, indicating imminent catastrophic failure.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number (SKU) | 4644.026.324 |
| Assembly Type | Complete Powershift Unit (6 WG 200/555/5) |
| Overall Length | ~785 mm (estimated) |
| Dry Weight | ~195 kg (430 lbs) |
| Housing Material | High-tensile cast iron |
| OEM Reference | ZF 6 WG 200 Series |
| Input Spline Count | 21 (1.5” pitch) |
| Output Flange Bolt Pattern | 8-hole, 180 mm PCD |
| Max Input Torque | 555 Nm (estimated) |
| Fluid Capacity | ~18 liters (ZF TE-ML 03 spec) |
Compatibility
This complete assembly is engineered for the ZF WG 200 series, specifically the 6 WG 200(555/5) variant. It is directly compatible with ZF WG180, WG200, and WG210 models that share the same bellhousing pattern and input torque rating. The unit also fits select ZF 4 WG and 5 WG series transmissions when used with the appropriate adapter plate. Always verify the serial number on your existing 4644301226: TRANSMISSION HOUSING to confirm compatibility. For identification, the 0730365067: TYPE PLATE must be transferred to the new assembly. Use a 0631311009: GROOVED STUD for alignment during installation, and seal the unit with a 0634306525: O-RING at the output flange. A 4644301298: COVER PLATE protects the valve body, and a 0636305026: SCREW PLUG seals the fill port.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644105414 | DISCONNECTION | Isolates transmission from driveline for service |
| 4644303409 | OUTPUT FLANGE | Connects transmission output to driveshaft |
| 0636021083 | HEXAGON SCREW | Secures housing and cover plates |
| 4644101222 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4644301226 | TRANSMISSION HOUSING | Alternate housing variant for WG200 |
| 0730365067 | TYPE PLATE | Identification tag with serial and model |
| 0631311009 | GROOVED STUD | Alignment dowel for housing assembly |
| 4644301298 | COVER PLATE | Protects valve body and internal hydraulics |
| 0634306525 | O-RING | Seals output flange to prevent leaks |
| 0636305026 | SCREW PLUG | Closes fill and drain ports |
