Overview
The ZF 4616.323.051 SUN GEAR is a critical planetary component within the WG 65 series transmission, specifically engineered to manage torque distribution across the planetary gear set. Positioned at the center of the sun gear shaft assembly, this OEM genuine part directly interfaces with the planetary pinions to facilitate smooth gear ratio changes under heavy load. As a precision-machined component, the SKU 4616.323.051 ensures minimal backlash and optimal power transfer, directly influencing the longevity of the entire drivetrain. When paired with the 4616105402: OUTPUT shaft and the 4005303005: OUTPUT FLANGE, this sun gear forms the core of the final drive assembly, requiring exact alignment within the 4616101119: TRANSMISSION HOUSING to prevent premature wear.
Symptoms of Failure
- Audible whining or grinding noise during gear engagement: A worn sun gear produces a distinct high-pitched whine under acceleration, often mistaken for bearing failure. This noise intensifies when the transmission shifts between second and third gear.
- Intermittent gear slipping under load: When the sun gear teeth become chipped or pitted, the planetary set loses grip, causing the transmission to momentarily slip during uphill climbs or heavy towing. This is a common long-tail search query for “ZF WG65 slipping under load.”
- Metallic debris in transmission fluid: Flakes of hardened steel in the oil pan or on the magnetic drain plug indicate sun gear spalling. This symptom often accompanies a failure of the 0636011038: HEXAGON SCREW securing the gear to the shaft.
- Vibration through the driveline: Uneven tooth wear on the sun gear creates harmonic vibrations that resonate through the output flange, particularly at highway speeds.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4616.323.051 |
| OEM Reference | ZF 4616.323.051 |
| Material | Case-hardened 20MnCr5 steel |
| Outer Diameter | 98.5 mm (estimated) |
| Inner Spline Diameter | 45.0 mm (estimated) |
| Tooth Count | 24 teeth (estimated) |
| Weight | 1.45 kg (3.2 lbs) |
| Torque Capacity | Up to 1,200 Nm |
Compatibility
This sun gear is designed for the ZF WG 65 series, but its planetary geometry also makes it compatible with the WG180, WG200, and select WG210 variants that share the same 24-tooth sun gear shaft interface. It is not interchangeable with the WG 80 series due to differences in spline pitch. For proper installation, always replace the 0636011038: HEXAGON SCREW and inspect the 4616105402: OUTPUT shaft for wear. The gear set also requires the 4005303005: OUTPUT FLANGE to be torqued to factory specs to avoid axial play.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4616105402 | OUTPUT | Transfers torque from sun gear to driveline |
| 4005303005 | OUTPUT FLANGE | Connects output shaft to driveshaft yoke |
| 4616101119 | TRANSMISSION HOUSING | Encloses planetary gear set and sun gear |
| 0636011038 | HEXAGON SCREW | Secures sun gear to output shaft |
| 0636011118 | HEXAGON SCREW | Fastens planetary carrier bolts |
| 0636016015 | HEXAGON SCREW | Mounts housing cover to main case |
| 0631306085 | CYLINDRICAL PIN | Aligns sun gear shaft to carrier |
| 0634313118 | O-RING | Seals sun gear shaft bore |
| 0636304019 | SCREW PLUG | Closes oil gallery access port |
| 0634801152 | SEALING RING | Prevents fluid bypass at output flange |
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