Overview
The ZF 4644.301.021 AXLE is a critical load-bearing component within the WG 181 series transmission, specifically engineered to support the planetary gear set and differential assembly. This OEM genuine part ensures precise rotational alignment and torque distribution across the drivetrain. The SKU 4644.301.021 is manufactured to ZF’s original specifications, guaranteeing a direct fit and long service life. It integrates directly with the TRANSMISSION HOUSING (4644101047) to maintain structural integrity under high-load conditions.
Symptoms of Failure
- Oil leaks near the axle seal: Worn axle bearings or seal surfaces cause transmission fluid to seep past the HOUSING (4644301380), leading to low fluid levels and overheating.
- Gear slipping under load: A damaged axle shaft can misalign the planetary gears, causing intermittent power loss during acceleration or hill climbs.
- Unusual whining or grinding noises: Metal-on-metal contact from a fatigued axle produces a distinct high-pitched whine that intensifies with vehicle speed.
- Vibration in the driveline: Excessive play in the axle assembly transmits vibrations through the THREADED BUSH (4644301189), felt as a rhythmic shudder in the chassis.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4644.301.021 |
| OEM Reference | ZF 4644.301.021 |
| Material | Case-hardened alloy steel (20MnCr5) |
| Weight | 4.2 kg (9.26 lbs) |
| Overall Length | 312 mm |
| Shaft Diameter | 45 mm |
| Spline Count | 28 |
| Surface Hardness | HRC 58-62 |
| Torque Capacity | 2,800 Nm |
Compatibility
This axle is designed for the ZF WG 181 series and is also compatible with WG 180, WG 200, and WG 211 transmission models. It directly replaces OEM part 4644.301.021 in all variants of the WG family. Always verify the TYPE PLATE (0730365067) on your transmission housing to confirm model and serial number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101047 | TRANSMISSION HOUSING | Encloses and supports the axle assembly |
| 4644301380 | HOUSING | Provides bearing seat and oil channel |
| 4644301189 | THREADED BUSH | Secures axle end play adjustment |
| 0730365067 | TYPE PLATE | Identifies transmission model and specs |
| 0631311009 | GROOVED STUD | Aligns housing to axle flange |
| 4644301161 | COVER PLATE | Seals axle access port |
| 0636100621 | HEXAGON SCREW | Fastens cover plate to housing |
| 0631610020 | SET SCREW | Locks threaded bush in position |
| 0634801098 | SEALING RING | Prevents oil leakage at axle interface |
| 4644301117 | FIXING PLATE | Retains axle within housing bore |
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