Overview
The ZF 4139.334.002 OUTER CLUTCH DISK is a critical friction component engineered specifically for the WG65 and select WG-series automatic transmissions. This OEM genuine part sits within the multi-plate clutch pack assembly, where it transfers torque between rotating shafts under hydraulic pressure. As the outermost disk in the clutch stack, it directly interfaces with the TRANSMISSION HOUSING to ensure precise engagement and disengagement of gear sets. The SKU 4139.334.002 is manufactured to ZF’s exacting tolerances, providing consistent friction characteristics and thermal stability under heavy-duty industrial loads.
Symptoms of Failure
- Delayed or harsh gear engagement — Worn friction material causes hesitation when shifting from neutral to drive or reverse, often accompanied by a noticeable clunk.
- Transmission slipping under load — The outer clutch disk loses its grip, causing RPM flare without corresponding vehicle speed increase, especially during uphill or loaded operation.
- Burning smell or dark fluid — Overheated friction material produces a distinct burnt odor and discolors the transmission oil, indicating imminent clutch pack failure.
- Erratic shift patterns — The transmission may hunt between gears or fail to hold a selected gear due to insufficient clamping force from the worn disk.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number (SKU) | 4139.334.002 |
| Outer Diameter | 180 mm (estimated) |
| Inner Diameter | 130 mm (estimated) |
| Thickness | 2.5 mm (estimated) |
| Material | Sintered bronze on steel core |
| Weight | 0.35 kg (estimated) |
| OEM Reference | ZF 4139.334.002 |
| Friction Coefficient | 0.10–0.12 (wet) |
Compatibility
This outer clutch disk is designed for the ZF WG65 series transmission and is also compatible with the WG 150, WG 180, WG 200, and WG 201 series. It is a direct replacement in clutch pack assemblies where the original disk has worn beyond service limits. Always verify the clutch pack stack height and inspect the HEXAGON SCREW (0636011038), HEXAGON SCREW (0636011118), and HEXAGON SCREW (0636016015) for reusability during installation. The disk is not backward-compatible with older WG models without checking the clutch drum spline count.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4616101065 | TRANSMISSION HOUSING | Encloses and supports the clutch pack assembly |
| 0636011038 | HEXAGON SCREW | Secures clutch pack retaining plate |
| 0636011118 | HEXAGON SCREW | Fastens clutch drum to hub |
| 0636016015 | HEXAGON SCREW | Mounts valve body to housing |
| 0631306085 | CYLINDRICAL PIN | Aligns clutch pack components |
| 0634313118 | O-RING | Seals hydraulic passages |
| 0636304019 | SCREW PLUG | Closes oil drain port |
| 0634801152 | SEALING RING | Prevents fluid leakage at shaft |
| 0732611049 | FILTER INSERT | Traps debris in oil circuit |
| 0634303718 | O-RING | Seals clutch piston bore |
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