Overview
The ZF 4642.306.020 STOP PLATE is a precision-engineered internal component specifically designed for the WG 181 series transmission. This OEM genuine part functions as a critical mechanical stop within the planetary gear set, limiting axial movement of the clutch pack and ensuring correct gear engagement under load. Located between the TRANSMISSION HOUSING and the rotating assembly, the stop plate absorbs significant thrust forces during shifting operations. The SKU 4642.306.020 is manufactured to ZF’s original tolerances, guaranteeing a direct fit without modification. Replacing a worn stop plate restores proper clutch clearance and prevents internal contact damage that can lead to catastrophic transmission failure.
Symptoms of Failure
- Delayed or harsh gear engagement: A warped or worn stop plate allows excessive clutch pack movement, causing noticeable lag or a jarring shift feel when selecting forward or reverse gears.
- Metallic grinding noise from the transmission: As the stop plate loses its dimensional integrity, it can contact the rotating HOUSING, producing a distinct grinding sound during acceleration or deceleration.
- Intermittent gear slipping under load: Insufficient axial support from the stop plate reduces clutch clamping force, leading to momentary power loss when climbing grades or carrying heavy payloads.
- Oil contamination with metallic particles: Friction between the failed stop plate and adjacent components generates fine metal debris visible in the transmission fluid during routine inspection.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4642.306.020 |
| Material | Case-hardened steel (16MnCr5) |
| Outer Diameter | 142.0 mm |
| Inner Diameter | 68.5 mm |
| Thickness | 4.2 mm |
| Weight | 0.185 kg |
| OEM Reference | ZF 4642.306.020 |
| Surface Finish | Ground and phosphated |
Compatibility
This stop plate is primarily engineered for the ZF WG 181 series transmission, commonly found in mid-duty commercial vehicles and construction equipment. Based on its design and mounting pattern, it is also compatible with the closely related WG 180 and WG 200 series transmissions. The part interfaces directly with the THREADED BUSH that centers the assembly, and the TYPE PLATE affixed to the housing should be verified for series identification before installation. Always confirm your transmission’s serial number against the WG 181 parts catalog to ensure correct application.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101047 | TRANSMISSION HOUSING | Main structural casing enclosing the gear train |
| 4644301380 | HOUSING | Intermediate support housing for clutch components |
| 4644301189 | THREADED BUSH | Centering and retention bush for the stop plate |
| 0730365067 | TYPE PLATE | Identification plate for transmission series |
| 0631311009 | GROOVED STUD | Alignment stud for housing positioning |
| 4644301161 | COVER PLATE | Sealing cover for access port |
| 0636100621 | HEXAGON SCREW | Fastener for housing assembly |
| 0631610020 | SET SCREW | Adjustable locking screw for clearance |
| 0634801098 | SEALING RING | O-ring for fluid containment |
| 4644301117 | FIXING PLATE | Retention plate for component locking |
