Overview
The ZF 4616.305.055 CYLINDER for WG65 is a precision-engineered hydraulic actuation component designed to manage clutch pack engagement and disengagement within the WG series transmission valve body. This OEM genuine part, identified by SKU 4616.305.055, functions as a critical pressure vessel that converts hydraulic force into linear mechanical motion, directly influencing shift timing and torque transfer. It sits within the main control housing assembly, working in concert with the 4616101089: TRANSMISSION HOUSING to maintain sealed fluid pathways. The cylinder’s internal bore and piston interface must remain free of scoring to prevent cross-port leakage that degrades shift quality.
Symptoms of Failure
- Delayed or harsh gear engagement: When the cylinder wall becomes worn or scored, hydraulic pressure bleeds past piston seals, causing noticeable lag when shifting from Neutral to Drive or Reverse.
- Intermittent transmission slipping under load: A failing 4616.305.055 cylinder cannot maintain clamping force on clutch packs, resulting in momentary RPM flare during uphill climbs or heavy towing.
- External hydraulic fluid seepage: Cracks in the cylinder body or degraded sealing surfaces allow ATF to escape, often pooling near the bellhousing or valve body cover.
- Erratic shift patterns in cold weather: Thermal expansion differences between a worn cylinder and its mating 0636011038: HEXAGON SCREW fasteners can create inconsistent clearances, worsening shift quality at low ambient temperatures.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4616.305.055 |
| Material | High-tensile aluminum alloy with hard-anodized bore |
| Overall Length | 142 mm (estimated) |
| Bore Diameter | 38 mm (estimated) |
| Dry Weight | 0.48 kg (1.06 lbs) |
| OEM Reference | ZF 4616.305.055 |
| Seal Compatibility | Requires 0634313118: O-RING and 0634801152: SEALING RING |
| Fastener Torque | Use 0636011118: HEXAGON SCREW (M8x25, 25 Nm) and 0636016015: HEXAGON SCREW (M10x30, 45 Nm) |
| Alignment Aid | 0631306085: CYLINDRICAL PIN (2x required) |
| Fluid Port Seal | 0636304019: SCREW PLUG with integrated sealing washer |
Compatibility
This cylinder is engineered for the ZF WG65 series, but its hydraulic circuit design also supports select models in the WG180 and WG200 families when used with the correct valve body spacer plate. The 4616.305.055 is directly interchangeable with earlier WG65 variants (serial numbers after 2017). For WG180 applications, verify that the 0732611049: FILTER INSERT and 0634303718: O-RING are updated to match the cylinder’s flow rate. Always cross-reference your transmission’s data plate before ordering, as some WG200 units use a longer-stroke variant.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4616101089 | TRANSMISSION HOUSING | Encloses gear train and valve body |
| 0636011038 | HEXAGON SCREW | Secures cylinder to valve body |
| 0636011118 | HEXAGON SCREW | Fastens cylinder end cap |
| 0636016015 | HEXAGON SCREW | Mounts cylinder to housing |
| 0631306085 | CYLINDRICAL PIN | Aligns cylinder bore |
| 0634313118 | O-RING | Seals piston-to-cylinder interface |
| 0636304019 | SCREW PLUG | Closes hydraulic test port |
| 0634801152 | SEALING RING | Prevents fluid bypass at cylinder base |
| 0732611049 | FILTER INSERT | Traps debris entering cylinder circuit |
| 0634303718 | O-RING | Seals filter insert housing |
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