Overview
The ZF 0631.306.778 CYLINDRICAL PIN is a precision-engineered locating and alignment component designed for the valve body and clutch housing assemblies within ZF WG100, WG130, and WG131 transmissions. This OEM genuine part, referenced under SKU 0631.306.778, ensures exact positioning of internal hydraulic circuits and prevents rotational movement of critical bushings. It is frequently installed alongside the 4108101031: HOUSING and the 4108303155: HOUSING to maintain structural integrity under high torque loads.
Symptoms of Failure
- Erratic gear engagement or delayed shifting: A worn or sheared cylindrical pin allows misalignment of the shift rail, causing intermittent gear slipping during acceleration.
- Hydraulic fluid seepage around the valve body: When the pin loses its press-fit tolerance, it can compromise the seal between the 0636302015: SCREW PLUG and the housing, leading to external oil leaks.
- Abnormal metallic rattling from the transmission bell housing: A loose pin can vibrate against the 0630361037: SEALING CAP, producing a distinct chatter sound at idle.
- Intermittent loss of drive in forward gears: Complete pin failure allows the clutch pack to shift out of alignment, resulting in sudden power loss under load.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number / SKU | 0631.306.778 |
| Type | Cylindrical Pin (Dowel Pin) |
| Material | Case-hardened alloy steel (DIN 6325 equivalent) |
| Diameter (Nominal) | 8 mm (h6 tolerance) |
| Length (Nominal) | 28 mm |
| Weight | Approx. 11 grams |
| OEM Reference | ZF 0631.306.778 |
| Surface Finish | Phosphate coated for corrosion resistance |
Compatibility
This cylindrical pin is a direct OEM replacement for the following ZF transmission models: WG100, WG130, and WG131. It is also commonly used in the intermediate gearbox assembly of WG180 and WG200 series transmissions where the 4108108019: INTERM.GEARBOX is present. Always verify fitment with your specific transmission serial number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4108101031 | HOUSING | Main transmission casing for WG series |
| 4108303155 | HOUSING | Rear housing adapter plate |
| 0636302015 | SCREW PLUG | Seals hydraulic ports in valve body |
| 0630361037 | SEALING CAP | Protects pin bore from debris ingress |
| 0730361010 | SEALING CAP | Alternate cap for high-temperature zones |
| 0736305007 | SCREW PLUG | Magnetic drain plug for oil pan |
| 0634801165 | SEALING RING | O-ring for pin retention bore |
| 0730365280 | TYPE PLATE | Identification plate for transmission model |
| 0631311009 | GROOVED STUD | Alignment stud for clutch housing |
| 4108108019 | INTERM.GEARBOX | Intermediate gearbox assembly |
