Overview
The ZF 4475.280.099 SCREW PLUG is a precision-engineered sealing component designed for the lubrication and hydraulic circuits within ZF WG100, WG130, and WG131 transmission assemblies. This OEM genuine part functions as a threaded closure point, preventing fluid loss and maintaining system pressure within the valve body and housing channels. The SKU 4475.280.099 is manufactured to exact ZF tolerances, ensuring a secure fit against vibration and thermal expansion. It is typically installed in the lower sump area or side ports of the transmission, directly interfacing with the 4143101022: HOUSING and the 4143301044: HOUSING to seal critical fluid passages.
Symptoms of Failure
When the 4475.280.099 screw plug degrades or is improperly torqued, operators may encounter these specific failure modes:
- External oil seepage around the plug head – A slow drip or wet film on the transmission housing, often mistaken for a gasket failure.
- Erratic shift quality or delayed engagement – Loss of hydraulic pressure due to a compromised seal can cause gear hunting or harsh shifts.
- Visible thread damage or cross-threading – Over-torquing or corrosion can strip the threads, leading to a loose plug and eventual fluid evacuation.
- Contaminated transmission fluid – A failed plug allows debris ingress, accelerating wear on internal components like the 0631329135: SPRING PIN and valve body.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4475.280.099 |
| Type | Hexagon socket screw plug |
| Thread Size | M18 x 1.5 (estimated) |
| Overall Length | 22 mm |
| Head Diameter | 24 mm |
| Material | Steel, zinc-plated |
| Weight | 0.04 kg |
| OEM Reference | 4475.280.099 |
Compatibility
This screw plug is specifically validated for the following ZF transmission models: WG100, WG130, and WG131. It may also be suitable for select WG180 and WG200 variants where the port thread matches M18 x 1.5. For applications requiring a different sealing profile, consider the 0636302014: SCREW PLUG which shares a similar function but with a modified thread pitch. Always verify housing compatibility with the 4143301053: CONNECTING PART when retrofitting.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4143101022 | HOUSING | Main transmission casing |
| 4143301044 | HOUSING | Valve body housing section |
| 0631329135 | SPRING PIN | Retains shift fork or detent |
| 0636302014 | SCREW PLUG | Alternate plug for different ports |
| 0634801057 | SEALING RING | Copper washer for plug seal |
| 4143301053 | CONNECTING PART | Hydraulic line adapter |
| 0636100600 | CAP SCREW | Fastener for cover plates |
| 0636101024 | CAP SCREW | High-strength fastener |
| 0730365159 | TYPE PLATE | Identification label |
| 0631311009 | GROOVED STUD | Alignment dowel |
