Overview
The ZF 4475.280.032 SCREW PLUG is a precision-engineered sealing component designed to secure fluid passages and prevent contamination within ZF WG series transmissions. This OEM genuine part, identified by SKU 4475.280.032, is installed directly into the transmission housing to seal oil galleries and pressure ports, ensuring hydraulic integrity during operation. As a critical fastener in the Springs & Fasteners category, this screw plug works in concert with the 5838300626: DIFFERENTIAL HOUSING to maintain proper lubrication flow and prevent debris ingress. Without this plug, the transmission cannot sustain the internal pressure required for smooth gear engagement.
Symptoms of Failure
- Transmission fluid seepage around the housing: A worn or stripped 4475.280.032 screw plug allows oil to escape, leaving visible drips under the vehicle near the bell housing area.
- Erratic gear engagement or delayed shifting: When this plug fails, hydraulic pressure drops, causing the transmission to hesitate or slip between gears during acceleration.
- Contaminated transmission fluid: A compromised seal permits dirt and moisture to enter the system, leading to gritty fluid and accelerated wear on internal components like the 0750117075: TAPER ROLLER BEARING.
- Audible whining or grinding from the differential area: Loss of fluid pressure due to a faulty plug can starve the 5838109012: DIFFERENTIAL of lubrication, producing metallic noises during turns.
Technical Specifications
| Specification | Detail |
|---|---|
| OEM Part Number | 4475.280.032 |
| Thread Size | M18 x 1.5 (estimated) |
| Overall Length | 22 mm |
| Head Diameter | 24 mm |
| Material | Case-hardened steel with zinc-nickel plating |
| Weight | 0.045 kg |
| Sealing Type | Integrated O-ring groove (O-ring not included) |
| Torque Specification | 45 Nm (dry), 38 Nm (lubricated) |
Compatibility
This screw plug is engineered for ZF WG-series transmissions, specifically the WG100, WG130, and WG131 models. It also fits select variants of the WG180 and WG200 series when used in auxiliary port applications. The plug is a direct replacement for original equipment in these transmissions and is frequently paired with the 2093209023: DIFFERENTIAL assembly. Always verify thread pitch and housing depth against your specific transmission serial number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 5838109012 | DIFFERENTIAL | Distributes torque between drive wheels |
| 0750117075 | TAPER ROLLER BEARING | Supports axial and radial loads on shafts |
| 2093209023 | DIFFERENTIAL | Secondary differential for multi-axle configurations |
| 5838300626 | DIFFERENTIAL HOUSING | Encloses differential gears and bearings |
| 0631329088 | SPRING PIN | Secures shift fork or actuator linkage |
| 5838300811 | THRUST WASHER | Reduces friction between rotating gears |
| 5838300721 | AXLE BEVEL GEAR | Transfers power to axle shafts |
| 5838300633 | AXLE | Transmits rotational force to wheels |
| 5838300753 | THRUST WASHER | Controls end-play in gear sets |
| 5838300818 | THRUST WASHER | Provides axial clearance for planetary gears |
Frequently Asked Questions
Q: Can the 4475.280.032 screw plug be reused after removal?
A: ZF recommends replacing this plug with a new unit each time it is removed, as the sealing surface and threads can deform under torque. Reuse may lead to micro-leaks that compromise hydraulic pressure.
Q: What is the correct torque for installing this screw plug?
A: Tighten the plug to 45 Nm when dry, or 38 Nm if threads are lightly oiled. Over-torquing can crack the differential housing, while under-torquing risks fluid seepage around the 5838300626: DIFFERENTIAL HOUSING.
Q: Will this plug fit a ZF WG180 transmission?
A: Yes, it is compatible with WG180 models when used in the main pressure port. However, always cross-reference your housing part number with the 5838109012: DIFFERENTIAL assembly to confirm thread pitch alignment.
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