Overview
The ZF 0636.015.038 HEXAGON SCREW is a critical fastening component engineered for the WG100, WG130, and WG131 transmission series. This OEM genuine part secures internal assemblies within the transmission housing, ensuring precise alignment of planetary gear sets and bearing covers. As a high-tensile fastener, it withstands extreme torque loads and thermal cycling. The SKU 0636.015.038 is specifically designed to maintain clamping force in the valve body and clutch pack regions, preventing micro-movement that can lead to premature wear. When replacing this screw, it is common to also inspect the 4108101112: HOUSING and 4108201177: HOUSING for cracks or distortion, as these components share the same load path.
Symptoms of Failure
- Transmission fluid seepage around bolt heads: A loose or fatigued 0636.015.038 hexagon screw can compromise the seal between the 4108301304: BEARING COVER and the main case, leading to visible oil drips.
- Intermittent gear slippage under load: When this fastener loses torque, clutch pack clearance increases, causing delayed engagement or slipping during acceleration.
- Metallic rattling from the transmission pan: A broken hexagon screw may fall into the sump, creating debris that damages the 0636302056: SCREW PLUG or valve body passages.
- Hard shifting or erratic shift timing: Insufficient clamping force on the separator plate alters hydraulic pressure, resulting in harsh upshifts or delayed downshifts.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 0636.015.038 |
| Type | Hexagon Screw (Socket Head Cap Screw) |
| Thread Size | M8 x 1.25 (estimated) |
| Length | 30 mm (estimated) |
| Material | Alloy Steel, 10.9 Grade |
| Surface Treatment | Zinc-Nickel Plating |
| Weight | 12 grams (estimated) |
| OEM Reference | ZF 0636.015.038 |
| Torque Spec | 25 Nm + 90° (factory spec) |
Compatibility
This hexagon screw is a direct fit for ZF WG100, WG130, and WG131 transmissions used in medium-duty trucks, buses, and off-highway equipment. It also applies to select WG180 and WG200 variants where the same M8 thread pattern is used for bearing cover retention. Always verify thread pitch and length against your specific housing. For complete rebuilds, pair this screw with the 4108306173: GASKET and 0750110040: SHAFT SEAL to prevent leaks. The 4108102042: INPUT and 4108302099: PLANET CARRIER assemblies also rely on this fastener for structural integrity.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4108101112 | HOUSING | Main transmission case section |
| 4108201177 | HOUSING | Rear housing adapter |
| 0636302056 | SCREW PLUG | Oil drain/fill port seal |
| 4108301304 | BEARING COVER | Retains output shaft bearing |
| 4108306173 | GASKET | Seals housing joints |
| 0750110040 | SHAFT SEAL | Prevents oil leakage at shafts |
| 4108102042 | INPUT | Input shaft assembly |
| 4108302099 | PLANET CARRIER | Holds planetary gears |
| 4108302007 | BEARINGSHEET | Thrust bearing shim |
| 0635332196 | BALL BEARING | Radial support for shafts |
