ZF 0636.020.238 HEXAGON SCREW for WG200 | OEM Genuine Part

Overview

The ZF 0636.020.238 HEXAGON SCREW is a critical fastening component engineered specifically for the WG200 series transmission. This OEM genuine part secures the valve body and control housing assembly, ensuring precise hydraulic pressure distribution throughout the gearbox. As a high-tensile fastener, it withstands extreme vibrational loads and thermal cycling common in heavy-duty commercial applications. The SKU 0636.020.238 is manufactured to ZF’s exacting tolerances, guaranteeing a perfect fit within the WG200’s intricate clutch and planetary gear system. When paired with the 4460165051: CONSOLE and the 4460368311: CONSOLE, this hexagon screw forms the structural backbone of the transmission’s upper assembly.

Symptoms of Failure

• Hydraulic fluid seepage around the valve body cover: A loosened or fatigued 0636.020.238 screw allows pressurized ATF to escape, leaving visible oil streaks on the transmission housing. This often manifests as “ZF WG200 oil leak near shift solenoid” in diagnostic reports.
• Erratic gear engagement under load: When this hexagon screw loses clamping force, the valve body shifts minutely, causing delayed or harsh shifts—commonly searched as “WG200 transmission slipping in 3rd gear.”
• Audible rattling from the transmission pan area: A stripped or broken 0636.020.238 permits internal components to vibrate against the housing, producing a metallic chatter during idle. Technicians often query “ZF transmission rattle when accelerating.”
• Intermittent loss of reverse gear: Insufficient torque on this fastener disrupts oil gallery alignment, leading to pressure drops that affect reverse clutch packs—a symptom frequently described as “WG200 no reverse after fluid change.”

Technical Specifications

Compatibility

This hexagon screw is primarily designed for the ZF WG200 series transmissions, including the WG180, WG200, and WG210 variants used in municipal buses, fire trucks, and off-highway equipment. It also fits select ZF Ecomat 4HP and 5HP models where the valve body mounting pattern matches. For proper installation, always use the 0636011429: HEXAGON SCREW for adjacent fasteners and the 0730100365: WASHER to distribute load evenly. Verify compatibility with your transmission’s serial number before ordering.

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