ZF 0636.101.665 CAP SCREW for WG90/WG94 | OEM Genuine Part

Overview

The ZF 0636.101.665 CAP SCREW is a critical fastening component engineered specifically for the WG90 and WG94 transmission series. This OEM genuine part secures internal hydraulic passages and housing interfaces within the gearbox, preventing pressurized oil from bypassing critical circuits. Located within the main valve body or clutch housing assembly, the cap screw (SKU: 0636.101.665) ensures that mating surfaces remain tightly sealed under high torque and thermal cycling. When installed correctly, it maintains the structural integrity of the 4661101001: TRANSMISSION HOUSING and the 4661301007: HOUSING, both of which rely on this fastener to prevent fluid migration between chambers.

Symptoms of Failure

• External oil seepage around the bolt head: A worn or stripped cap screw allows transmission fluid to weep past the sealing face, often leaving visible residue on the housing exterior.
• Erratic shift engagement or clutch slip: When this fastener loosens, internal line pressure drops, causing delayed or harsh gear changes during acceleration.
• Metallic debris in the oil pan: A fractured cap screw can shed particles into the lubrication circuit, leading to bearing or bushing damage over time.
• Audible ticking or knocking from the transmission: Loose fasteners create vibration between the 4661301093: TUBE and the housing, producing a distinct mechanical noise under load.

Technical Specifications

Compatibility

This cap screw is a direct fit for ZF WG90 and WG94 series transmissions, which are commonly found in medium-duty trucks, buses, and off-highway equipment. Based on its thread pattern and application, it also serves as a replacement fastener in the WG180, WG200, and WG250 series where similar housing interfaces exist. The 0631306174: CYLINDRICAL PIN is frequently replaced concurrently, as both components work together to align and secure the valve body assembly.

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