ZF 5840.301.823 SPUR GEAR for WG100/WG130/WG131 | OEM Genuine Part

Overview

The ZF 5840.301.823 SPUR GEAR is a precision-machined component engineered for the auxiliary drive train of ZF WG100, WG130, and WG131 transmissions. This OEM genuine part transmits rotational force between parallel shafts within the gear cluster, directly influencing torque distribution and driveline synchronization. As a critical element in the power flow path, the 5840.301.823 spur gear meshes with adjacent reduction gears to maintain consistent output speed under varying loads. Its location within the transmission housing makes it integral to the overall durability of the gearbox assembly.

Symptoms of Failure

• Whining or howling noise during deceleration: Worn gear teeth create irregular contact patterns, producing a distinct metallic whine that intensifies as the vehicle slows down.
• Intermittent gear slipping under load: When the spur gear’s tooth profile degrades, the transmission may momentarily lose engagement, causing a sudden RPM spike without corresponding acceleration.
• Metallic debris in transmission fluid: Flaking or pitting on the gear surface contaminates the oil, often visible as silver or bronze particles during routine fluid changes.
• Vibration through the shift lever: Excessive backlash from a worn 5840.301.823 spur gear transmits harmonic vibrations into the chassis, particularly noticeable in the 3rd and 4th gear range.

Technical Specifications

Compatibility

This spur gear is specifically designed for ZF WG100, WG130, and WG131 series transmissions. It also fits select variants of the WG180 and WG200 models where the auxiliary drive configuration matches the 23-tooth pattern. Always verify the tooth count and bore diameter against your existing gear before installation. The 5840.301.823 is not compatible with WG150 or WG250 series units without modification to the countershaft assembly.

During replacement, it is common practice to inspect the DIFFERENTIAL HOUSING (2098309010) for cracks or wear, as housing distortion accelerates gear wear. The DIFFERENTIAL (2099109018) and CROWN WHEEL (2099364014) should be checked for matching backlash when the spur gear is replaced. Additionally, the DIFFERENTIAL (2099209001) assembly often requires re-shimming after gear replacement to maintain proper tooth contact patterns.

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