ZF 4108.303.335 SUN GEAR for WG100/WG130/WG131 | OEM Genuine Part

Overview

The ZF 4108.303.335 SUN GEAR is a critical planetary component within the WG100, WG130, and WG131 transmission series. As the central input gear for the planetary gearset, it transfers torque directly from the MOTOR to the planetary pinions, enabling smooth ratio changes under heavy load. This OEM genuine part (SKU: 4108.303.335) is precision-ground to maintain exact tooth geometry, ensuring minimal backlash and maximum power density. The sun gear sits inside the HOUSING and is secured by the COVER, with the ROLLER BEARING supporting its axial and radial loads during operation.

Symptoms of Failure

• Whining or howling noise during acceleration: Worn sun gear teeth create irregular meshing with planetary pinions, producing a distinct high-pitched sound that intensifies under torque.
• Intermittent gear slipping in forward gears: When the sun gear’s splines strip or teeth chip, the planetary set loses its ability to hold ratio, causing sudden RPM flares without corresponding vehicle speed increase.
• Metallic debris in transmission fluid: Flaking or pitting on the sun gear’s contact surfaces sheds fine steel particles into the oil, often visible during drain intervals or on the magnet of the ROLLER BEARING.
• Hard shifting or delayed engagement: Excessive wear on the sun gear’s thrust face alters the planetary carrier’s axial position, interfering with clutch pack timing and causing harsh shifts.

Technical Specifications

Compatibility

This genuine ZF sun gear is engineered for the following transmission models: WG100, WG130, and WG131. It is also compatible with select variants of the WG180 and WG200 series that share the same planetary carrier design. Always verify the spline count and tooth profile against your existing part before installation. The gear interfaces directly with the HOUSING and the COVER assembly, and its proper fitment is essential for the ROLLER BEARING to maintain correct preload.

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