ZF 4108.303.326 SUN GEAR for WG100/WG130/WG131 | OEM Genuine Part

Overview

The ZF 4108.303.326 SUN GEAR is a critical planetary component engineered for the WG100, WG130, and WG131 transmission series. As the central input gear within the planetary gearset, it distributes torque from the MOTOR to the planet gears, enabling smooth ratio changes under heavy loads. This OEM genuine part (SKU: 4108.303.326) is precision-machined to maintain exact mesh alignment with the planetary carrier and ring gear, ensuring minimal backlash and maximum power transfer efficiency in your ZF drivetrain.

Symptoms of Failure

• Whining or howling noise during acceleration: Worn sun gear teeth create irregular contact patterns, producing a distinct high-pitched sound that intensifies under load.
• Intermittent gear slipping in forward or reverse: As the sun gear’s splines wear, torque transfer becomes inconsistent, causing the transmission to momentarily lose drive engagement.
• Metallic debris in transmission fluid: Flaking or pitting on the sun gear’s tooth flanks sheds fine metal particles, which can be detected during routine oil changes or filter inspections.
• Hard shifting or delayed engagement: Excessive wear alters the gearset’s preload, forcing the COVER and valve body to compensate with higher hydraulic pressure.

Technical Specifications

Compatibility

This sun gear is a direct fit for ZF WG100, WG130, and WG131 transmissions. It also serves as a service replacement for certain variants of the WG180 and WG200 series when used in conjunction with the correct HOUSING and TAPERED ROLLER BEARING. Always verify your transmission’s serial number against the OEM parts catalog to confirm interchangeability.

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