ZF 4108.303.325 SUN GEAR for WG100/WG130/WG131 | OEM Genuine Part

Overview

The ZF 4108.303.325 SUN GEAR is a critical planetary component engineered for the WG100, WG130, and WG131 transmission series. Positioned at the heart of the planetary gear set, this OEM genuine part transfers torque from the input shaft to the planetary pinions, enabling smooth ratio changes under heavy load. The SKU 4108.303.325 interfaces directly with the HOUSING and the TAPERED ROLLER BEARING to maintain precise gear alignment. As a genuine ZF component, it ensures factory-specified backlash and load distribution, preventing premature wear in the planetary assembly.

Symptoms of Failure

• Whining or howling noise during acceleration — A worn sun gear creates uneven tooth contact, producing a distinct high-pitched whine that intensifies under load. This is a common long-tail search query for “ZF transmission whining noise when accelerating.”
• Intermittent gear slipping or loss of drive — As the sun gear teeth wear, the planetary pinions lose engagement, causing the transmission to slip out of gear unexpectedly, especially during uphill climbs.
• Metallic debris in transmission fluid — Flaking or pitting on the sun gear surface sheds fine metal particles into the oil, visible during fluid changes or on the magnetic drain plug.
• Hard shifting or delayed engagement — Worn sun gear splines cause binding in the planetary carrier, leading to harsh shifts between forward and reverse.

Technical Specifications

Compatibility

This sun gear is specifically designed for ZF WG-series transmissions. Verified compatible models include:

• ZF WG100
• ZF WG130
• ZF WG131
• ZF WG180 (with adapter kit)
• ZF WG200 (limited compatibility, verify spline count)

Always confirm your transmission serial number before ordering. The MOTOR and COVER assemblies in these models share the same planetary carrier interface.

Related Components