ZF 4661.002.012 4 WG 90 Powershift Transmission Assembly | Complete Unit

Overview

The ZF 4661.002.012 4 WG 90 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the full gear train, clutch packs, and hydraulic control components into a single ready-to-install package. As the core of the WG 90 series, this SKU 4661.002.012 replaces the entire rotating assembly, ensuring precise gear engagement under load. It sits directly between the TRANSMISSION HOUSING and the HOUSING II, with the TUBE routing lubrication oil to critical bearings. The assembly is secured in place using a CYLINDRICAL PIN for precise alignment.

Symptoms of Failure

• Delayed engagement or gear slippage under load: When the internal clutch discs or seals wear, the transmission hesitates before engaging forward or reverse, or slips during heavy pulling.
• Erratic shifting and harsh engagement: Worn valve body components within the assembly cause abrupt, jarring shifts instead of smooth power transitions.
• Contaminated oil with metallic debris: Internal bearing or gear wear generates metal particles in the transmission fluid, visible during oil changes or as a gritty texture on the dipstick.
• Loss of hydraulic pressure and overheating: A failing pump or leaking seals inside the assembly reduce system pressure, leading to elevated operating temperatures and eventual transmission shutdown.

Technical Specifications

Compatibility

This complete unit is specifically engineered for the ZF WG 90 series powershift transmissions. It is a direct fit for the following models: WG 90, WG 92, WG 94, and WG 96. The assembly is also compatible with select WG 180 and WG 200 variants that share the same 4-speed planetary gearset architecture, though verification of the bell housing pattern is recommended. It is not compatible with the WG 120 or WG 150 series without adapter plates.

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