ZF 4661.002.004 4 WG 90 Powershift Transmission Assembly | Complete Unit

Overview

The ZF 4661.002.004 4 WG 90 Powershift Transmission Assembly is a complete, factory-matched unit designed for heavy-duty off-highway applications. This assembly integrates the clutch pack, planetary gear sets, and hydraulic control valving into a single, ready-to-install package. As the core rotating assembly within the WG 90 series, it transfers engine torque through four forward and three reverse speeds. The SKU 4661.002.004 denotes a fully assembled unit, eliminating the need for individual component stacking. It sits directly between the torque converter and the output flange, serving as the primary power delivery module.

Symptoms of Failure

• Delayed or harsh engagement: When the unit wears, operators report a noticeable lag when shifting from neutral to forward or reverse, often followed by a jarring engagement. This indicates internal clutch pack wear or hydraulic pressure loss.
• Intermittent gear slipping under load: A common long-tail search query is “powershift transmission slipping in third gear.” The 4661.002.004 assembly can lose holding power in specific ranges, causing the engine to rev without proportional vehicle movement.
• Contaminated hydraulic oil with metallic debris: Worn bearings or clutch plates shed fine metal particles. If you find glitter-like shavings in the oil filter or drain plug, the internal rotating assembly requires immediate replacement.
• External oil seepage at the housing joint: Cracks or warpage in the main casing can cause fluid to weep around the mating surfaces, often mistaken for a simple gasket failure.

Technical Specifications

Compatibility

This complete unit is engineered for the ZF WG 90 series of powershift transmissions. It is a direct fit for the WG 90 and WG 100 models commonly found in telescopic handlers, wheel loaders, and industrial forklifts. While the WG 180 and WG 200 series use a larger planetary carrier, the 4661.002.004 is not interchangeable with those heavier-duty variants. Always verify your transmission model tag before ordering.

During installation, this assembly mates directly to the TRANSMISSION HOUSING and the HOUSING II which encloses the rear clutch pack. The internal lubrication path relies on the TUBE to direct oil flow to the rotating drum. Additionally, the CYLINDRICAL PIN is used to align the assembly during final torque-down, preventing misalignment of the splined shafts.

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