ZF 4651.004.020 4 WG 100(500) Powershift Transmission Assembly | Complete Unit

Overview

The ZF 4651.004.020 4 WG 100(500) Powershift Transmission Assembly represents a complete, fully assembled unit engineered for demanding industrial drivetrains. As the core hydraulic-mechanical module, this assembly integrates the clutch packs, valve body, and planetary gear sets into a single ready-to-install package. The SKU 4651.004.020 is a direct replacement for the original WG 100 series assembly, ensuring precise alignment within the transmission housing. This unit is designed to manage high torque loads in construction, agricultural, and material handling equipment, providing smooth power shifts under load. When paired with a properly sealed TRANSMISSION HOUSING, this assembly delivers reliable performance in the most abrasive environments.

Symptoms of Failure

• Delayed or harsh gear engagement: Worn internal clutch discs or piston seals cause hesitation when shifting from neutral to forward or reverse, often accompanied by a jarring engagement. This is a common search query for “ZF WG 100 shifting delay.”
• Transmission fluid contamination with metallic debris: As internal bearings or gear teeth degrade, fine metal particles appear in the oil filter or sump, indicating imminent failure of the complete unit.
• Loss of power under load (slipping): The transmission may rev higher than expected without proportional vehicle movement, particularly when climbing grades or carrying heavy loads. This “ZF powershift slipping” symptom often requires immediate replacement.
• External oil leaks near the bell housing: Cracks in the assembly housing or degraded O-rings allow hydraulic fluid to escape, leading to low pressure and eventual system shutdown. Check the O-RING seals during installation.

Technical Specifications

Compatibility

This complete unit is specifically designed for the ZF WG 100 series transmissions, including models such as the WG 100(500) and WG 100(600). It is also compatible with select variants of the WG 120 and WG 150 series where the mounting flange and input shaft dimensions match. For applications in the WG 180 or WG 200 series, verify the bell housing pattern and torque converter pilot diameter. The assembly integrates directly with the HOUSING (part 4651301029) and the HOUSING (part 4651301024) to form the complete transmission case. Always cross-reference your existing unit’s serial number before ordering.

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