ZF 4699.803.039 GK20 | OEM Genuine Part

Overview

The ZF 4699.803.039 GK20 is a critical OEM genuine component engineered for the internal hydraulic and mechanical control systems within ZF construction machinery transmissions. This part functions as a precision-machined spool or valve element, directing oil flow for clutch engagement and gear selection. It sits within the main valve body or control housing assembly, directly influencing shift quality and pressure regulation. The SKU 4699.803.039 is specifically designed to meet ZF’s exacting tolerances, ensuring reliable operation under high-load conditions typical of wheel loaders, graders, and heavy-duty trucks.

Symptoms of Failure

When the ZF 4699.803.039 GK20 begins to wear, operators often notice delayed or harsh gear engagement during directional shifts. A second common symptom is intermittent transmission slipping under load, particularly when climbing or pushing heavy material. You may also observe erratic pressure fluctuations on diagnostic gauges, leading to inconsistent clutch pack application. Finally, internal contamination from metallic debris can accelerate wear, causing the part to stick and resulting in a loss of drive in specific ranges.

Technical Specifications

Compatibility

This GK20 component is primarily compatible with ZF’s WG series powershift transmissions, including the WG180, WG200, and WG250 models. It is also used in certain ZF 4WG-200 and ZF 6WG-250 variants found in construction machinery. Always verify your transmission serial number before ordering, as minor revisions may require specific valve body configurations.

During installation, the 4699101045 HOUSING provides the primary bore for this spool, while the 4699301108 HOUSING supports adjacent control circuits. The 4699301085 COVER seals the valve body, and the 4699301014 THREAD PROTECTIVE SHIELD safeguards threaded ports from debris during service.

Related Components