Overview
The ZF 4661.206.001 FILLER PIECE is a precision-engineered spacer component designed for the WG 90 and WG 94 series transmissions. This OEM genuine part sits within the lower valve body assembly, where it functions as a critical alignment and sealing interface between the main TRANSMISSION HOUSING and the internal hydraulic circuit. By maintaining proper clearance and fluid channel integrity, the filler piece ensures consistent oil pressure distribution across the clutch packs. The SKU 4661.206.001 is manufactured to ZF’s exacting tolerances, making it an essential component for any rebuild or repair involving the WG90 or WG94 gearbox.
Symptoms of Failure
- Intermittent gear slipping under load: When the filler piece deforms or wears, hydraulic pressure drops in specific circuits, causing the transmission to slip during acceleration or hill climbs.
- External oil seepage from the valve body joint: A degraded filler piece compromises the seal between the housing and valve body, leading to visible ATF leaks around the transmission pan area.
- Erratic shift timing or harsh engagement: Worn filler pieces alter fluid flow paths, resulting in delayed upshifts or abrupt downshifts that worsen as transmission temperature rises.
- Low line pressure readings during diagnostic testing: Technicians often trace insufficient main pressure to a cracked or compressed filler piece that bypasses fluid away from the pump circuit.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number | 4661.206.001 |
| Material | High-strength aluminum alloy with anodized coating |
| Length | 78.5 mm |
| Width | 34.2 mm |
| Height | 12.8 mm |
| Weight | 0.084 kg |
| OEM Reference | ZF 4661.206.001 |
| Surface Finish | Ground flatness within 0.02 mm |
Compatibility
This filler piece is specifically engineered for the ZF WG90 and WG94 series transmissions. It is a direct-fit component for the following models: WG90, WG94, WG180, WG200, and WG210. The part also applies to select variants of the Ecomat 4HP and 5HP series where the valve body architecture shares the same filler piece cavity. Always verify your transmission’s serial number against the OEM parts catalog before installation. For complete assembly, this filler piece works in conjunction with the HOUSING II and the TUBE, which routes fluid to the upper valve body. The CYLINDRICAL PIN secures the filler piece in its precise location during assembly.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4661101031 | TRANSMISSION HOUSING | Main structural casing for gear train |
| 4661301046 | HOUSING II | Secondary housing for valve body support |
| 4661301093 | TUBE | Fluid passage conduit between housings |
| 0631306174 | CYLINDRICAL PIN | Alignment dowel for filler piece |
| 0769123894 | TYPE PLATE | Identification tag for transmission model |
| 0750100022 | SCREW PLUG | Sealing plug for oil gallery access |
| 0636302602 | SCREW PLUG | Drain plug for valve body cavity |
| 0634100633 | O-RING | Hydraulic seal for plug interfaces |
| 4661301041 | NOZZLE | Oil jet for clutch pack lubrication |
| 4661301038 | NOZZLE | Secondary oil jet for planetary gears |
