Overview
The ZF 6006.020.003 FS SG 4 is a critical synchronizer assembly designed for the WG180 and WG200 series transmissions. This OEM genuine part governs the smooth engagement of gear ratios within the countershaft system, ensuring precise power transfer from the engine to the driveline. The SKU 6006.020.003 is specifically engineered to interface with the TRANSMISSION HOUSING and the OUTPUT FLANGE, forming the core of the gear selection mechanism. Without this component, the transmission cannot maintain consistent torque delivery under load.
Symptoms of Failure
- Grinding or clashing noises during gear engagement: A worn 6006.020.003 synchronizer fails to match shaft speeds, causing audible metal-on-metal contact when shifting.
- Hard shifting or gear lockout: Operators may experience resistance when moving the shift lever, particularly in lower gears, as the synchronizer hub loses its friction capacity.
- Transmission oil contamination with metallic debris: As the synchronizer rings degrade, fine metal particles circulate through the system, often detected during routine oil changes.
- Unintended gear disengagement under load: A failing FS SG 4 unit cannot hold the selected gear, leading to sudden neutral conditions during acceleration.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 6006.020.003 |
| Designation | FS SG 4 Synchronizer Assembly |
| Material | Hardened steel hub with brass synchronizer rings |
| Weight | 2.8 kg (6.2 lbs) |
| Outer Diameter | 180 mm |
| Inner Diameter | 65 mm |
| OEM Reference | ZF 6006.020.003 |
| Compatible Fasteners | HEXAGON SCREW M10 x 30 mm |
Compatibility
This synchronizer is engineered exclusively for ZF WG180 and WG200 series transmissions. It is a direct replacement for units requiring the FS SG 4 configuration, commonly found in WG180-4, WG180-6, WG200-4, and WG200-6 models. The part integrates with the DISCONNECTION mechanism to facilitate clutch-free shifting. Always verify the transmission serial number against the ZF parts catalog before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644105475 | DISCONNECTION | Engages/disengages the synchronizer from the gear train |
| 4642303097 | OUTPUT FLANGE | Transfers torque from the synchronizer to the driveshaft |
| 0636020211 | HEXAGON SCREW | Secures the synchronizer hub to the shaft |
| 4644101134 | TRANSMISSION HOUSING | Encloses the synchronizer assembly |
| 4644301349 | HOUSING | Supports the synchronizer fork mechanism |
| 0730365125 | TYPE PLATE | Identifies transmission model and part specifications |
| 0631311009 | GROOVED STUD | Positions the synchronizer ring within the hub |
| 0636305019 | SCREW PLUG | Seals the synchronizer access port |
| 4644301247 | THREADED BUSH | Provides wear surface for the shift fork |
| 0634303485 | O-RING | Prevents oil leakage around the synchronizer shaft |
