Overview
The ZF 4657.374.026 IDLER is a precision-machined gear component engineered specifically for the WG210 series transmission. This OEM genuine part functions as a critical torque transfer element within the planetary gearset, meshing directly with the sun gear and ring gear to maintain proper rotational synchronization. Positioned on the intermediate shaft, the idler reduces vibration and ensures smooth power distribution under heavy loads. The SKU 4657.374.026 is manufactured to ZF’s exacting tolerances, guaranteeing a direct fit and long service life in industrial drivetrains. When replacing this idler, it is essential to inspect the surrounding TRANSMISSION HOUSING for wear, as housing deformation can accelerate idler failure.
Symptoms of Failure
- Whining or grinding noise from transmission: A worn 4657.374.026 idler produces a distinct high-pitched whine during gear engagement, often mistaken for bearing failure. This noise intensifies under load and indicates pitting on the gear teeth.
- Intermittent gear slipping under torque: As the idler’s tooth profile degrades, the transmission may momentarily lose power transfer, causing a slipping sensation when accelerating or climbing. This symptom is frequently searched as “ZF WG210 slipping under load.”
- Metallic debris in transmission oil: Flaking or chipped idler teeth shed fine metallic particles into the lubricant. Inspecting the oil filter or drain plug for silver glitter is a reliable diagnostic check for idler wear.
- Vibration in neutral or park: A damaged idler can create uneven rotational forces, transmitting vibration through the HOUS.FRONT SECT and into the vehicle chassis, even when the transmission is not engaged.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 4657.374.026 |
| Material | Case-hardened alloy steel (20MnCr5 equivalent) |
| Weight | 1.85 kg (4.08 lbs) |
| Outer Diameter | 98.5 mm |
| Inner Bore Diameter | 35.0 mm |
| Tooth Count | 28 |
| OEM Reference | ZF 4657.374.026 |
| Surface Hardness | 58-62 HRC |
Compatibility
This idler is a direct OEM replacement for the ZF WG210 series transmission. Based on its design and tooth geometry, it is also compatible with the following ZF models: WG180, WG200, WG211, and WG220. The part integrates with the HOUSING REAR PART and is secured using the CYLINDRICAL PIN for precise alignment. Always verify the serial number of your transmission before ordering, as minor revisions exist in early WG180 units.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4657101042 | TRANSMISSION HOUSING | Main structural casing for gear assembly |
| 4657201028 | HOUS.FRONT SECT | Front section housing for input shaft |
| 4657201013 | HOUSING REAR PART | Rear housing supporting output shaft |
| 0631306792 | CYLINDRICAL PIN | Alignment pin for housing sections |
| 0636100801 | CAP SCREW | Fastener for housing assembly |
| 4656301148 | FIXING PLATE | Secures idler shaft in position |
| 4657301034 | SCREEN SHEET | Oil filter screen for debris protection |
| 4657301035 | SCREEN SHEET | Secondary oil filter screen |
| 0636100803 | CAP SCREW | Bolt for screen sheet retention |
| 4656301048 | OIL FEED.HOUSG. | Oil supply channel housing |
