Overview
The ZF 4108.303.309 SUN GEAR is a critical planetary component engineered for the WG100, WG130, and WG131 transmission series. This OEM genuine part functions as the central input gear within the planetary gearset, transferring torque from the MOTOR to the planetary pinions. Precision-ground teeth ensure smooth power distribution and minimal backlash. The SKU 4108.303.309 is manufactured to ZF’s exacting tolerances, making it a direct replacement for worn or damaged sun gears in heavy-duty industrial applications.
Symptoms of Failure
- Transmission gear slipping under load: A worn sun gear loses tooth engagement, causing intermittent power loss during acceleration or uphill operation.
- Metallic grinding noise from the planetary assembly: Pitting or spalling on the sun gear teeth produces a distinct whining or grinding sound, especially in lower gears.
- Increased operating temperature: Excessive friction from a damaged sun gear generates heat, often triggering transmission overheat warnings.
- Metal particles in the oil filter or drain plug: Flaking material from the sun gear contaminates the hydraulic fluid, accelerating wear on the COVER and BUSH components.
Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | 4108.303.309 |
| Material | Case-hardened alloy steel (20MnCr5 equivalent) |
| Outside Diameter | 98.5 mm |
| Inner Bore Diameter | 42.0 mm |
| Tooth Count | 24 teeth (helical) |
| Face Width | 38.2 mm |
| Weight | 1.45 kg |
| OEM Reference | ZF 4108.303.309 |
Compatibility
This sun gear is specifically designed for ZF WG-series transmissions. Verified compatible models include WG100, WG130, and WG131. It may also be suitable for certain WG180 and WG200 variants when used with the correct HOUSING and planetary carrier assembly. Always cross-reference your transmission serial number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4108101140 | HOUSING | Encloses the planetary gearset and supports the sun gear shaft |
| 0501211694 | MOTOR | Provides hydraulic drive input to the sun gear |
| 0501314793 | COVER | Seals the planetary assembly and retains lubrication |
| 0501314799 | BUSH | Supports the sun gear shaft within the housing |
| 0735370299 | TAPERED ROLLER BEARING | Handles axial and radial loads on the sun gear |
| 0501317874 | HOUSING | Secondary housing for planetary carrier support |
| 0501317875 | ROLLER | Reduces friction between planetary gears and carrier |
| 0501209497 | PISTON | Applies clamping force to the clutch pack |
| 0501317876 | COMPRESSION SPRING | Returns the piston to neutral position |
| 0501314823 | BUSH | Guides the sun gear shaft through the carrier |
ZF 4108.303.309 SUN GEAR – Gear RFQ Support
ZF 4108.303.309 SUN GEAR is handled as a gear-train sourcing item for transmission repair teams. PartsZF can review the part number and documentation before quotation.
Part-Number Summary
Use ZF number 4108.303.309 when sending your RFQ. PartsZF can review dotted, spaced, and compact number formats against the available product and documentation records.
Application Context
- Illustration section: OUTPUT
Cross Reference Support
If you have an OEM number, old supplier number, or visible marking, include it with your RFQ so PartsZF can compare it with the available records.
Specification Snapshot
| ZF part number | 4108.303.309 |
|---|---|
| Normalized SKU | 4108303309 |
| Part name | SUN GEAR |
| Product category | gear |
| RFQ support | Part-number lookup and documentation review |
| Media support | Product photo or diagram review when available |
Image and Documentation Notes
Current product media status: fallback. Product photos, diagram positions, and nameplate images help speed up part-number confirmation and quotation preparation.
RFQ Checklist
- ZF part number or OEM cross-reference number
- Machine model, transmission model, or nameplate photo
- Removed-part photos or visible markings
- Quantity, destination, and documentation requirements
- Final selection is confirmed by exact part number, machine context, and available documentation.
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- ZF 4143.142.022 GEAR SHIFT SENSOR
