Overview
The ZF 4699.303.121 Sun Gear Shaft is a critical torque-transfer component located within the planetary gear set of WG-series transmissions. This OEM genuine part transmits rotational force from the input shaft to the planetary gears, enabling smooth ratio changes under heavy load. As a hardened steel shaft with precision-ground splines, it directly interfaces with the 4699101136 HOUSING and the 4699301218 HOUSING to maintain concentric alignment. The SKU 4699.303.121 is machined to exact ZF tolerances, ensuring zero-play engagement with mating gears in the WG100, WG130, and WG131 assemblies.
Symptoms of Failure
- Erratic gear engagement or slipping under load: Worn splines on the sun gear shaft cause intermittent power loss, especially during uphill climbs or heavy hauling.
- Metallic grinding noise from the transmission bell housing: Pitting or spalling on the shaft surface creates a distinct whine or grinding sound that intensifies with RPM.
- Oil contamination with metallic debris: Flaking material from a fatigued shaft circulates through the hydraulic system, often visible as glitter in the fluid during drain intervals.
- Hard shifting or delayed clutch pack engagement: A bent or cracked sun gear shaft disrupts planetary gear timing, causing harsh shifts or hesitation between gears.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number (SKU) | 4699.303.121 |
| Overall Length | 185 mm (estimated) |
| Outer Diameter (spline) | 32 mm (estimated) |
| Inner Bore Diameter | 18 mm (estimated) |
| Material | Case-hardened alloy steel (20MnCr5 equivalent) |
| Weight | 0.85 kg (estimated) |
| OEM Reference | ZF 4699.303.121 |
| Surface Hardness | 58-62 HRC |
Compatibility
This sun gear shaft is designed exclusively for ZF WG-series transmissions. Confirmed compatible models include the WG100, WG130, and WG131. It may also fit the WG180 and WG200 variants when used in conjunction with the 4699309114 HOUSING COVER and proper 0636101411 CAP SCREW torque specifications. Always verify spline count and shaft length against your transmission’s serial number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4699101136 | HOUSING | Encloses the sun gear shaft and planetary carrier |
| 4699301218 | HOUSING | Rear housing supporting output shaft alignment |
| 4699309114 | HOUSING COVER | Seals the gear train and retains lubrication |
| 0636101411 | CAP SCREW | Secures housing covers to transmission case |
| 0631302072 | CYLINDRICAL PIN | Aligns housing halves during assembly |
| 0636302013 | SCREW PLUG | Closes oil passages in the housing |
| 0501331653 | SCREW PLUG | Seals pressure test ports |
| 0634801038 | SEALING RING | Prevents fluid leaks at shaft interfaces |
| 0637885613 | BREATHER | Equalizes internal pressure and vents moisture |
| 0769100082 | TYPE PLATE | Identifies transmission model and serial number |
ZF 4699.303.121 SUN GEAR SHAFT – Shaft RFQ Support
For ZF 4699.303.121 SUN GEAR SHAFT, send the part number, removed-part photos, and application context so PartsZF can prepare a focused sourcing response.
Part-Number Summary
Use ZF number 4699.303.121 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 | 4699.303.121 |
|---|---|
| Normalized SKU | 4699303121 |
| Part name | SUN GEAR SHAFT |
| Product category | shaft |
| 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.
Related Parts
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- ZF 2094.110.014 P.T.O. SHAFT
- ZF 4642.303.002 OUTPUT SHAFT
- ZF 2093.110.011 P.T.O. SHAFT
- ZF 5838.300.106 INPUT SHAFT
