Overview
The ZF 1203.306.017 COMPRESSION SPRING is a critical OEM genuine component engineered for the WG 65 Series transmission. This precision spring is responsible for maintaining consistent pressure within the valve body or clutch pack assembly, ensuring smooth gear engagement and hydraulic control. As a factory-specified part, the SKU 1203.306.017 guarantees exact fitment and durability under high-cycle industrial loads. When installed alongside the 4616101059: TRANSMISSION HOUSING, this spring supports the structural integrity of the shift mechanism, preventing unwanted movement or pressure loss during operation.
Symptoms of Failure
When the ZF 1203.306.017 compression spring fatigues or breaks, operators will notice distinct performance issues. Look for these specific failure symptoms to diagnose the problem early:
- Delayed or harsh gear engagement: A worn spring cannot maintain proper preload, causing sluggish shifts or abrupt clunking when moving from neutral to drive.
- Intermittent pressure loss in the hydraulic circuit: You may experience “transmission slipping under load” as the spring fails to hold the valve in position, leading to inconsistent oil flow.
- Unusual metallic rattling from the transmission housing: A broken spring can create loose debris inside the assembly, producing a distinct noise during idle or low-speed operation.
- Erratic shift patterns during temperature changes: As the spring loses its temper, hot oil may cause it to collapse, resulting in “transmission hunting for gears” on inclines.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number (SKU) | 1203.306.017 |
| Material | Chrome Silicon Alloy Steel (DIN 17223) |
| Wire Diameter | 3.5 mm |
| Outer Diameter | 22.0 mm |
| Free Length | 45.0 mm |
| Total Coils | 8.5 |
| Weight | 0.045 kg |
| OEM Reference | ZF 1203.306.017 |
| Surface Treatment | Phosphate coated for corrosion resistance |
Compatibility
This compression spring is primarily designed for the ZF WG 65 Series, but it also fits select heavy-duty transmissions that share the same valve body architecture. Compatible models include the WG180, WG200, WG250, and WG300 series. Always verify the spring’s free length and coil count against your existing part before installation. For secure mounting, use the 0636011038: HEXAGON SCREW and 0636011118: HEXAGON SCREW to fasten the valve body cover, and the 0636016015: HEXAGON SCREW for the housing flange. These fasteners ensure the spring remains properly seated under high vibration.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4616101059 | TRANSMISSION HOUSING | Encloses and supports all internal transmission components |
| 0636011038 | HEXAGON SCREW | Secures valve body and spring retainers |
| 0636011118 | HEXAGON SCREW | Fastens clutch pack housing |
| 0636016015 | HEXAGON SCREW | Mounts transmission flange to engine bell housing |
| 0631306085 | CYLINDRICAL PIN | Aligns valve body and spring guide during assembly |
| 0634313118 | O-RING | Seals hydraulic passages around the spring cavity |
| 0636304019 | SCREW PLUG | Closes pressure test ports on the transmission housing |
| 0634801152 | SEALING RING | Prevents oil leaks at the screw plug interface |
| 0732611049 | FILTER INSERT | Traps debris from spring wear particles in the oil circuit |
| 0634303718 | O-RING | Provides secondary sealing for the valve body cover |
Authorized ZF Distributor
We are a certified supplier of genuine ZF components.
