Overview
The ZF 5838.300.796 PISTON is a critical hydraulic actuation component engineered for the WG100, WG130, and WG131 transmission series. This OEM genuine part converts hydraulic pressure into mechanical force to engage clutch packs and shift gears within the planetary gearset. Positioned inside the transmission valve body and clutch drum assembly, the piston creates a sealed chamber that, when pressurized, moves to clamp friction discs. The SKU 5838.300.796 is precision-machined to exact ZF tolerances, ensuring consistent oil flow and reliable shift timing. When paired with a properly functioning 2093109006: DIFFERENTIAL, this piston maintains the hydraulic integrity necessary for smooth power delivery under heavy loads.
Symptoms of Failure
- Delayed or harsh gear engagement: A worn piston seal causes internal pressure loss, leading to sluggish shifts or sudden clunking when the transmission finally engages.
- Transmission fluid leaks around the bell housing: Cracks or scoring on the piston body allow ATF to bypass the seal, resulting in visible drips and low fluid levels.
- Slipping in forward or reverse gears: Inadequate clamping force from a failing piston allows clutch packs to slip under torque, causing RPM flare without corresponding vehicle speed.
- Erratic shift patterns under load: As the piston loses its ability to hold pressure consistently, the transmission may hunt between gears or fail to hold a gear on inclines.
Technical Specifications
| Specification | Detail |
|---|---|
| Part Number | 5838.300.796 |
| Material | Hard-anodized aluminum alloy with nitrile seal |
| Outer Diameter | 98.5 mm |
| Inner Diameter | 72.0 mm |
| Height | 34.2 mm |
| Weight | 0.28 kg |
| OEM Reference | ZF 5838.300.796 |
| Operating Pressure | 8–12 bar |
Compatibility
This piston is designed for ZF WG-series powershift transmissions used in off-highway and industrial applications. Primary compatibility includes the WG100, WG130, and WG131 models. It may also be retrofitted into certain WG180 and WG200 variants where the clutch drum dimensions match, though verification of the 0750117075: TAPER ROLLER BEARING clearance is recommended. The piston interfaces directly with the 2093209095: DIFFERENTIAL assembly and the 2093309071: DIFF.HOUSING to complete the hydraulic circuit. Always cross-reference your transmission serial number before installation.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 2093109006 | DIFFERENTIAL | Distributes torque between axles |
| 0750117075 | TAPER ROLLER BEARING | Supports rotating shafts under axial load |
| 2093209095 | DIFFERENTIAL | Secondary torque distribution unit |
| 2093309071 | DIFF.HOUSING | Encloses differential gears |
| 0631100223 | SPRING PIN | Retains piston return spring |
| 0730300820 | THRUST WASHER | Reduces axial friction |
| 4482360002 | AXLE BEVEL GEAR | Transfers power to axle shafts |
| 2097309085 | DIFFERENTIAL AXLE | Connects differential to wheel hub |
| 5838300811 | THRUST WASHER | Prevents gear end-play |
| 4482360001 | DIFFERENTIAL BEVEL GEAR | Mesh with axle bevel gear |
Frequently Asked Questions
Q: How do I know if the 5838.300.796 piston is the cause of my transmission slipping?
A: Perform a pressure test at the clutch port. If the reading drops below 8 bar during engagement while the pump is healthy, the piston seal is likely compromised. Visual inspection for scoring on the piston bore is also recommended.
Q: Can this piston be reused if the seal appears intact?
A: ZF recommends replacing the piston as an assembly whenever the transmission is overhauled. Even minor wear on the anodized surface can accelerate seal failure, leading to repeat labor costs.
Q: Is the 5838.300.796 compatible with the WG180 transmission?
A: While the piston diameter matches some WG180 clutch drums, the stroke length differs. Always compare the part number stamped on your existing piston. If it reads 5838.300.796, it is a direct fit.
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Phone: +86 158 2286 3467 |
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