Overview
The ZF 4661.372.024 PISTON is a critical hydraulic actuation component engineered for the WG 90 and WG 94 series transmissions. This OEM genuine part converts hydraulic pressure into mechanical force to engage clutch packs and modulate gear shifts within the transmission valve body. The SKU 4661.372.024 sits directly inside the transmission housing assembly, where it interfaces with the clutch drum and sealing rings to ensure precise oil flow control. Without this piston, the transmission cannot achieve proper line pressure modulation, leading to immediate operational failure.
Symptoms of Failure
- Delayed or harsh gear engagement: When the 4661.372.024 piston wears, hydraulic pressure bleeds past the seals, causing a noticeable lag when shifting from Neutral to Drive or Reverse.
- Intermittent gear slipping under load: A worn piston surface cannot maintain consistent clamping force on the clutch pack, resulting in RPM flare during acceleration.
- Transmission fluid contamination: Cracks or scoring on the piston face allow metal debris to circulate, often visible as dark particles in the oil pan.
- Low line pressure warnings: Diagnostic codes for insufficient main pressure frequently trace back to a leaking 4661.372.024 piston in the valve body circuit.
Technical Specifications
| Part Number | 4661.372.024 |
| Material | Hardened aluminum alloy with anodized surface |
| Outer Diameter | 48.5 mm |
| Inner Diameter | 22.0 mm |
| Height | 32.8 mm |
| Weight | 0.14 kg |
| OEM Reference | ZF 4661.372.024 |
| Seal Groove | Single lip, 2.5 mm width |
Compatibility
This piston is designed for ZF WG series transmissions, specifically the WG 90 and WG 94 models. It also fits the WG 180, WG 200, and WG 250 variants when used in hydraulic clutch actuation circuits. The 4661.372.024 replaces earlier revisions in the WG 92 and WG 96 series. Always verify the piston bore diameter in your TRANSMISSION HOUSING before installation, as the HOUSING II may have different tolerances in later production runs.
During rebuild, this piston works in conjunction with the TUBE that routes oil to the clutch drum, and the CYLINDRICAL PIN that aligns the piston return spring. Proper seating of the piston against the housing bore is essential to prevent cross-leakage between clutch circuits.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4661101020 | TRANSMISSION HOUSING | Main structural casing for gear train and valve body |
| 4661301046 | HOUSING II | Secondary housing for clutch drum support |
| 4661301093 | TUBE | Oil delivery conduit between valve body and clutch |
| 0631306174 | CYLINDRICAL PIN | Alignment pin for piston return spring |
| 0769123894 | TYPE PLATE | Identification plate for transmission model |
| 0750100022 | SCREW PLUG | Sealing plug for pressure test ports |
| 0636302602 | SCREW PLUG | Drain plug for oil pan |
| 0634100633 | O-RING | Seal between piston and housing bore |
| 4661301041 | NOZZLE | Oil jet for clutch cooling |
| 4661301038 | NOZZLE | Secondary oil jet for lubrication |
