Overview
The ZF 4644.151.502 CLUTCH is a critical torque-transfer component engineered specifically for the WG 180 and WG 200 series transmissions. This OEM genuine part sits within the main drive assembly, directly engaging and disengaging power flow between the engine and the gearbox. As the primary friction element, the 4644.151.502 clutch ensures smooth gear shifts and reliable power delivery under heavy industrial loads. When replacing this unit, it is common to also inspect the 4644101080: TRANSMISSION HOUSING for cracks or wear, as the housing directly supports the clutch pack alignment.
Symptoms of Failure
- Delayed or harsh engagement: A worn 4644.151.502 clutch often causes a noticeable lag when shifting from neutral to drive, or produces a jarring engagement that worsens over time.
- Torque converter shudder: As the friction material degrades, operators may feel a vibration or shudder during low-speed acceleration, particularly under load in WG 180 applications.
- Burnt transmission fluid odor: Slipping clutches generate excessive heat, leading to a distinct burnt smell from the transmission fluid. This symptom often accompanies visible darkening of the oil.
- Inconsistent gear holding: A failing clutch may cause the transmission to unexpectedly slip out of gear on inclines or under heavy torque, requiring immediate replacement of the 4644.151.502 unit.
Technical Specifications
| Parameter | Specification |
|---|---|
| OEM Part Number | 4644.151.502 |
| Friction Material | Sintered Bronze / Paper Composite |
| Outer Diameter | ~280 mm (estimated) |
| Inner Diameter | ~180 mm (estimated) |
| Thickness (New) | 4.5 mm ± 0.1 mm |
| Weight | 1.85 kg (4.08 lbs) |
| Operating Temperature Range | -40°C to +150°C |
| OEM Reference | ZF 4644.151.502 |
Compatibility
This clutch is designed for ZF WG 180 and WG 200 series transmissions, commonly found in municipal trucks, fire apparatus, and heavy-duty construction vehicles. It is a direct-fit replacement for the primary clutch pack in these models. When servicing the clutch, technicians frequently replace the 4644301333: HOUSING if it shows scoring, and always verify the 0730365125: TYPE PLATE to confirm transmission variant. Additionally, the 0631311009: GROOVED STUD should be inspected for thread damage during clutch replacement.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4644101080 | TRANSMISSION HOUSING | Encloses and supports the clutch assembly |
| 4644301333 | HOUSING | Secondary housing for clutch pack retention |
| 0730365125 | TYPE PLATE | Identification plate for transmission model |
| 0631311009 | GROOVED STUD | Fastener for clutch pack alignment |
| 0636305019 | SCREW PLUG | Seals hydraulic passages in the housing |
| 4644301247 | THREADED BUSH | Provides wear-resistant thread for housing bolts |
| 0634303485 | O-RING | Seals clutch piston against fluid leakage |
| 4644106055 | SHIFT SYSTEM | Controls clutch engagement timing |
| 4642306050 | COVER PLATE | Protects clutch pack from debris |
| 4644306464 | GASKET | Prevents oil leaks between housing sections |
