Overview
The ZF 0737.835.008 UNION SCREW is a critical hydraulic sealing component engineered for the WG 210 Series transmission. This OEM genuine part functions as a high-pressure fluid connector, securing oil passages within the valve body assembly to maintain precise clutch and gear actuation. Positioned directly between the main control unit and the TRANSMISSION HOUSING, the union screw (SKU: 0737.835.008) prevents cross-contamination of hydraulic circuits while withstanding extreme thermal cycling. Its failure directly compromises shift quality and system pressure integrity.
Symptoms of Failure
- Hydraulic fluid seepage at union screw interface: Visible oil residue around the screw head or mating surface indicates seal degradation, often mistaken for housing gasket leaks.
- Erratic gear engagement under load: Worn threads or micro-cracks cause pressure loss, resulting in delayed shifts or temporary neutral conditions during acceleration.
- Audible whining from transmission sump: Air ingestion through a compromised union screw creates cavitation noise, particularly in cold-start scenarios.
- Intermittent transmission overheating: Reduced hydraulic flow from a leaking union screw forces the torque converter to work harder, elevating operating temperatures by 15-20°F.
Technical Specifications
| Part Number | 0737.835.008 |
| Material | Case-hardened steel (DIN 1.7131) with zinc-nickel plating |
| Thread Size | M18 x 1.5 metric fine pitch |
| Overall Length | 42.5 mm ±0.3 mm |
| Hex Head | 24 mm AF (across flats) |
| Seal Type | Integrated copper crush washer (pre-installed) |
| Weight | 0.085 kg (0.187 lbs) |
| OEM Reference | ZF 0737.835.008 (genuine) |
| Torque Spec | 45 Nm ±5 Nm (dry installation) |
Compatibility
This union screw is validated for the following ZF transmission platforms: WG 210 Series (primary application), WG 200 Series (retrofit compatible with adapter kits), and WG 180 Series (limited to early production units with M18 ports). It interfaces directly with the HOUS.FRONT SECT and HOUSING REAR PART castings. Always verify thread pitch compatibility with your specific housing variant. The CYLINDRICAL PIN must be inspected during replacement to ensure proper alignment of the union screw bore.
Related Components
| Part Number | Name | Function |
|---|---|---|
| 4657101042 | TRANSMISSION HOUSING | Main structural casing containing all rotating assemblies |
| 4657201028 | HOUS.FRONT SECT | Front section housing torque converter and pump |
| 4657201013 | HOUSING REAR PART | Rear casting supporting output shaft and PTO interface |
| 0631306792 | CYLINDRICAL PIN | Alignment dowel for housing-to-housing registration |
| 0636100801 | CAP SCREW | M10 bolt securing valve body to housing |
| 4656301148 | FIXING PLATE | Retainer for oil pump assembly |
| 4657301034 | SCREEN SHEET | Fine mesh filter for main sump suction |
| 4657301035 | SCREEN SHEET | Coarse mesh pre-filter for auxiliary circuit |
| 0636100803 | CAP SCREW | M12 bolt for rear housing attachment |
| 4656301048 | OIL FEED.HOUSG. | Pressurized oil distribution manifold |
Authorized ZF Distributor
We are a certified supplier of genuine ZF components.
