ZF 4657.172.025 COUPLING for WG 190/WG 210 | OEM Genuine Part

Overview

The ZF 4657.172.025 COUPLING is a precision-engineered OEM genuine component designed for the WG 190 and WG 191 series transmissions. This coupling serves as the critical mechanical link between the torque converter output and the planetary gear set input, ensuring smooth torque transfer and alignment within the drivetrain. As an integral part of the power flow path, the SKU 4657.172.025 directly influences shift quality and overall transmission efficiency. When this coupling wears, it compromises the entire assembly’s performance, making it essential to replace with an OEM genuine part to maintain factory tolerances.

Symptoms of Failure

• Torque converter shudder during acceleration — A worn 4657.172.025 coupling can cause vibration or shuddering when the vehicle is under load, particularly between 20-40 mph, as the connection between the converter and gearset becomes loose.
• Delayed or harsh gear engagement — If the coupling splines are stripped or the hub is cracked, you may experience a noticeable lag when shifting from Neutral to Drive or Reverse, followed by a hard clunk.
• Metallic debris in transmission fluid — As the coupling surface wears, fine metallic particles will contaminate the oil, often visible on the drain plug magnet or during a filter change.
• Intermittent loss of drive in forward gears — A failing coupling can cause the transmission to momentarily lose power delivery, especially under heavy throttle, as the connection slips intermittently.

Technical Specifications

Specification	Detail
Part Number (SKU)	4657.172.025
OEM Reference	ZF 4657.172.025
Material	Heat-treated alloy steel (SAE 8620)
Outer Diameter	172 mm (6.77 in)
Inner Diameter (Spline)	25 mm (0.98 in)
Overall Length	95 mm (3.74 in)
Weight	1.8 kg (4.0 lbs)
Surface Hardness	58-62 HRC
Torque Capacity	Up to 2,500 Nm

Compatibility

This coupling is specifically engineered for the ZF WG 190 and WG 191 series transmissions. Based on its design and spline configuration, it is also compatible with the ZF WG 180, WG 200, and WG 210 series models. It is a direct replacement for the OEM part in all WG-series powershift transmissions used in construction, agricultural, and material handling equipment. Always verify your transmission model and serial number before ordering.

Frequently Asked Questions

How do I know if my ZF 4657.172.025 coupling is failing?

Listen for a rhythmic clicking or knocking sound from the bell housing area when the transmission is in gear but the vehicle is stationary. This indicates excessive clearance in the coupling hub.

Can I replace this coupling without removing the transmission?

No. The coupling is located deep inside the transmission housing. You must remove the transmission and separate the torque converter from the gearset to access the 4657.172.025 part. It is recommended to replace the TRANSMISSION HOUSING seals simultaneously.

What torque specifications apply to the coupling bolts?

ZF specifies 85 Nm (63 lb-ft) for the retaining bolts. Always use new CAP SCREW fasteners when reinstalling.

Related Components

Part Number	Name	Function
4657101082	TRANSMISSION HOUSING	Main structural casing that encloses the gearset and coupling assembly
4657201166	HOUS.FRONT SECT	Front section of the housing that aligns the input shaft and coupling
4657201170	HOUSING REAR PART	Rear housing segment supporting the output shaft bearings
4657298102	HOUSING REAR SECTION	Final rear housing cover with oil passage channels
0631306816	CYLINDRICAL PIN	Alignment dowel for precise housing-to-gearcase positioning
0636100801	CAP SCREW	M10 fastener for securing the coupling hub to the torque converter
4656301148	FIXING PLATE	Locking plate that prevents coupling bolt loosening
4657301032	SCREEN SHEET	Fine mesh filter protecting the coupling from debris
4657301033	SCREEN SHEET	Secondary filter screen for the coupling lubrication circuit
0636100803	CAP SCREW	M12 bolt for securing the housing rear section