InMotion WS5778 Differential Pinion Seal - Front Outer or Rear Outer

Differential Pinion Seal for Spicer Axles

The InMotion WS5778 differential pinion seal is built for axle applications that need a precise sealing surface and dependable contaminant protection. Made with fluoro-elastomer and nitrile sealing material, it helps keep gear oil contained while blocking moisture and debris from entering the differential pinion area.

Compatible With a wide range of Ford, Jeep, Dodge, Chevrolet, GMC, Honda, and Isuzu applications, this seal is a direct-fit solution for many front outer and rear outer axle positions. The WS5778 is sized at 1.552 x 3.160 x 0.645 and is engineered for consistent sealing performance in demanding driveline service.

Key Features

• Part number: WS5778
• Fluoro-elastomer construction for sealing durability
• Nitrile sealing material for reliable fluid control
• Inside diameter: 1.54 in. / 39.1 mm
• Outside diameter: 3.17 in. / 80.42 mm
• Thickness: 0.65 in. / 16.4 mm
• Shaft diameter: 1.552 in. / 39.4 mm
• Housing bore: 3.165 in. / 80.3 mm
• Fits front outer and rear outer differential pinion applications

Detailed Description

InMotion WS5778 is a differential pinion seal designed to maintain a tight barrier at the pinion area, where contamination and lubricant loss can quickly affect axle performance. Its precision dimensions and quality sealing materials support a secure fit in supported Spicer axle applications, including many classic and late-model trucks and SUVs. This part cross-references National Oil Seals (e.g., 5778, 7105778) for the same application.

Fits 1994-2003 Dodge Ram 1500, front outer with Spicer 44-3F axle; Fits 1994-2002 Dodge Ram 2500, front outer with Spicer 44-3F axle; Fits 2001 Jeep TJ, rear outer with Spicer 44-1HD axle; Fits 2001 Jeep Wrangler, rear outer with Spicer 44-1HD axle; Fits 1985-2000 Jeep Cherokee, front outer with Spicer 30-AF axle; Fits 1997-2000 Jeep TJ, front outer with Spicer 30-AF axle; Fits 1997-2000 Jeep Wrangler, front outer with Spicer 30-AF axle; Fits 1987-1995 Jeep Wrangler, front outer with Spicer 30-AF axle; Fits 1995-1998 Ford F-250, front outer with Spicer 50.5 axle; Fits 1992-1993 Ford F-250, front outer with Spicer 50.5 axle; Fits 1988 Ford F-250, front outer with Spicer 50.5 axle; Fits 1983-1985 Ford F-250, front outer with Spicer 50.5 axle; Fits 1980 Ford F-250, front outer with Spicer 50.5 axle.

What It Helps Address

• Gear oil seepage at the differential pinion area
• Contamination from dirt, water, and road debris
• Seal wear that can lead to driveline fluid loss
• Maintenance needs on aging axle assemblies
• Service replacement for worn front outer or rear outer seals

Installation Notes and Tips

Verify axle type, position, and dimensions before installation. Clean the housing bore and shaft sealing surface thoroughly, and inspect the pinion area for wear or scoring that could affect seal life. Confirm the seal orientation during installation so the sealing lip seats correctly against the shaft.

For best results, match the application to the listed axle configuration, such as Spicer 30-AF, 44-1F, 44-3F, 44-8F, 44-9F, 44-FBJ, 44-1HD, 44-3 Axle, 44-5F, 44-6F, 44-6FHD, 44-7F, 44-8F, 44-9F, 50.5, and related supported variants shown in the fitment data.

Quality Assurance

InMotion manufactures this seal with precision sizing and durable materials selected for differential service. The combination of fluoro-elastomer, nitrile sealing material, and a formed seal case supports consistent fitment in the listed applications.