FAG SS3857 Differential Pinion Seal - Rear

FAG SS3857 Differential Pinion Seal

The FAG SS3857 differential pinion seal is built for driveline sealing performance where the pinion shaft enters the differential housing. It uses a metal shell, spring, auxiliary lip, and inner shell design with polyacrylate sealing material to help maintain a tight seal under demanding operating conditions. This FAG SS3857 seal is a direct-fit style service part for applications that require precise bore and outside diameter control.

Key Features

• Part number: SS3857
• Differential pinion seal for driveline and axle service
• Seal type: metal, spring, auxiliary lip, inner shell
• Sealing material: polyacrylate
• Bore diameter: 4.249 in. (107.925 mm)
• Seal outside diameter: 4.254 in. (108.052 mm)
• Seal width: 2.75 in. (69.85 mm)
• Engineered to help keep lubricant in and contaminants out

Detailed Description

FAG designs sealing components to meet vehicle manufacturer specifications, and the SS3857 follows that approach with dimensions and materials selected for differential pinion service. The seal’s metal shell supports stable fitment, while the spring-loaded sealing edge and auxiliary lip help maintain contact at the shaft surface. In applications such as Ford F-150 and Chevrolet Silverado driveline service, a properly matched pinion seal helps preserve differential lubricant and protect internal components from dirt, dust, and moisture. This part cross-references Standard Ignition 27601 for the same application.

What It Helps Address

• Differential gear oil seepage at the pinion shaft
• Contamination entering the differential housing
• Loss of lubricant from worn or damaged sealing surfaces
• Noise or wear caused by low differential fluid level
• Service replacement for a leaking pinion seal on Ford F-150 or Chevrolet Silverado driveline repairs

Installation Notes and Tips

Verify bore diameter, seal outside diameter, and width before installation to confirm the seal matches the housing and shaft requirements. Inspect the pinion yoke and sealing surface for grooves, corrosion, or wear that can affect sealing performance. Clean the housing thoroughly and install the seal squarely to avoid distortion. For Ford F-150 and Chevrolet Silverado applications, confirm the exact axle and driveline configuration before ordering the FAG SS3857.

Quality Assurance

FAG sources sealing components to meet manufacturer-specific requirements and works with suppliers to maintain its quality standards. The SS3857 is built for precise dimensional control and material consistency in differential sealing service.