Timken 4278 Differential Pinion Seal - Rear or Rear Outer

Timken 4278 Differential Pinion Seal

Timken 4278 is a differential pinion seal built for rear axle service on a wide range of Ford, Lincoln, and commercial applications. It uses a precision sealing design to help keep gear lubricant in the axle housing while blocking dirt and debris from entering the seal area.

Key Features

• Precision sealing design for differential pinion service
• Reinforced outer case helps resist installation damage
• Ribbed rubber inner diameter helps seal minor spindle imperfections and improve seating
• Internal contamination exclusion system helps reduce debris intrusion
• Vent holes promote lubricant flow around the seal lip to help manage heat

Detailed Description

This Timken differential pinion seal is engineered for rear axle applications where reliable lubricant retention matters. It is used in Ford F-150, Ford Expedition, Ford F-250 Super Duty, Ford F-350 Super Duty, Lincoln Navigator, and related models with the listed ring gear and axle configurations. Timken 4278 is a direct-fit service part for rear differential pinion sealing on many 1998-2024 applications, including rear and rear outer positions where specified.

This part cross-references AMS Automotive 4278 and Baldwin 18024 for the same application.

What It Helps Address

• Gear oil leakage at the differential pinion area
• Contamination entering the axle seal surface
• Heat buildup around the seal lip
• Seal wear caused by minor surface imperfections
• Service replacement for worn rear differential pinion seals

Installation Notes and Tips

Verify axle type, ring gear size, and position before installation. Fitment includes rear applications for 9.75-inch and 10.25-inch ring gear setups, plus select 10.5-inch ring gear configurations on Ford Super Duty and van platforms. Confirm the exact vehicle listing for your Ford F-150, Ford Expedition, or Lincoln Navigator before ordering, especially on models with non-limited-slip or specific axle notes.

Quality Assurance

Timken oil and grease seals are built with reinforced sealing construction and contamination control features to support dependable service in driveline applications.