InMotion WS231003 Engine Crankshaft Seal - Rear

Rear Differential Pinion Seal for BMW and More

The InMotion WS231003 is a rear differential pinion seal built with nitrile material for a precise sealing surface and dependable resistance to contaminants. It helps maintain a tight barrier at the pinion area, supporting leak control and protecting internal differential components in demanding driving conditions.

Compatible With select BMW, Land Rover, Rolls-Royce, Bentley, Ford, and Mazda rear applications, this seal is a direct-fit service part for vehicles such as the BMW M3, BMW X5, and BMW 760Li. The WS231003 is engineered around the specified shaft and housing dimensions for accurate sealing performance.

Key Features

• Nitrile construction for sealing durability
• Inside diameter: 3.937 in.
• Outside diameter: 4.932 in.
• Thickness and width: 0.472 in.
• Shaft diameter: 3.937 in.
• Housing bore: 4.921 in.
• Rear differential pinion seal application
• Part number: WS231003

Detailed Product Description

InMotion WS231003 is designed as a rear differential pinion seal for vehicles that require a precise fit at the pinion shaft interface. The nitrile sealing material is selected for its ability to maintain contact and help block moisture and debris from entering the differential assembly. By preserving the seal at this critical point, the part supports cleaner internal operation and helps reduce fluid loss from the differential housing.

This seal is listed for a wide range of rear applications, including BMW 740i, BMW 750iL, BMW M5, BMW X5, BMW Z8, Land Rover Range Rover, Rolls-Royce Silver Seraph, Bentley Arnage, Ford Ranger, and Mazda B2200. The WS231003 part number is also useful when cross-checking service records or ordering by reference.

What It Helps Address

• Differential fluid seepage at the pinion area
• Contamination from road debris and moisture
• Wear at the pinion seal contact surface
• Noise or drivability concerns related to low differential fluid
• Service replacement for rear differential maintenance

Installation Notes and Tips

Confirm the rear application, shaft diameter, and housing bore before installation. Inspect the pinion yoke and sealing surface for wear, scoring, or corrosion, since surface damage can affect seal performance. Clean the housing thoroughly before installing the new seal, and verify proper alignment during assembly to avoid premature leakage.

Use the vehicle fitment data to confirm coverage for your application. This part fits 2010-2015 BMW 760Li, rear; 2008-2013 BMW M3, rear; 2000-2013 BMW X5, rear; 2003-2005 Land Rover Range Rover, rear; and other listed rear differential applications. Part number WS231003 should be matched to the vehicle’s original seal dimensions before service.

Quality Assurance

InMotion manufactures this seal with precision-focused dimensions and nitrile material selection to support reliable differential sealing in service applications. The design centers on maintaining a secure barrier at the rear pinion location for the listed BMW, Land Rover, Rolls-Royce, Bentley, Ford, and Mazda vehicles.