What is the Pinion Seal all about?

In vehicles that have the rear wheels as drive wheels, drive shafts, differentials, and transfer cases are used to transmit power from the engine and transmission to the wheels. In a front-wheel drive setup, CV axles join the transmission directly. However, in rear, all and four-wheel drive setups, that’s not the case. Depending on the make and model you own, you may have a single driveshaft and differential, a front and rear differential (in the case of all-wheel drive) or some other setup.

In these systems, driveshafts are used to transmit movement/power from the transmission to one or more differentials. While they’re all different, they do have a few similarities. Each differential will have a pinion shaft – a short shaft that attaches to the pinion gear inside the differential and terminates in a flange. The pinion shaft attaches to the driveshaft.

Each pinion shaft will have a pinion seal, which is used to ensure that fluid does not leak out of the differential past the pinion shaft. Depending on the setup, you may have a rear pinion shaft, or a front and rear pinion shaft.

Keep in mind:

• The rubber pinion seal will wear and eventually need to be replaced.
• Pinion leaks should be inspected at each service interval.
• Low fluid in the differential can damage gears.

How it's done:

• The vehicle is lifted and supported on jack stands and the drive shaft is removed
• The defective pinion seal is removed
• The new pinion seal is installed
• The drive shaft is installed and the vehicle is removed from jack stands
• The vehicle is started and checked for steering operation

Our recommendation:

Whether you have a four-wheel, rear-wheel or all-wheel drive vehicle, it’s vital that you keep your differential in good working order, and that means maintaining the right fluid level. As the fluid level drops, gears wear and friction increases. We highly recommend having any pinion leaks inspected by our expert mechanics as soon as possible.

What common symptoms indicate you may need to replace the Pinion Seal?

• Fluid leaking at the pinion shaft
• Low fluid in the differential
• Differential whining during operation (a sign of low fluid and/or damage)

How important is this service?

Without an operational differential, your vehicle can’t be driven; therefore, it’s vital that you maintain the right fluid level. Any leak can quickly drop the fluid to unsafe levels, and serious pinion leaks can cause problems very quickly. Have your vehicle serviced by our expert mechanics, who will keep an eye on your entire vehicle during regular maintenance and diagnose any differential fluid leaks.