For those people who own a vehicle that is equipped with all-wheel drive or four-wheel drive, the vehicle uses a transfer case in order to split up the motion so you get the rear and front motion. Within this transfer case are two shafts. One of these shafts is kept in place by a bearing, whose sole job is to keep it from bouncing and moving around. Should it move around it would end up leaking oil. This bearing is called the front output shaft bearing.

In order for this front output shaft bearing to work properly it requires lubrication. The lubrication is taken from the internal transfer case oil. Over time it can start to lose its lubrication, which will end up affecting how it operates. It can also become worn down over time. Should either of these happen, it will require a trained mechanic to properly diagnose the situation and either repair or replace the part. This is definitely not a DIY kind of repair.

While there is no set mileage for the lifespan of the front output shaft bearing, you can help to increase its life by having it inspected on a regular basis. A good idea is to change the transfer case oil so it is sure to get good quality oil, and enough of it. Here are some signs you can watch for that may signal the failure of your front output shaft bearing.

  • If you begin to hear noises coming from your drive train, it's time to get your vehicle looked at. You won't want to delay as this can be a safety issue. Should the bearing seize up completely, it may result in your wheels locking up.

  • If you're getting grinding and vibration from the front of your car, then this is another sign that the front output shaft bearing is faulty.

  • Be sure to keep your eye out for oil leaks coming from the front area of your transfer case. This again signals that your front output shaft bearing is likely faulty.

The front output shaft bearing is an essential component of your 4x4 system. Without it your vehicle won’t be able to work properly and you even risk your front wheels locking up right in the middle of driving. If you’re experiencing any of the above mentioned symptoms and suspect your front output shaft bearing is in need of replacement, get a diagnostic or book a front output shaft bearing replacement service with a certified mechanic.

This article originally appeared on YourMechanic.com as How Long Does a Front Output Shaft Bearing Last? and was authored by Valerie Johnston.


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