The Role Of The Transfer Case

by | Oct 2, 2014 | Automotive

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If you have a four-wheel or all-wheel vehicle then your car or truck as a transfer case. It is a part that connects to the transmission and then also to the front axles and the rear axles by the drive shafts. It is somewhat similar to a differential in that it controls the rotation of the front and rear wheels.

What it Does
The transfer case is an important part of your vehicle’s drive system that tells the vehicle, either automatically or by manual shifting, to drive with two or four wheel drive. In some vehicles the transfer case can also be controlled by a switch that allows you to engage the four wheel drive component or disengage to go back to two wheel drive.

In the case of all wheel drive cars and trucks, which are becoming increasingly more common, the transfer case is set to always use all wheels. This cannot be changed by the driver either through a shifter or a switch.

The transfer case in any vehicle will either be driven by gears, which is less common, or by a chain, which is most common. The transfer case is filled with a special fluid, gear oil, which provides lubrication to all moving parts. This oil will break down over time and should be drained and replaced following your vehicle manufacturer’s recommendations.

In addition there are seals and bearings that can need to be replaced, often on higher mileage vehicles or those that are used for off-road over rough terrain. Routine maintenance of the transfer case can help to detect these problems before they cause more significant damage.

Potential Signs of Problems
The most common signs of failing or damaged transfer case include a heavy grinding or grating sound coming from the underside of the vehicle. Another common sign, with or without the sound, is the inability to get the vehicle to shift into 4-wheel or all-wheel drive or to switch or shift out of those drives.

During a fluid change your technician will also notice that the fluid in the transfer case is low or very dark in color. Sometimes simply draining the fluid and refilling can correct the problem if the parts have not been damaged. Let us check your transfer case and complete a basic maintenance service. To learn more go to

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