The Transfer Case

This is a vital component commonly found in all wheel drive and four wheel drive vehicles. It is connected to the rear and front axles and the vehicle’s transmission through a drive shaft. Two wheel drive vehicles do not require a transfer case. This is due to the fact that they are equipped with a driveshaft that goes directly from the transmission into the drive wheels.

Types of Transfer Cases

Drive Type

Chain driven

Chain driven cases utilize a chain that usually drives only one axle. However, this type of vehicle component can also drive both axles. These cases are lighter and quieter than gear driven ones. They are commonly used in vehicles such as full size trucks, compact trucks, sports utility vehicles, and Jeeps.

Gear driven

Gear driven transfer cases can utilize sets of gears in order to drive both the rear and front driveshafts, or only the front driveshaft. These are generally heavy and strong units that are commonly used in large trucks. However, there are several gear drive cases that are manufactured for passenger cars.

Shift Types


These cases are equipped with dash mounted buttons or switches that have front sealed automatic locking drive flanges or an axle hub. In order to engage a four wheel system, a car must be moving at very low speeds. The speed that a 4×4 can be engaged at also depends on the vehicle. This is only found with a four wheel drive high option. Additionally, a car must be stopped in order to engage a four wheel drive low option. The transmission should be shifted to neutral. After doing this, the four wheel drive low option can be used.


These cases are equipped with a selector lever. This lever is found on the driver’s side floor transmission projection. It also has either a two manual front axle center selection or two sealed auto front axle locking hubs. In order to engage a four wheel drive system, a vehicle must be running at low speeds. To engage a four wheel drive low option, the car must be completely stopped. At the same time, the transmission must be put into neutral. After this, the four wheel drive low option can be selected.

Housing Type

Independent or Divorced

Independent cases are completely separated from a vehicle’s transmission. They are commonly bolted to the car’s gear box output shaft. The very short driveshaft connects the transfer gearbox to the rear and front differential. These transfer gearboxes are commonly utilized on long wheelbase vehicles that include military or commercial trucks.


A married transfer gearbox is bolted directly to a vehicle’s gear box. This transfer gearbox is an integral component of a gearbox. These two components also share the same housing. This transfer gear-case is commonly found in some four wheel drive cars and recent Subaru products.

Rebuilt Cases

Sometimes, these cases can bog down due to excessive use or old age. Buying a brand new case can be financially burdensome. This is the reason why many car owners consider rebuilt cases. Rebuilt cases can be similar or much better than brand new transfer cases. At the same time, only broken parts of a transfer gearbox are replaced.

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