If you've ever gotten stuck in your gas vehicle and needed 4-wheel drive, then a transfer case is what helped get you out. It is responsible for transferring power to the front wheels and rear wheels in 4-wheel drive systems. Transfers cases typically have two 4-wheel drive settings, a high and low gear ratio for different situations. Contained inside the transfer case is a set of gears and chains that are engaged or disengaged depending on the drive mode selected. The Transfer Case mounts to the back of the transmission and is what the front and rear drive shafts connect to. 4-wheel low is for low-speed situations where maximum torque is required such as driving up a steep rocky hill or pulling out a stuck vehicle.
It is highly recommended to not engage the transfer case for anything other than off-road or low-traction situations. In some applications an external brace can be added to increase the structural rigidity of the transfer case to prevent damage from high torque loads or twisting. When engaged in 4-wheel drive the transfer case and drivetrain need some wheel slip to prevent binding or damage. XDP carries a wide selection of Transfer Case products available from Dorman, Merchant Automotive, PPE, Sun Coast Converters, and more. A Transfer Case typically does not require internal upgrades or modification unless the vehicle will be used for extreme off-roading or racing applications. When you shift the Transfer Case into 4-wheel drive, it locks the front and rear axles together so that they spin at the same speed.
