If you've ever gotten stuck in your 1999-2003 Ford F250/350 and needed 4-wheel drive, then a transfer case is what helped get you out. 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. It is responsible for transferring power to the front wheels and rear wheels in 4-wheel drive systems. 4-wheel high is used in high-speed settings such as dirt or snow, whereas 4-wheel low is used in low-speed settings like steep rocky hills where maximum wheel torque is required. 4-wheel high will maintain the same gear ratio as 2-wheel drive and is for high-speed situations such as driving on dirt or snow-covered roads.
The Transfer Case is designed to be used in off-road or low-traction situations and is not recommended to be used on dry pavement where wheel slip is not possible. 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. Shop XDP's large selection of Transfer Case products from the top brands such as Merchant Automotive, PPE, Sun Coast Converters, and Dorman. Since transfer cases lock the front and rear axle together, the wheels are unable to spin at different speeds making turning and cornering on dry pavement difficult. Wheel slip is possible in loose terrain, alleviating any binding that can occur on dry pavement. Transfer Cases generally are very strong from the factory and do not require internal upgrade unless the vehicle is used for extreme off-roading or racing.