Your four-wheel drive is composed of elements. One of the elements that is very important is your transfer case.
First off though, let’s explore what a four wheel drive is.
Four Wheel Drive and a Transfer Case

According to this article excerpt:
Four wheel drive refers to vehicles that have a differential that may or may not be lockable, between the front and rear axles, meaning that the front and rear drive shafts will not rotate at different speeds. This provides maximum torque transfer to the axle with the most traction, but can cause binding in high traction, tight turning situations. They are also either full-time or part-time 4WD selectable.All wheel drive refers to a drive train system that includes a differential between the front and rear drive shafts. This is usually coupled with some sort of anti-slip technology that will allow all wheels to spin at different speeds, but still maintain the ability to transfer torque from one wheel in case of loss of traction at that wheel. All wheels are engaged to the drive full-time… [READ MORE]
In a way, a four wheel drive is kind of an additional transmission that allows you to have better control over rougher terrain. In a place that is heavily urban, a four wheel drive goes largely unused. In a rugged area like Arizona, however, where even now, some roads aren’t paved, a four wheel drive vehicle can be quite useful. A system like four wheel drive also needs something to help it move power between wheels, and that is your transfer case.
A Transfer Case and it’s Repair
The transfer case transfers power from the transmission to both the front and rear axles. Some transfer cases use gears, but many more transfer cases nowadays are chain driven. Like any engine part, sooner or later you are going to need to repair it. And make no mistake, transfer case repair is not something most people can do.
Trail Transmission is an expert in transfer case repair, as well as fixing transmissions, and rear differentials.
Trail Transmission
11240 East Apache Trail
Apache Junction, AZ 85120-3529
(480) 986-7367
https://trailtransmission.com/