All of the drive power for your vehicle must pass through the Kia CV Axle Shaft for the wheel to move. The CV axle shaft has a knuckle at one end that is part of the CV joint in the front wheel drive units of your Kia. The other end of the shaft is connected to the output shaft of the transmission.
With the CV axle shaft connected to the CV drive shaft is what forms the CV joint. This is the most common component in the drive section as known by most owners of Kia's and other vehicles. It is the CV joint that is covered by the CV boot which can be problematic if the owner of the Kia does not do their periodical inspection of their vehicle.
The problem is avoidable if the joint or knuckles of the CV axle shaft and the CV driver shaft are kept lubricated. This is the purpose of the CV boot. It is a polymer component that fits around this junction holding in the ball bearing grease so the CV joint can be continuously lubricated.
When the CV boot become ripped or torn, the grease lubricating the Kia CV axle shaft and drive shaft is exposed to the environmental conditions on the exterior of the vehicle. This includes moisture and debris that can enter this area of your vehicle causing the onset of premature aging or wear on the components that are exposed.
The driver of the vehicle will notice there is a problem when they place the transmission in drive and hear a bang when the drive unit is engaged. This is the wear in the CV axle shaft slamming into the CV drive shaft. At that point it is too late to just replace the CV boot.