A half shaft, also called an axle, transmits power from the transmission to propel the vahicle's wheels.
Each half shaft has two constant-velocity (CV) joints, which are packed with grease and encapsulated by a rubber cover known as a CV boot. If the CV boot becomes damaged, grease no longer lubricates the CV joints, allowing dirt and debris to enter the joint, causing wear. If this happens, the half shaft may also need to be replaced with a new or remanufactured half shaft.
If a clicking sound (that increases with the speed at which a vehicle takes a sharp turn) can be heard, this strongly suggests that a half shaft is worn and in need of replacement.
To replace the half shaft, the wheel is removed and the suspension is disassembled to the point where the half shaft can be withdrawn from the transmission and suspension. The new half shaft is installed, and the suspension reassembled.