Drive shafts transmit the power from the transmission to the wheels. But because the transmission is fixed to the frame of the vehicle and the wheels need to be able to turn, bounce and flex, the drive shafts must have flexible joints that allow this variable movement while allowing you to accelerate during all of these conditions. For this reason, drive shafts were built as a long shaft with two universal joints at each end called constant velocity joints (CV joints). These joints are covered by corrugated rubber cone-shaped boots that keep water, dirt and corrosion from damaging the joints. Most of the time the outer boots are the first to wear and develop deep cracks in the valleys of the corrugation. After these cracks split open the joint centrifugally slings the grease out of the joint and onto the surrounding components. This creates two issues. The first is that the joint is almost immediately ruined and the second is that the grease gets slung onto the flexible brake hoses or other rubber brake parts. The rubber on the flexible brake hoses is not made to withstand the solvents in the drive shaft grease and the rubber begins to soften and loose integrity.