BMW 640i xDrive CV Axle / Shaft Assembly Replacement at your home or office.

What are CV Axles and how do they work?

All front wheel drive and all wheel drive cars use CV axles. “CV” is short for constant velocity. You have your engine and transmission in the car. Which are mounted to the body of the car and cannot move up and down with the suspension. [AB2] Then you have the suspension and wheels on the car, which can go up and down to absorb bumps and on the front of the car, steer. The CV axle is a shaft that has two constant velocity joints at either end of it. One end comes out of the transmission, the other end mounts in the wheel hub. The two joints let the axle continue to spin as the suspension travels up and down and you steer the car. An fwd car will have one for both the passenger side and driver’s side. An AWD car will have the same, but additionally two in the rear of the car. Each of the CV joints is covered by a rubber accordion looking boot that holds the grease in and keeps dirt and water out. Because of mileage, environment, and just wear and tear these boots can rip. When they rip, grease escapes, dirt, and water get into the CV joint and can make it wear out. This will often cause a clicking noise from the front of the car while turning.