All front wheel drive and all wheel drive cars use CV axles. “CV” stands for constant velocity. Your engine and transmission are mounted to the body of the car such that they don’t move up and down with the suspension. The suspension and wheels, on the other hand, do move up and down to absorb bumps. The CV axle is a shaft that has two constant velocity joints at each end. One end comes out of the transmission and the other end mounts in the wheel hub. The two joints let the axle continue to spin as the suspension moves up and down and while you steer the car. A front wheel drive car will have a CV axle on both the passenger side and the driver’s side. An all wheel drive car will an additional two in the rear of the car. Each CV joint is covered by a boot that looks like a rubber accordion. It’s function is to hold the grease in and keep dirt and water out. Mileage, road conditions, and normal wear and tear can cause these boots to rip. When they rip, the grease leaks out and dirt and water get into the CV joint, causing it to wear out. This wearing out of the CV joint often creates a clicking noise in the front of the car while turning.
The constant velocity (CV) joint sends power from the transmission to the wheels (typically the front wheels). The CV boot is a flexible rubber boot that protects the joint, preventing water and dirt out of the joint, and keep grease inside of the CV joint.
There is prescribed time to change CV axles. Overtime, they simply break, and unless you get your car regularly examined by a mechanic, you might not know that you car had torn boots which will lead to your CV axles getting damaged.
The car mechanic will: