CV Axle (CV Joint / Drive Axle)

What it does

In a front-wheel-drive or all-wheel-drive car, the CV axle is the shaft that delivers engine power from the transmission to the front wheel while also letting the wheel steer left and right and move up and down with the suspension. The secret is the CV joints — ball-and-socket joints at each end of the shaft packed with thick grease inside a rubber boot. The grease is the key: when the boot cracks, grease leaks out, dirt gets in, and the metal balls inside grind against each other. This is why you hear clicking during turns — the joint needs smooth grease to handle the extreme angle.