What a CV joint actually does
A CV joint sends drive torque to the wheel while the angle changes. Outer Rzeppa, inner plunge. Crack the boot and the joint dies. It is not a U-joint.
The myth is that the click is “just grease” — or that a U-joint and a CV joint are the same part. What a CV joint actually does is send drive torque to the wheel while the angle keeps changing: steering lock, suspension travel, constant rotational speed.
A U-joint is crosses in cups. Speed rises and falls every revolution when that joint is bent. A CV joint is built so the speed stays even. The outer one is usually a Rzeppa — balls in a cage. The inner one is usually a tripod that plunges so the shaft can grow and shrink as the wheel moves.
The rubber boot is not decoration. It keeps grease in and grit out. Crack it and the joint dies — the click on lock is the balls running dry. It is not the differential. It is not the axle shaft alone. The shaft is the tube. The joints are the ends that let the wheel steer and bounce without chopping the drive.
