CVjoint

A CV joint, short for constant-velocity joint, is a mechanical linkage that transmits torque from a drive shaft to a wheel or another shaft at a varying angle without a significant change in rotational speed. It is commonly used on front-wheel-drive and many all-wheel-drive vehicles to accommodate steering and suspension movement.

CV joints are typically arranged as a pair on each drive shaft: an inner joint connected to the transaxle and an outer joint near the wheel. They are sealed by protective boots, typically made of rubber or synthetic material, filled with grease to keep dirt out and lubricant in. The boots accommodate axle movement and wheel articulation.

Two common types are the ball-type (Rzeppa) outer joint and a tripod or phasing inner joint. The Rzeppa joint uses a set of balls riding in grooves between a fixed inner race and rotating outer housing, providing constant velocity through wide steering angles. The tripod joint uses three rollers on a trunnion to accommodate axial movement and provide smooth operation under high angular displacement.

In operation, the CV joints transmit power with nearly constant speed as the drive shaft angles change during steering and suspension travel. This reduces torque ripple, vibration, and driveline noise compared with single universal joints, and enables efficient power delivery in modern front- and all-wheel-drive layouts.

Common failure signs include a torn or leaking CV boot, which allows dirt in and grease out, leading to accelerated wear. Audible symptoms are clicking or popping when turning, clunking noises at certain speeds, or vibrations. Replacement typically involves a new joint assembly and boot, rather than boot repair alone.