CVjoints

CV joints, or constant-velocity joints, are mechanical joints used to transmit power from the drivetrain to the wheels at varying steering angles and suspension movements while maintaining a roughly constant rotational speed. They allow the drive shafts to articulate with minimal speed fluctuation as the wheels turn and the suspension travels, improving smoothness and steering response.

The most common type is the Rzeppa joint, which uses an inner race attached to the axle, an outer race on the drive flange, a cage, and six balls that ride in special tracks to transfer torque. Another widely used design is the tripod joint, which employs three rollers mounted on a yoke and is typically found on inner or outer joints in some front-wheel-drive layouts. Some applications use alternative ball-and-socket configurations or other hybrid designs. CV joints are usually paired with a protective boot filled with grease to seal the joint and allow for lubrication during movement.

Key components include the inner and outer races, rolling elements (balls or rollers), a cage to maintain spacing, and a grease-filled boot that keeps contaminants out. The joint begins to fail when the boot splits or cracks, allowing grease loss and dirt ingress, which accelerates wear. Faults manifest as clicking or clunking noises when turning, vibration at speed, or visible grease around the boot.

Commonly used on front-wheel-drive and many all-wheel-drive vehicles, CV joints are designed for high angular movement but can wear over time, typically requiring boot replacement or axle replacement when damaged. Regular boot inspection helps extend service life.