CV axles also referred to as joints are a modern drivetrain component commonly found on front wheel or all-wheel drive vehicles. They serve the purpose of transferring uniform torque at constant speed from the vehicle’s transmission and differential to the wheels so that they can propel the vehicle forward through a wide range of angles. The drive axels must transmit power from the engine to front wheels that must drive, steer, and cope with the severe angles caused by the up and down movement by the cars suspension. To accomplish this, these cars must have a compact joint that ensures the driven shaft is rotated at a constant velocity regardless of the angles. The joint is lubricated with grease and covered in a rubber boot to protect it from dirt and debris.

Because the CV axles are the direct link that transfers the power of the engine to the wheels, they are subject to high amounts of stress over time and will eventually wear out and require replacement. When they do wear out, the CV axles usually will produce a few symptoms that can alert the driver that they require attention.

Loud clicking noises when turning

One of the most common and most noticeable symptoms of a bad or failing CV axle shaft assembly is a very loud clicking noise when turning the steering. Due to the high stress levels put upon the cv joints they get worn with time and become stiff with less flexibility. The clicks may become louder or more pronounced during sharper and faster turns, and will be heard on the side with the faulty CV shaft

Grease on edge of tire

Another symptom of a problem with the CV axle shafts is grease on the inside edge of the tire or along the undersides of the vehicle. This is usually caused by a torn CV boot leaking grease, and it being tossed around while the axle turns. A leaky boot will eventually lead to CV joint failure, as dirt and debris will get into the boot and damage the joint.

Excessive vibration when driving

Another symptom of a bad CV axle is excessive vibrations from the axle when driving. If a CV joint or axle shaft is damaged in any way that affects its balance while rotating, it will cause the shaft to vibrate excessively while operating the vehicle. The vibrations may oscillate in speed, or become more pronounced as vehicle speed increases. Excessively vibrating CV shafts can interfere with the handling and ride characteristics, and to the overall safety and comfort of the vehicle. Usually the CV axle will need to be replaced if it is damaged enough to cause vibrations.

CV axles serve as the final link between the engine and the wheels. They serve the important function of transferring the torque from the drivetrain to the vehicle’s wheels in order to move the vehicle.