Constant Velocity Axles, known as CV Axles, transfer the power from the transmission or differential to the drive wheels.
The design allows for constant power to be delivered to the wheels while the wheels turn for steering and move up and down over uneven road surfaces.
The gears that allow for this transfer of power are protected by a rubber boot that holds in the necessary lubrication.
CV Axles are durable and built for a long service life. The most common reason for failure is a tear in the rubber boot that allows for the lubricating oil to escape and dirt and moisture to get into the gears.
A surprisingly small amount of dirt and/or moisture along with a lack of lubrication can do significant damage in a short period of time. Therefore, the best repair advice is to replace any CV Axle that has a failed boot. The alternative is to replace the boot, repack the grease and hope for the best. At that point a failure is far more likely to occur which puts you in the position of paying twice for the same repair.
What are the symptoms of a failing CV Axle? When the boot fails, grease will leak out. That’s typically the first symptom, and the symptom most people will notice. The grease may fly out in any direction, sometimes ending up on the exhaust or other hot surface resulting in a burning smell.
As damage occurs to the CV Axle, a clicking noise when turning is a primary symptom. Sometimes the clicking is louder turning one direction than another. Waiting until the CV Axle fails completely will result in a breakdown that can strand you miles from a repair facility.
Fortunately, CV Axles are commonly available, and replacing them is not a major repair. A qualified repair facility can diagnose and replace a failing CV Axle in a timely manner.