The CV axle (also called CV axle shaft and axle shaft) is responsible for transmitting torque from the transaxle or differential to the wheels, enabling the vehicle to be driven forward. There are two CV joints on its inner and outer ends that allow the CV axle shaft, which connects to the wheel hub, to transmit power without being affected by different road conditions. The joints are protected by a rubber boot filled with grease.
Together, the shaft, the joints, and the boot make up the CV axle assembly. These components work together as a system that ensures an efficient and comfortable ride. Without the CV joints, the axles would break or bend whenever the vehicle drives over bumps or turns a corner. So it is important to inspect and maintain the CV joints properly because they keep the CV axle protected from strong impact forces.
The CV axle is mainly used in front-wheel-drive vehicles to transfer engine power to the two drive wheels. Some late-model vehicles come equipped with independent rear suspension and many four-wheel and all-wheel vehicles also have CV axles.
What Causes a CV Axle to Fail?
CV axles and joints may wear faster than normal if the CV boot is ruptured. When this happens, the joints lose grease and are no longer properly lubricated.
Moisture, water, and other road debris can also get inside the ruptured boot, making the CV joints vulnerable to faster wearing.
The joints will also fail prematurely if they’re put at an extreme angle because the vehicle’s suspension is modified. For example, a lifted truck may go through CV axles quickly.
In other instances, the CV joints may simply wear out over time.
How to Tell if Your CV Axle is Bad
There are quite a few things that can go wrong with the constant velocity (CV) axle assembly. Leaking grease and normal wear can cause its parts to deteriorate. How will you know if your vehicle’s CV assembly is failing? Below is a list of bad CV axle symptoms:
Clicking noise when turning
When the CV axle gets worn down due to constant use, it can loosen the joints. As the outer joints become unstable, they may produce a distinct sound that some people describe as a click or a pop. This sound is most noticeable when you make sharp or fast turns while driving around corners. You’ll hear the unusual clicking noise from the side of the vehicle with the faulty CV shaft.
Clunking sound when decelerating or accelerating
You may also hear unusual clunking or knocking noises from the inner CV joint assembly when you decelerate or accelerate.
The sound may also come from an entirely different source but hearing it should be a cause for concern.
Grease on the underside of the vehicle
The CV boot is what keeps the CV joints lubricated so they can function properly. It’s made of high-quality rubber that doesn’t rupture easily.
However, if the boot gets damaged, the grease inside it may fling onto the underside of the vehicle as the axle turns.
Vibration while driving
A damaged axle shaft or CV joint can affect the balance of the whole assembly as it rotates. When this happens, the shaft may vibrate excessively. These vibrations can intensify as you accelerate.
What Should You Do In Case You Have a Faulty CV Axle?
You may lose control of your vehicle if your CV joints are worn out. This can potentially lead to accidents and personal injury. As such, worn CV joints should be replaced immediately.
If you notice any of the symptoms listed above, it would be best to immediately inspect the CV joints. Once you’ve confirmed that the issue is caused by worn CV joints, you will need to get a replacement. Aftermarket CV axle assemblies range from $26 to $9,000, while aftermarket CV joints cost anywhere from $60 to $800.
If you plan on doing the repairs yourself, you may need specific equipment such as a durable torque wrench/breaker bar and an appropriate socket. As for repair instructions, it’s best to consult a vehicle-specific repair manual or database. However, if you don’t have much repair experience, you can have a certified mechanic do the job for you.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.