A bad CV axle will make itself heard, quite literally. If you’ve already experienced a bad CV axle in the past, you already know about the infamous clicking noise. What many don’t know is that a bad CV axle shows more symptoms than this. Some of are much worse than the displeasing clicking sound. Before we discuss the symptoms, let’s understand the role of a CV axle and what could cause it to go bad in the first place.

CV axles don’t get the credit they deserve. They are partly responsible for the affordable front-wheel drive car segment that exists today. Although fairly simple compared to other mechanical components, they serve a truly important purpose. CV axles are key drivetrain components and are mainly responsible for transmitting power from the engine to the wheels.

Importance of a CV Axle

Truth be told, transmitting or transferring power from the engine to the wheels sounds like a basic task. However, it’s how CV axles do it that makes them special. To be more specific, this type of axle can reliably transfer power while being unaffected by the movement of the wheel. When we say movement, we aren’t only referring to the direction it’s turning in, but every other change in direction. The CV in CV axles stands for constant velocity as the input and output speed remain unchanged regardless of the operational angle.

If you read our guide dedicated to tie rod ends, you know that they are responsible for turning the wheels from side to side. On the other hand, suspension components, like shock absorbers, allow the wheels to move upwards and downwards. In other words, the front wheels are capable of moving in various directions at the same time. A CV axle is engineered to work while remaining unaffected by the wheel geometry constantly changing.

CV Axles — How Do They Work? 

To better understand CV axles, it’s important to get an idea of the parts it’s made of and the roles they serve. An average constant velocity axle is made of two joints, namely, inboard and outboard joints. They are called inboard and outboard joints because of their location with respect to the final drive or the hub of the wheel. The final drive is part of the transmission and the component responsible for sending the power or torque out of the engine.

The outboard joint is also referred to as the fixed ball joint. In most cases, it consists of six ball bearings in between the housings towards the inside and outside. These bearings are kept in position with the help of what is known as a cage. It also features machined tracks or grooves that let the bearings slide and this is what makes CV axle so impressive. 

As you’d expect with metal-on-metal movement, there has to be lubrication at all times. Most joints of this type use lithium-based grease as a lubricant with a flexible rubber boot to help it protect it from the elements. When it comes to the inboard CV joint, it’s quite similar to the aforementioned outboard joint aside from the fact that it doesn’t need to account for changing steering angles. That said, it still has to be able to handle suspension movement.

While CV axles are commonly linked with front-wheel drive vehicles, they are also used on many rear-wheel drive and all-wheel drive vehicles today. Regardless of the configuration, the inboard CV joint connects to the transmission, while the outboard side attaches to the outboard joint.

Main Symptoms of a Bad CV Axle

As mentioned at the beginning, a bad CV axle will be quite evident. It’s fairly easy to spot if you know the symptoms. If you spot any of these symptoms and need a new CV axle, check our offer for quality replacement options. We stock parts from genuine, OEM and quality aftermarket sources!

Leakage

In the majority of cases, one of the earliest signs of a bad CV axle will be a grease leak. A grease leak is what causes most other symptoms. As mentioned earlier, a CV axle uses a rubber boot to preserve its lubricant. 

These rubber boots are exposed to all sorts of dirt and debris which can cause a tear. If this happens, the lubricant will escape through the tear when the axle rotates at high speed. The lubricant which is essentially grease then makes its way to the inside of your wheels and wheels. 

Noise

Once you have a bad CV axle, it will make a clicking sound that’s hard to miss. This sound is usually heard while turning. It will get even louder when you are applying throttle during a turn. If you hear this noise, you can be certain that you’re most likely dealing with a bad constant velocity joint. 

As far as what the noise indicates, it’s wear. A lack of lubricant or excessive usage can cause this clicking noise. To make it indeed the problem, you can accelerate while the steering is turned fully in either direction.

Vibration

While it’s not as prone as the symptoms mentioned earlier, a bad CV axle could also lead to vibration. This will only occur if the CV axle is almost completely worn out. The reason for the vibration is the lack of balance. As with most parts of the drivetrain, rotational components need to be balanced. When this is no longer the case, the axle will produce vibrations which will be felt at higher speeds. Keep in mind, if you are experiencing this symptom it’s a good idea to get it fixed soon as it makes the car unsafe to drive.

Bumpy Ride

Another uncommon symptom of a bad CV axle is a bumpy ride. This will only occur if the CV axle has reached the end of its life. The reason this affects your ride quality is that the CV axle is integrated with the steering and suspension systems. Something like a completely failed CV axle will negatively affect the suspension system which in turn will result in a bumpy ride.

What Causes a Bad CV Axle?

A CV axle has a service life, it isn’t designed to last for the lifetime of the vehicle. However, aside from regular use, CV axle failure can be caused by issues related to the rubber boot. These boots can fail by developing cracks or tears due to several reasons. 

While they are made to take on harsh conditions, prolonged exposure to the elements can cause them to fail. Excessive heat, dirt, and debris are among the top causes of boot failure. Once the boot fails, it’s only a matter of time before you’ll have a bad CV axle.

How to Prevent a Bad CV Axle?

The best way to prevent a bad CV axle is by inspecting it from time to time. We recommend checking the rubber boots every time you perform an oil change. This will help you keep a track of things and stop a potentially bad CV axle. 

Many CV axles are designed in a way to allow for the rubber boots to be replaced. When performing an axle boot replacement, you need to repack it with fresh grease. However, this can only be done if the boot failure is caught early. 

Is Your CV Axle Already Bad? We’ve Got You Covered

Most modern CV axles don’t offer the option to be repaired. They are designed to serve for a specified amount of time and will likely need to be replaced at some point. If that’s the case, you have no other option than to get a new CV axle. 
Similarly, if you were late in catching a bad CV axle, you are better off getting a fresh replacement. Here at Newparts.com, we offer has some of the highest quality CV axles at the best prices. Have a look at our catalog and find one that perfectly matches your vehicle.