Not every driver knows what a CV axle is until they find out that the trouble they're having with their vehicle is caused by a bad CV axle. if you're having trouble with yours it's good to know exactly what it does and what it's going to cost you to get it replaced. To start with, the CV part of the name CV axle stands for constant velocity. Some people also call it a half shaft. In a front-wheel drive vehicle this is what allows the power that is created by your engine to be converted into the motion that makes your wheels move. If there's a problem with your CV axle and you need to get it replaced, you can expect to be paying somewhere in the neighbourhood of $900 to $1,250 to get the job done.
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The make and model of your vehicle is obviously going to have an impact on just how much you need to pay for a job done as higher-end and rare vehicles typically have greater repair costs associated with them.
What is the Difference Between a CV Axle and a CV Joint?
Odds are when you research a CV axle, you're going to come up with the term CV joint quite a bit as well. Many times, if you look for a CV axle online, you'll actually just get CV joints as your results. That would make you wonder if they are the same thing and if not what's the difference between the two?
To start with a CV axle and CV joint are not the same thing. The CV joints are actually at the end of the CV axle. So, on one CV axle you have two CV joints. There is an inner joint and an outer joint. The inside of a CV joint has lubrication in it, and it's covered in what they call a CV boot, which is like a rubber casing to keep that lubrication in place.
A CV axle is called constant velocity because no matter which way you turn, because of the inner and outer joints, it's going to maintain a constant velocity. The CV axle transmits power from the drive shaft, or drive axle if you prefer and keeps it at that constant velocity between the inner CV joint in the outer CV joint in a way that older U-joints can't manage. Basically the CV joints are transmitting the torque from the transmission to the wheels and keeping them at a constant speed while at the same time adjusting for the up-and-down motion of the car as it goes over uneven terrain. Inside those rubber boots that hold all the lubrication you've likely got either a ball type joint or a tripod type joint. CV joints can be made either way it really just depends on your car.
What Are the Signs of a Bad CV Axle?
If you're not sure if it's your CV axle giving you trouble or not in your car there are a handful of signs that you can be on the lookout for it to let you know that you're having a problem with your half shaft. These are the most common signs and symptoms of a bad CV axle that you need to be on the lookout for.
Vibrations: When your CV axle is failing on you or has been damaged in some way you're going to have some increased vibrations while you're driving. Obviously, there are a number of different reasons why your car is going to vibrate while you're driving, not to mention the fact that it vibrates normally even when it's working absolutely within operational parameters. When you do have a problem with your CV axle however the vibrations are going to be very noticeable and will almost make your car feel like it's bouncing when you get up to speed. This is especially true if you are on an uneven road or going over bumps and potholes.
This kind of vibration can get to the point that it becomes difficult for you to actually maintain proper control of your vehicle. You'll notice it through the steering wheel and it's going to affect your handling and the comfort of the ride when you're driving. If the CV axle is bad enough that it's causing this excessive level of vibration, then it's definitely going to need to be replaced.
Noises: When your CV axle is damaged you may notice a distinct knocking or clunking sound while you're driving. This won't be intermittent; in fact, it will likely be more of a rhythmic sound that keeps pace with the speed of your vehicle. Pay special attention if the sound becomes louder when you reverse as that is almost definitely a sign that it's your CV axle causing you difficulties. There are some other potential causes for this kind of noise coming from the front end of your vehicle, but definitely give your CV axle a look just in case if this is what you were experiencing.
There's also the potential that you are going to experience a distinct clicking noise but only when you turn. This will be a very loud sound, and hard to mistake for anything else. It's more of a clicking, popping noise and there is almost nothing else in a car that will make a similar sound. If you haven't heard it before, you'll definitely know it when you do. It's caused by a loose joint at the end of the CV axle.
You may also notice the clicking noise when you're accelerating the vehicle, though it is more common when you are turning. It's possible that as a result of the wear that causes this popping and clicking sound you'll also have a harder time steering, especially when you're going around bends or taking corners.
Grease on the Tires: As we mentioned before the inside of the CV joints at the end of your CV axle are filled with a lubricating grease. If that rubber boot that keeps it all sealed in place breaks down, then all that grease will come leaking out and it's going to coat the insides of your tires. If you take a look at your tires and see that there's grease only on the inside edge of them, then that's a clear indication that either the CV axle has been damaged or at least the CV joints have been compromised.
Can You Drive on a Bad CV Axle?
Obviously, it's never a good idea to try to operate your vehicle with damaged parts. That said, there is always a limited lifespan that you'll be able to enjoy when you are driving a vehicle with various parts that aren't working properly. For instance, when you know your oil needs to be changed, you do have some wiggle room before you need to head into a mechanic to get it replaced, it's not like your car is going to shut down right away just because it hasn't been done.
Likewise, if your CV axle does need to be fixed, you should have at least enough time to get you into the mechanic to get the problem fixed. If you're experiencing the vibration and the sounds that we've mentioned, you're probably safe to continue driving for upwards of a couple of months before it's going to be so bad that you can't drive any longer. This is really at the outside realm of tolerance, however. You never want to push your vehicle when you know something is wrong with it, and if you can afford the time and money to go in to get your CV axle repaired sooner then you absolutely should do so. The longer you put this off, the worse the axle is going to get. This can end up causing damage to your wheels, your brakes, even potentially your transmission as well. Of course, if it gets so bad that the axle breaks while you're actually driving your car it could lead to a serious accident that could harm you and others on the road as well.
Even if your CV axle doesn't break on you, when it fails completely it will simply stop moving. That means that the movements created by your engine will not be able to transmit to the actual wheels of your vehicle so your car will just stop moving if it happens evenly across both axles. If just one axle fails, then that one tire is going to die on you, and you could potentially have some difficulty controlling your vehicle or it may just stop on you completely.
If you happen to live in a Northern climate and you're in wintry conditions with slippery and icy roads, then you'd do well to ensure you get this taken care of sooner rather than later. As we mentioned, one of the potential symptoms of a bad CV axle is that you're going to have difficulty handling your vehicle due to the vibrations as well as when you try to turn corners. This will be exacerbated by poor weather conditions so it's in your best interest to make sure you get the job done as soon as you can.
How Long Does It Take to Replace a CV Axle?
When you take your vehicle into a mechanic to get the CV axle repaired you can expect that you're going to be leaving it there for about an hour or two just to get the job done. That's for one axle. If you're getting two axles done, then obviously you're going to be looking at twice that amount of time. Of course, the mechanic may have other work they need to get done, so you could be expecting that it's going to take the better part of the afternoon before you'll see your car again.
Can You Replace Just One CV Axle?
You have a CV axle on either side of your car, and two CV joints on each end of those axles. if one of your axles becomes damaged and requires a replacement, you may be tempted to simply do that one axle and not the other one. The problem here is that you'll have inconsistent reliability if you replace just one axle but not the other one. Theoretically your CV axles should have the exact same lifespan as one another. However, if one is damaged in an accident then you should still replace the other one even if it's fine just so that your new axles can effectively reset the clock together and you'll know that they have relatively the same lifespan going forward.
You don't have to replace both axles at the same time, you just have to be aware that the one you don't replace is going to wear out much sooner than the one that you did replace so again, further down the road, you're going to have to replace one axle as opposed to both axles. It's just more of a convenience thing that you get them both replaced at the same time so you can expect that they will be consistent in their performance going forward.
The Bottom Line
The CV axle in your vehicle does an important job even though most drivers are probably not aware of where it's located or what it does. When you're noticing any of the symptoms that we've mentioned related to a bad CV axle the best thing you can do is heading to a mechanic as soon as you can get it checked out. You don't want to risk your own safety or the safety of others on a bad CV axle that's going to fail on you in the middle of driving sometime.
Remember it can be easy to misinterpret the symptoms of a bad CV axle with a host of other issues that you could be facing in your vehicle. For that reason alone, it's best to go in and get a mechanic to properly diagnose any issues you were experiencing because it could be a much more serious problem then you at first believe it is simply because it's so easy to make mistakes.