Has your car started making a clicking noise from one of its front wheels when you take a turn? It might mean you have a bad CV axle. In this article, you’ll learn about some of the most common bad CV axle symptoms and what you need to do when you start hearing the telltale clicking noise.
What is a CV Axle?
First things first… what is a CV axle?
A CV axle is the part of your car that transfers the power made by your engine to the wheels.
In other words, CV axles are vital parts in making your car get you from point A to point B.
No axle, no go.
CV axles are generally used in front- and all-wheel drive vehicles.
What does CV stand for?
The CV in CV axle stands for constant velocity.
This basically means your axel can move up and down; left and right; and all around without losing any power (in other words, maintain constant velocity!)
In a solid axle arrangement, you can lose velocity because of some sort of impossible-to-understand physics rules you probably don’t care about. So I won’t bore you with them.
What matters is this – CV axles are basically flexible drive shafts. They can continuously spin your wheels while taking turns and moving up and down as you go over bumps.
Well, to me at least. I find the engineering behind these axles absolutely fascinating.
If you’re a big car geek like me and are curious about how a CV axle works, check out this video from the guy at Speedkar99. In it, he disassembles a CV axle and shows you how it all works. He also uses his brother’s underwear to clean grease off the axle… which is awesome.
Bad CV Axle Symptoms
The main bad CV symptoms you need to be aware of are a leaky axle, a clicking noise when turning, and your car shaking at high speeds.
These three symptoms are listed in order of progression of a bad cv axle. The sooner you catch these symptoms, the better off you (and your wallet!) will be.
It’s important to understand each of these bad CV axle symptoms so you can hopefully fix the problem before it gets worse (and more expensive to fix).
A leaky axle is the first indication you have a bad cv axle.
Unfortunately, a leaky axle can be hard to detect because CV axles use grease as lubrication instead of oil.
CV axle grease isn’t runny and therefore won’t drip and leave noticeable puddles under your car like an oil or antifreeze leak does.
Plus, your axle is always spinning when you move…. So if you have a leaky axle, chances are the grease is going to be splattered all over the place under your car.
It’s actually fairly easy to spot if you get underneath your car and look at the area around the backside of your wheels. You’ll see CV axle grease splattered all over the place.
A good mechanic (or you if you’re a DIY’er) should spot a leaky axle during an oil change.
You also might be able to see it on the outside of your car wheels. It depends on the design of your wheels. If they are very open, chances are some of the grease will sling out onto the outer sides of the wheel. This happened on my Audi allroad. My wheels are an open “five star” pattern and when I had a leaky axle, I could see grease marks on the outward-facing part of my wheel.
CV Boot Replacement
A leaky axle doesn’t necessarily mean your CV axle is bad. There’s a good chance that all you need to perform is a CV boot replacement.
A CV axle has rubber CV boots on each end of it. These CV boots cover the CV joints on both ends of the axle and basically encase the CV joints in lubricating grease.
These rubber CV boots are very durable and will last a long time. But they live hard lives!
Think about it for a second…. They are inches from the road surface and often traveling at high speeds. And they are exposed to all kinds of weather, debris, and ice melt chemicals (for those of us who live in climates with harsh winters).
And don’t forget… inside your CV boots the CV joints are constantly rotating and moving.
No matter how durable they are, eventually they are going to wear out.
A worn out CV boot will rip or tear, and the internal grease escapes. This creates two problems: loss of lubrication and exposure to the elements.
Loss of lubrication
Escaping grease means less lubrication for your CV joints. Remember, your CV joints are constantly spinning and moving in and out; up and down; and left and right. These parts work hard!
So when they lose the grease keeping them lubricated, moving metal on metal will create friction and eventually damage the CV joints.
Exposure to elements
A tear in a CV boot allows water and road debris to get inside of your CV boots. This will eventually degrade the grease and reduce lubrication.
Remember, you’re already losing grease because of the tear. When you introduce contaminants, you’re accelerating the degradation of what little grease is left.
And once again loss of lubrication means your CV joints will create friction and wear out.
All that said, if you discover a leaky axle and a torn CV boot, you should get it fixed ASAP!
Because a CV boot replacement is way cheaper than a complete CV axle replacement.
To give you some perspective, I had to replace the entire CV axle on the driver side of my allroad and the part cost me about $375. About a year later, I had to replace the CV boot on the passenger side and the part cost me only $20!
Quick side note, I got my replacement Audi CV axle from GermanAutoParts.com. It was an OEM axle made by GKN. My local Audi dealership quoted me about $1,200 for the same part. I saved over $800 by shopping at GermanAutoParts.com. Wowza!
I’ll embarrassingly admit that I knew I had a torn boot on my driver’s side, but I waited too long to replace it and ended up causing damage to the CV joint… so I had to replace entire CV axle. Ugh!
Bottom line…. the longer you wait to fix a torn CV boot, the more likely you are to cause damage to your CV joints and CV axle. Don’t be stupid like me. Get it fixed.
Clicking Noise When Turning
The next thing on the list of bad CV axle symptoms is a clicking noise when turning.
This bad CV axle symptom can take some time to identify because it only happens under certain conditions.
It may only click when you take a turn under moderate acceleration. The moment your car straightens out, the sound goes away.
“Must have just been a stick I ran over,” you think to yourself.
Depending on which axle is bad, the noise can come from either the right or the left side. It’s uncommon for both axles to break at the same time, but it could happen. Lucky you!
Remember, I said the clicking noise when turning happens under acceleration. This sound generally only happens when you are giving the car some gas.
You’ll hear it when you are turning into traffic from a stop. Or if you’re driving through a long curve that requires you to accelerate. If you coast through a turn, you’re probably not going to hear the clicking noise.
It may take you some time to notice the clicking noise when turning because it only happens under these certain conditions.
If you ignore the clicking noise for too long, itwill likely get louder and more persistent. You’ll hear it every time you accelerate… even when going straight. And you’ll eventually end up experiencing the final bad CV axle symptom – your car shaking at high speeds.
Car shaking at high speeds
This is the last bad CV axle symptom you will experience before having complete axle failure.
If you’ve ignored the leaky axle and the clicking noise when turning and now your car is shaking, you need to get your car off the road and fixed. This is an unsafe condition that can cause you to lose control of your car. Not good.
However, your car shaking at high speeds can be a number of different possible issues. But for the sake of simplicity and keeping with the topic of bad CV axle symptoms, we’ll assume in this article that your car shaking at high speeds is because you have a bad CV axle.
Regardless of the source of the problem, if your car is shaking at high speeds, get your car checked out ASAP.
Bad CV axle symptoms generally progress in the order you’ve just learned about in this article. It starts with a leaky axle, then turns into a clicking noise when turning, and finally you’ll experience your car shaking at high speeds. As soon as you notice any of these bad CV axle symptoms, you should have them fixed as soon as you can.
About the Author
Hi I’m Kevin and I’m a car guy. I first got the bug as a kid when I helped my dad rebuild the motor in his 1969 Mustang. I shadowed him for countless hours doing all kinds of hands-on work in the garage. As I got older, I started working on my own cars – from new transmissions to stereos to fine detailing. I started this website to share some of the things I’ve learned over the years.
Header image courtesy of GermanAutoParts.com