Your CV axle is a critical part of the drivetrain that delivers power to your wheels. But if you’re dealing with bad CV axle symptoms like clicking noises or grease leaks, those wheels may not be turning for much longer.
Read on to learn what causes a CV axle to go bad, how long they last, and how to check for a bad CV axle so you can take care of the problem sooner.
Key Takeaways
- Common Symptoms of a Failing CV Axle: clicking or popping noises when turning, steering wheel vibrations during acceleration, and the presence of thick grease around the axle’s wheel well or suspension.
- Common Causes of a Failing CV Axle: Damaged boots around CV joints can leak lubricant and let in debris, causing premature wear on the joints.
- When to Have Your CV Axle Inspected: Schedule an inspection at the first sign of clicking noises or grease leaks to avoid potentially getting stranded by a failing CV axle.
What Is a CV Axle?
A CV axle, or constant velocity axle, is a key part of your vehicle’s drivetrain. It helps transfer rotational power from the transmission to the wheels. CV axles are a collection of parts, including the central axle shaft and a pair of inner and outer CV joints. These joints enable the axle to flex, rotate, and slide while continuously spinning, delivering power to the drive wheels as they bounce and turn on the road.
Most vehicles are front-wheel drive and will therefore have two CV axles—one for each front wheel receiving power from the engine. Similarly, on some rear-wheel-drive vehicles, you will find two CV axles in the rear, and most all-wheel-drive vehicles will have four CV axles.
Maintaining your CV axles and joints is an important part of maintaining your vehicle’s performance and keeping your ride safe on the road.
What Causes a CV Axle to Go Bad?
CV axles are built to last, often between 100,000 and 150,000 miles, depending on your driving conditions. If the boots protecting the CV joints stay intact, the axle can last the lifetime of the vehicle.
CV axle failure is usually caused by:
- Torn CV Boots: Protective rubber boots seal grease inside the CV joints to keep them lubricated. When boots tear or crack, the joints lose lubrication and may become contaminated with grit and debris, which can damage the inner workings.
- Aggressive Driving & Road Impact: Hard acceleration while taking sharp corners or hitting deep potholes stresses internal bearings, increasing wear within the joint.
- Normal Wear and Tear: Like any mechanical part, high-mileage CV joints and axles may simply wear down after millions of rotations over thousands of miles.
Bad CV Axle Symptoms
Clicking or Popping Noise
The most common sign of a bad CV joint is a fast clicking or noticeable popping noise, especially when accelerating through sharp turns. The clicking is typically caused by a contaminated outer CV joint whose bearings are rapidly binding and slipping against their internal housing.
Vehicles can make all kinds of worrying noises, but the next time you’re turning into a tight driveway or maneuvering into a parking spot, listen for an audible clicking noise to indicate you might be dealing with a failing CV axle.
Grease Leaking Around Wheels
The rubber boots around each CV joint act as a sealed reservoir for heavy-duty grease that keeps the joints turning smoothly. When the boot tears, the rotation of the axle shaft flings the sludge-like grease outward, splattering parts of the inner wheel, suspension parts, brake components, and even the exhaust, which can lead to a burning smell as the grease contacts hot metal.
How much grease gets flung around will depend on the severity of the leak. If enough grease lands on your brake rotors, that grease will transfer to the friction material on your pads and reduce the friction needed to slow down, impacting your ability to brake effectively. If you find grease leaking from your CV axle, don’t wait—let the pros at your local Firestone Complete Auto Care take care of the problem right away.
Vibrations That Worsen While Driving
A worn inner CV joint can cause strong side-to-side vibrations that are felt through the car’s floorboards and steering wheel. This is different from the vibrations caused by bad wheel bearings, which create a more consistent hum or shake that changes with vehicle speed. Bad CV axle vibration is felt specifically during gas pedal input, where the car may shake as you accelerate and smooth out again as you coast.
Bad CV Joint Symptoms: Inner vs. Outer CV Joints
Because the inner and outer CV joints differ in construction, the symptoms differ when one or the other fails. The outer CV joint, located closest to the wheel, handles extreme steering angles. A bad outer CV joint may create that signature clicking or popping noise heard during sharp turns.
The inner CV joint, on the other hand, is located where the axle connects to the transmission. It mostly handles the up-and-down movement of the suspension. A bad inner CV joint typically causes significant vibrations or shuddering when accelerating.
How To Check For A Bad CV Axle
There are two relatively simple ways to check for a bad CV axle:
Visual Boot Inspection
Either turn your front wheels (or whichever wheels the CV axles are located on) all the way to the side to look into the wheel well, or safely jack up your car to look from underneath. Check the rubber boots at either end of the CV axle shaft for cracks, split seams, or any visible grease leakage.
Low-Speed Test Drive
Find an open parking lot or another safe place to test drive your vehicle by turning the steering wheel fully to the left or right, then slowly accelerating in a tight circle. Do this in both directions and listen for the telltale clicking sound of a bad outer CV joint.
If you’re unsure if a bad CV axle is the cause of your vehicle’s symptoms, the technicians at Firestone Complete Auto Care can perform a more thorough inspection of your axles and drivetrain before suggesting any necessary repairs or service recommendations.
Trust Firestone Complete Auto Care to Keep Your Wheels Turning
A worn CV axle can impact how power is delivered to the wheels and, if ignored, may eventually render your vehicle immobile. Firestone Complete Auto Care offers drivetrain inspections that can help identify worn CV joints, damaged CV boots, and related steering or suspension concerns. Because CV axle symptoms can sometimes mimic wheel bearing, tire, or suspension issues, a professional inspection can help pinpoint the root cause and ensure the correct repair is made. Schedule an appointment today!
Frequently Asked Questions About CV Axles
How Long Do CV Axles Last?
Most CV joints and axles last 100,000 miles or longer, so long as the CV boots remain sealed. Catching torn rubber boots during an oil change or other service can often help prevent CV joint damage, meaning you may only have to replace the boot itself.
Can You Drive with a Bad CV Axle?
While you may be able to drive short distances with a failing CV axle, the axle damage will likely worsen the longer you drive on it, putting your safety at risk.
What Does A Bad CV Axle Sound Like?
A bad CV axle often makes a clicking or popping noise, particularly when accelerating through a turn. This sound is commonly associated with a worn outer CV joint and may become more noticeable during sharp or tight turns. A worn inner CV joint may cause clunking noises during acceleration or deceleration. If you hear unusual clicking, popping, or clunking while driving, have your vehicle inspected to determine whether the CV axle or another drivetrain component is responsible.
What Happens if a CV Axle Breaks While Driving?
Sudden axle failure on the road can cause you to lose drivetrain power to that wheel and grind your vehicle to a halt. A free-spinning axle shaft can also cause significant damage to your brakes and suspension, and leave you stranded wherever the axle break occurs. Don’t let a bad CV axle get to the breaking point—schedule an appointment with Firestone Complete Auto Care at the first sign of trouble.
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Article Development Supported & Reviewed By:
Firestone Complete Auto Care’s Technical Operations Team
The Firestone Complete Auto Care’s Technical Operations Team is composed of ASE certified technicians with over 70 years of combined experience. ASE certification represents the highest standard of technical training in the automotive industry. Guided by Firestone Complete Auto Care’s rigorous editorial standards, our team delivers timely, detailed, and practical resources drivers can trust to keep their vehicles running newer, longer.
