The CV or Constant Velocity joint is a unit in all-wheel drive cars which enables even transmission of power via various angles without causing too much friction. Though the CV joint is mainly in all-wheel drive cars, it can also be found in some rear-wheel and most front-wheel drive vehicles.
Like any other part of your vehicle, the CV joint can malfunction. One of the most common indications of a CV joint malfunction is producing noise when driving straight.
Your car’s CV joints may become noisy if they wear out after using it for a long time without replacement. Lack of lubrication may also cause your CV joint to be loud, especially when you start accelerating. Other causes of CV joint noise include damaged boot clamps or faulty CV boots.
For your vehicle to function perfectly and give you a smooth ride, you must ensure that all components are in good condition. If your car’s CV joint is malfunctioning and you wonder what to do, this post shall be valuable. You shall learn the reasons and solutions for a noisy CV joint and how to care for it.
What is a CV Joint?
Before we address the elephant in the room, it is imperative that you understand what CV joints are and their functions in your vehicle. Constant velocity joints, or CV axle, are categorized into ball-type and tripod-type joints. The ball-type joint is placed on the outer CV joint, while the tripod-type is placed on the inner joint.
The inner and outer CV joints are found on both sides of the drive shaft to connect the wheels to the transmission and axles. If your car is an all-wheel drive, it can have up to four CV shafts, but rear or front-wheel-drive cars have two CV shafts.
Heavy trucks and all-wheel drive cars have the Cardinal CV joints, while the front-wheel-drive cars come with Rzeppa CV joints.
The CV joints hold the drive shaft in position and supply the drive wheels with torque produced by the transmission. If the car is four-wheel drive, the torque is provided to all the wheels, but in two-wheel vehicles, the CV joints transmit torque to either front or rear wheels, depending on the drive type.
Besides transmitting torque, the CV joints accommodate your car’s suspension to ensure that your vehicle’s body is independent of the wheels.
Therefore, the car’s body remains still when you hit potholes or uneven terrain, giving you a comfortable ride and increasing your vehicle’s maneuverability.
The CV joints ensure that your wheels turn when you press the acceleration pedal. Therefore, it will affect your car’s functionality and handling if it malfunctions. Ensure that your car’s CV joints are in good condition and are regularly checked by repair mechanics.
What Causes CV Joints Malfunctioning?
The CV joints are made to last long without regular checkups and maintenance. The CV joints have a protective CV boot made of rubber or plastic, containing a special grease that lubricates the joints. One of the leading causes of CV joints failure is the breakage of this protective CV joint boot.
After the CV joint boot gets damaged or breaks, it causes the lubricant to spill and dirt to enter the CV joints. When moisture, debris, and other impurities enter the inside of the CV joints, it causes corrosion and damage. The joints will also fail due to a lack of lubrication since the grease spilled off when the CV boot cracked.
One of the most evident indications of malfunctioning CV joints is clicking sounds when your car turns and noise when accelerating and driving straight. Now that you know what CV joints are and their functions, let’s address the big issue, “CV joints noise when driving straight.”
CV Joint Noise When Driving Straight: Causes
When CV joints start getting damaged, they malfunction and produce noise when you are turning the vehicle or driving straight. The noise indicates a problem with the joints but does not necessarily mean that they are damaged beyond repair.
Before you repair the CV joints or take them to a repair mechanic, it is essential to understand the causes of this noise. Let’s look at the grounds of a noisy CV joint:
1. Damaged CV Boots
The CV boots are protective covers that house the CV joint and its lubrication. Since the joints always move whenever your car is in motion, the grease plays an essential function in lubricating the moving parts and reducing friction. With reduced friction, the joints will move smoothly and therefore last longer.
Besides housing the joints and grease, the CV also prevents dust and debris from entering the inner parts of the CV joints. The CV joints can attract a lot of dirt from the roads if the CV boot is absent since it is positioned at the car’s bottom.
Since CV boots are made from rubber or plastic and positioned at the bottom of the car, they can get damaged easily, especially when driving off the road.
Sharp objects or rocks may damage the CV boot or rip it off completely. When this happens, the lubricant drips down, and impurities like sand and dirt start accumulating inside the CV joints.
As the dirt accumulates, it erodes the joints and causes the CV joints to tear and wear. Additionally, the CV joints will start generating a lot of friction due to the absence of a lubricant.
The friction and corrosion cause the CV joints to produce noise when driving straight, accelerating, and making turns.
Your CV joints will become worn out as the vehicle covers more miles, just like any other car part. Though the CV joints are very durable, they will wear out with time and require replacement.
Once you hear noise coming from your CV joints, it is great to have an expert check it and determine if it needs replacement due to old age.
When CV joints are new, they fit perfectly and run smoothly without being noisy. However, as you keep using your car more frequently, the metal parts start wearing out and make the joints and components not fit tightly.
As they loosen, the parts start moving around and grinding against each other, which causes clunking noise.
3. Faulty CV Boot Clamps
The CV boot clamps seal and keep the CV boot in position and thus preventing it from falling. The clamps should always be tightened to function correctly and protect the CV boot.
The clamps may start loosening as you drive the vehicle and hit bumps or potholes. The CV boot clamps may also get corrosion and damage, making the boot loosen.
When the CV boot becomes loose, it will allow dirt and impurities to enter the joints, causing the inner V joints to clunk.
Additionally, it will lead to spillage of the lubricant, which will make the joints to cause friction and produce noise.
4. Lack of a Lubricant
Moving parts in a vehicle or other machines require lubrication to ensure the components run smoothly and reduce friction. If there is friction between moving parts, the parts will produce squeaking sounds after the parts start moving.
If your car’s CV joints lack lubrication, it increases friction and prevents the free rotation of the CV axle. When you start accelerating and the axle starts rotating, the friction will increase and cause the joints to produce squeaking sounds. The noise becomes louder as you accelerate, and the axle turns faster.
CV joints use grease as the lubricant to reduce friction. When grease is lacking, the metal parts start rubbing against each other and produce noise.
The lack of grease in the CV joints may be caused by a damaged CV boot or faulty boot clamps. Whenever you repair or replace CV joints, you should add grease to prevent friction and noise.
Signs of Faulty CV Joints
Besides the CV joint making noise when driving straight or turning, other signs can indicate that your CV joints are faulty. These include:
- Grease stains
- Cracked CV boot
1. Grease Stains
If you drive a front-wheel-drive car, the CV joint is usually located near the front wheels, while rear-wheel-drive cars have their CV joints near the back wheels. When the CV joint is damaged, the grease inside the CV boots starts leaking. Since grease has a higher density than other car fluids such as coolant or transmission oil, it does not form puddles.
Leaked grease looks like a thick black fluid and will stain your rim and wheel. If your car is rear-wheel drive, the stains from the CV joints will form around the back edges and wheels. For front-wheel drive vehicles, grease stains around the front rims and wheels may indicate a faulty CV joint.
You may also note grease stains around your home garage, driveway, or parking lot. However, a faulty CV joint is not the only cause of grease stains in a vehicle.
If your differential is damaged, it may lead to grease leakage and stains. Therefore, have a professional diagnose your car to determine the root cause of the leakage.
2. Cracked CV Boot
When inspecting your car, you might note that the protective CV boot is damaged or have cracks. When the boot is cracked, the CV boot clamps might be damaged, loose, or have corrosion and therefore cannot hold the CV boot perfectly.
If the CV is broken, it might have exposed the CV joints to dirt or caused the grease to spill. The CV joints get damaged due to corrosion and friction when this happens.
Call a repair mechanic immediately if you realize that the CV boot is cracked or broken. Before driving again, ensure the cracked CV boot is replaced, joints cleaned, and grease added.
The CV axle is one of the leading car parts determining your car’s comfortability, maneuverability, and handling. When the CV joints malfunction, they cannot keep the cars balanced while supplying torque to the wheels. Therefore, it will cause the vehicle to vibrate and shake when you start driving.
The vigorous shaking and vibrations can be dangerous since it makes it challenging for you to control the vehicle and maintain your lane. If not rectified, it can easily cause an accident. However, vibrations can also be caused by unbalanced wheels or faulty wheel bearing.
If your car is shaking/vibrating and you can hear the CV joints making noise while driving straight, you can rule out that the CV joint is faulty. If there are no other signs besides vibrations, ask for help from a professional mechanic to determine why the car is vibrating.
CV Joint Noise When Driving Straight: Solutions
After ruling out that the CV joints of your car are damaged, you need to take immediate action. If the CV joints are not damaged, but the CV boot is damaged, you can replace it at home or pay a professional mechanic to do it for you.
1. Replacing the CV Joint Professionally
If your CV joint is damaged, you will have to replace the CV joint. Your car’s brand, model, and age will determine the replacement cost. You may also incur more charges if the faulty CV joints have caused damage to other car parts.
If your car is insured or has a warranty on CV joints, you might save on the replacement cost. For instance, Mercedes Benz cars come with a lifetime warranty covering CV joints. Therefore, you will not incur replacement costs when the CV joint in your Mercedes Benz requires repair or replacement.
A new CV joint may require an investment of between $95 and $210, depending on your car. Hiring a professional mechanic may range from $165 to $800, depending on the time to repair the whole unit.
Another factor that affects the CV joint replacement cost is the type of axle you are replacing. If you are replacing a double axis, the price can be twice as higher as replacing a single axle.
2. Replacing the CV Joints Yourself
If you have some mechanical knowledge and do not want to spend a lot of money hiring a mechanic to replace the CV joints, you can do it yourself at home. You will need to purchase a CV joint kit which consists of a CV joint, grease tube, CV boot, and two boot clips. In some cases, it might also have nuts.
You will also need tools such as a car jack, axle nut, and torque wrench. Before working on the vehicle, switch it off and engage the handbrake to prevent any movement. Once done, follow these steps to replace the CV joints:
- Jack your vehicle up: Remove the axle nuts and loosen lug nuts before raising your vehicle. Since the lug nuts are different from one car to another, you need to have different socket sizes to get the right one for your car. Lift your vehicle using a jack or car lift but ensure you check the car’s manual to get the correct position.
- Remove the wheels: Remove the lug nuts to take off the wheels. Free the hub assembly by levering the lower suspension using a socket. Ensure you take care to prevent damaging the ball joint dust cover.
- Release the CV joint: Pull out the driveshaft by pulling the CV joints from the hub assembly. To avoid the rotation of the hub assembly, you should have someone press the brake pedal while removing the nut on the driveshaft.
- Release the CV joint clamp: Remove the clamps that hold the CV boot, then remove the joints. You can make this process easier by using a CV joint extraction tool.
- Fit the new CV joint: Once you have removed the damaged CV joints, clean and lubricate the necessary parts and fit them back. Ensure that you tighten all bolts and nuts before lowering the vehicle.
Fixing the CV joints yourself can be challenging if you don’t have some mechanical experience or assistance. Therefore, it is best to leave this to experts as you might damage the car, which may result in extra costs. Now that you know how to fix your faulty CV let’s look at some of the questions you might be having regarding faulty CV joints.
How Long Can You Drive on a Faulty CV Axle?
Depending on your car model and the cause of the damaged CV axle, your car can go for up to one year with a faulty CV axle. However, this will also depend on your region’s climatic conditions.
If you are driving in drier areas, you can drive the car for up to 6 months with a faulty CV joint. On the other hand, people living in wet areas where it’s rainy and snowy should replace a broken CV axle as soon as they realize it has a problem.
Regardless of your car’s model or region’s climatic condition, it is advisable to have your vehicle checked immediately, if you notice a problem.
If the mechanic rules out that the CV is damaged, have it replaced before driving the car. Driving a vehicle with a faulty CV axle may lead to an accident or more car damages and repair costs.
Is it Dangerous to Drive a Vehicle with a Damaged CV Axle?
The simple answer is that driving a car with faulty CV joints is dangerous. The CV axle transmits torque from the transmission to the wheels to make your car run when applying pressure on the acceleration pedal.
If the CV axle fails when you are driving, the car may stop running abruptly, even though all the other parts are functioning.
A damaged CV axle can also make the vehicle vibrate and make you unable to control the car. You might cause a severe accident in such a scenario, especially if you were speeding on a highway.
A vehicle with a damaged CV axle may also fail to turn the wheels, leading to a crash if you had already accelerated.
How to Diagnose a Bad CV Joint
You can save on paying a repair mechanic to diagnose your car for faulty CV joints by doing it yourself. Before replacing your CV joint, you need to be sure that it is damaged by carrying out a diagnosis. You can use the following methods:
1. Visual Inspection
The most straightforward way to diagnose is to check the CV boot’s condition. If you notice that the CV boot is cracked, torn, or completely damaged, the CV joints may also malfunction. You can replace the whole CV axle to solve this issue and prevent more damage.
2. Test Drive Your Car
If you note that the CV boots and clamps are not damaged after carrying out your visual inspection, you need to take your car for a test drive to determine if the CV joints are faulty. To diagnose a faulty outer CV joint:
- Engage the reverse gear, rotate the steering wheel entirely on the left side, and start reverse driving in a circle. Repeat the process by turning the steering wheel on the right side and driving reverse. The outer CV joints might be damaged if you hear the car producing snapping and clicking sounds.
You can also diagnose the inner CV joints by doing the following:
- Engage the reverse gear, then start driving in reverse while accelerating and braking. Your inner CV joints might be damaged if you hear a loud clunking noise.
After determining that your car’s CV joints are damaged, you can replace it yourself at home or have a professional mechanic do it.
CV joints are essential parts of your vehicle as they promote comfortable and smooth rides even when driving off roads. Therefore, you should ensure that they are always in perfect condition and running smoothly.
Whenever you take your car for a check-up, ensure the mechanics check if the CV joints are damaged. If they are damaged, repair/replace them immediately before driving the vehicle. Do not postpone repairs as a damaged CV axle can cause severe car damage or an accident.
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