What is the Function of Car Axle? | How much does it cost to replace a Car Axle?

Vehicles are most commonly used all over the world. The vehicle consists of multiple parts, and the axle is one of them. The vehicle axle ensures efficient driving. It helps to turn the vehicle wheels. This article mainly explains the symptoms of a bad car axle symptoms, its replacement cost, and its types.

What Is a Car Axle?

An axle or axletree works as a central axis that turns the car gear or wheel. The axle is a mechanical device that makes a connection between the vehicle’s tires and wheels.


The main function of the axle is to receive power from the engine through a power transmission system and deliver this power to the vehicle wheels to turn them.

At one end of the axle, there is a long bolt attached to the wheel with a lug nut, and the other end is connected to the car’s power transmission system, which turns the wheels after receiving power from the engine.

In the case of a vehicle with wheels, the axle is connected to the wheel and rotates the wheels. In another case, the axle can be attached to the vehicle, and the wheels rotate around it. In the first case, the bushing or the bearing is installed at the attachment point where the axle provides support. In the second case, the bushing or bearing installed in the wheel center hole, which allows the gears or wheels to reciprocate about the axles.

Design of Axle

The car axle design is derived from the chariots employed in ancient Greece. When a horse forced a chariot, this axle turned the wheel. The axles also tolerated the traveler’s cabin weight. With the passage of time, this model was used in horses and carriages and eventually in vehicles.

design of car axle

A front-wheel-drive vehicle contains an axle that links the front wheel to the engine and drivetrain. This design is exceptional for front-wheel-drive cars. The front-wheel drive links the transmission and engine directly to the differential gears on the front wheel axle.

The rear-wheel drive contains a standard axle that links the rear gear to the driveshaft and transmission. When the drive shaft rotates, the rear gear rotates the wheels of the car. It uses gear drive technology to turn the wheel around the axle with a precise gear ratio.

A Four-by-four car contains gears on the rear and front axles. This causes the front and rear wheels to rotate according to the engine speed. This complicated construction increases the installation and repair costs of the four-by-four axle.

Types of Axles

The car axle has the following three major types:

  • Rear axle
  • Front axle
  • Stub axle
Types of Axles

1) Rear Axle

These types of axles have a responsibility to deliver power to the drive wheel. It has two halves called the half shafts that link to the differential. In maximum conditions, the rear axle rotates with the wheels of the vehicles.

2) Front Axles

As the name of this axle represents that it is located at the front of the car. It helps to turn the vehicle and communicate with the car shocks while driving on bumpy roads.

The front axle has the following four major components:  

  1. Stub axle
  2. Tie rod
  3. Swivel pin
  4. Beam

This axle should be as strong as possible. Therefore, nickel steel or carbon steel is used for its construction.

Types Of Front Axle

The front axles have the following two types:

  1. Dead Front Axle: These are static axles and don’t spin with the rotation of the wheels. 
  2. Live Front Axle: These axles also supply steering system power to the front wheel.

3) Stub Axle

It is to the front wheels of the car, and the kingpin connects it with the front axle.

Types Of Stub Axle

The stub axles have the following major three types:

  1. Elliot: It has a cotter, a yoke, and a kingpin that connects with the front axle.
  2. Lamoine: It has an L-shaped spindle instead of a yoke-type hinge.
  3. Reverse Elliot: It has a totally reverse arrangement to the standard Elliot stub axle.
  4. Reverse Lamoine: This axle has the opposite layout of a standard Lamoine stub axle.

Symptoms of a Bad Car Axle

When your car axle goes bad, it produces one or more of the below-given symptoms:

  1. Vibration while driving
  2. Brake pad misalignment
  3. Car won’t budge
  4. Knocking sound
  5. Grease on the edge or inside the tires
  6. Leaking
  7. Difficult steering
  8. ABS light

1) Vibration While Driving

Car Vibration

Car vibration during driving is one of the most common symptoms of a bad axle. However, your car may also vibrate because of many other reasons such as a bad carburetor, damaged struts, a bad steering system, and many others.

However, if you notice extreme vibration which increases with speed, or an unusual “bouncy” feeling in your driving, this may be due to a faulty constant velocity (CV) axis. In such a condition, you must stop your vehicle, inspect it, and fix the source of vibration. If you cannot find the problem, contact a technician and ask him to fix it.  

2) Brake Pad Misalignment

Brake Pad, symptoms of bad car axle

If the bent axle starts to deteriorate, your car’s braking system will start to generate problems. In such a case, your car brake pads start moving, and they will be misaligned with the rotor and wheels. In this case, the car may skid or stop.

If you do not fix or replace your axles on time, your car brakes will ultimately fail to work.

3) Car Won’t Budge

The most common symptom of a damaged axle is the inability of the vehicle’s tires to spin. The car starts normally. When switched on, the engine produces sound as normal. No electrical issues, no dash warning lights, or weird clicking sound.

Why is this happening? This usually occurs due to a bent CV joint that eventually breaks like a Slim Jim. In such a situation, drive your vehicle to a nearby repair facility to inspect and repair CV joint damage.

4) Knocking Sound

As you notice muffled or knocking sounds, immediately find the reason for this sound. There are many reasons due to why your vehicle can suddenly produce this sound. A damaged CV axle is also a common reason for a knocking sound.

In some conditions, the knocking sound increases as you reverse your car, and you can hear it more clearly. In such a situation, you must immediately call a specialist to fix it. So that you can save yourself from more severe results.

Read More: Bad Knock Sensor Symptoms and Causes

5) Grease on the edge or inside the tires

The constant speed axle’s joints contain a protective greased cover to prevent lubrication leakage during the rotation of the axle. If the protective cover leaks, there will not be enough lubrication to decrease the axle’s wear and tear while rotating.

This insufficient lubrication can cause CV joint failure. Therefore, as you observe grease on the inner side or edges of the wheels, immediately fix it; otherwise, it can lead to a costly repair.

6) Leaking

The brake seal on a 4WD or AWD vehicle’s driveshaft might shift, leading to minor oil leakage. You can observe this issue while examining the brake drum.

Additionally, the CV joints have the potential to release grease, although this is less common. When the grease starts to leak, the joints may accumulate contaminants and experience rapid deterioration.

7) Difficult Steering

Steering Wheel Hard to Turn

When your axle goes bad, it may badly affect your steering ability. You may observe that the steering feels stiff or that the vehicle doesn’t respond according to the requirements.

Read More: Why Is Your Steering Wheel Hard To Turn?

8) ABS Light

ABS light, signs of bad cv joint

In the case of modern vehicle models, when the axle becomes faulty, it may impact the performance of the Anti-lock Braking System (ABS). When the engine control module (ECM) of the vehicle monitors an issue with the ABS system, it triggers the ABS light.

Causes of a Bad Axle

A proper working axle is very important for the efficient performance of your car. There are various factors that may cause a car axle to go bad. The following are the most common causes of a faulty car axle:

  • Constant Velocity Joint: The constant velocity joint connects the driveshaft of your vehicle to the transmission system. If the torque is transmitted there, it will be easily damaged.
  • Speed ​​Bumps and ​​Humps: The speed bumps and humps may slow down the vehicle at certain points while driving. If the car height is not sufficient, then the speed humps and bumps may directly hit the axle, and your car axle may be damaged.
  • Rust: Rust and worn metal can seriously affect shaft strength and durability. Therefore, rust is one of the major causes of axle damage.
  • Collisions: A direct collision from the front or rear of your car may lead the axle damage. However, if the collision is not direct, your axle can still be damaged because of the exerted pressure.

How to Choose the Right Axle Ratio for Your Pickup Truck

  1. Stickers on the car windows represent the fuel consumption data for the standard axle ratios. If you want your vehicle to consume a low amount of fuel, choose a vehicle that contains a custom axle ratio.
  2. Maximum suppliers mention high axle ratios as short gear and low axle ratios as high gear. The former can pull heavier loads than usual, while the latter has better fuel economy.
  3. A comparison of the available axle ratios from different vehicle manufacturers is not possible. Different tire sizes influence the running of the vehicle and the final design

How much does it cost to repair an axle on a car?  

The car axle is very expensive to fix or repair. The repairing cost of the axle varies according to your vehicle model, labor costs, type of the axle, and severity level of the damage.

The fixing cost of a rear axle is between $650 to $1100, while the repairing cost of the front axle is between $450 and $800.

How To Replace A CV Axle In Your Car

FAQ Section

What is the function of the axle?

The main function of the axle is to receive power from the engine through a power transmission system and deliver this power to the vehicle wheels to turn them.

How much does to replace the axle on a car?

The replacement cost of a car axle depends on various factors such as labor cost, type of the car, type of the axle, and brand of the axle shaft. The average replacement cost of the car axle shaft is from $750 to $1,200.  

Can a bad axle make your car shake?

Yes, a faulty axle causes the suspension system to vibrate or shake frequently and violently. If you do not fix the issue early, then the shaking issue may become violent as you reach high speeds. Therefore, it is always safe to fix shaft-related problems in time.

How Many Axles Does a Car Have?

The number of axles in a vehicle varies according to the car type. The axles are mainly used to turn the wheels. Most cars contain two axles. Larger vehicles, carrying more passengers and containing more wheels, may have more than two axles.

Determining the number of axles in a car is easy. If you want to determine the number of axles in a vehicle, just look from the side and count the pairs of tires. Most cars have two sets of tires (one front and one back) or a total of four tires. Only two axles are enough to turn the two sets of tires.

What noise does a bad car axle produce?

If the CV joint on the axle becomes faulty, it starts to produce a clicking, clunking, or popping noise. This noise becomes clear when you turn your car.

Can a bad CV joint affect the transmission?

Yes, a bad CV joint can badly affect your transmission. It can impact the transmission performance by inducing binding in the driveshaft. This situation can arise because of a misaligned or damaged CV joint. Should this occur, the driveshaft is at risk of fracturing, subsequently leading to transmission failure.

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