Car axles are rods or shafts that turn the wheels and support the weight of the vehicle. Axles use the rotational force—also known as torque—from the transmission to rotate the car's wheels.

Your vehicle is an ingenious feat of engineering composed of various moving parts. Like a puzzle, each component of your car is vital to its complete and proper function, and every piece must work together with its neighbors to keep your car moving smoothly. While your vehicle's power is generated by its internal combustion engine, that energy is transmitted to the wheels by its axles.

If you're curious about what car axles are and how they work, you’ve come to the right place. Here, we'll break it down in simple terms so you can cruise safely and with a new level of

car maintenance

knowledge.

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What are axles on a car?

Axles are essential vehicle components that carry engine power to your car's wheels and assist in steering and shock absorption. They allow your wheels to move simultaneously and at the same speed and help support the vehicle's weight.

The internal combustion engine generates the power to move your vehicle. However, the engine alone cannot turn your car's wheels.

The engine's power must first pass through the transmission, where it is converted to rotational force or driving torque. That torque is then passed to the axle shafts, which connect to your car's wheels and cause them to turn at the same speed.

How many axles does a car have?

The number of axles a vehicle has depends on how many wheels it has. Most cars have two axles—one for the front wheels and one for the rear wheels. However, larger vehicles, like heavy-duty trucks, often have multiple sets of axles to support their greater weight.

If you're curious about how to determine the number of axles on a specific type of vehicle, all you have to do is look at it from the side. Generally, vehicles have one axle for each set of tires. If you can see two wheels, the car has two axles.

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Types of axles

While axles are essential components for any car with wheels, not all axles are the same. We can separate axles based on two factors, function and position. The two categories of vehicle axles based on function are:

Live axle. Live axles spin with the wheels and transmit engine power to the wheels. They are usually connected to a differential or gearbox.

Dead axle. Dead axles are solid beams that support the vehicle's weight but do not spin.

We can break automotive axles down into more categories based on their location. Let's take a look at the most common types of car axles and their uses based on position.

Front axles

Front axles are located in the front of the car and can be dead or live, depending on the vehicle's wheel drive type. Front axles typically assist with steering and shock absorption and support the weight of the front of the car.

The two main types of front axles are:

Live front axle. This type of axle delivers engine power to the front wheels via the gearbox. All-wheel-drive and front-wheel-drive cars use live front axles, and many modern vehicles use constant velocity joints—also known as CV joints or CV axles—to deliver power to the front wheels.

Dead front axle. These axles are standard on rear-wheel-drive cars. Their purpose is to support the weight of the vehicle's front end, and they do not rotate with the wheels.

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Rear axles

Rear axles are positioned in the back of the vehicle and connect to the rear tires. They are often responsible for carrying engine power to the wheels and come in two halves known as half shafts. The half shafts connect to the rear differential, which connects to the transmission via the drive shaft.

Like front axles, rear axles can be live or dead, depending on the car's drive type. From there, rear axles are categorized based on the support and mounting methods they use.

These are the three most common types of rear axles:

Semi-floating axle. This is the simplest and cheapest type of axle and is commonly found on cars, SUVs, and light-duty trucks. It connects to the wheel via a flange on the outside of the axle shaft and has two bearings. The first bearing supports the axle shaft, and the other is located inside the axle casing.

Full-floating axle. Larger, heavy-duty trucks and some four-wheel-drive vehicles rely on this type of axle. It has two bearings and is designed to transfer driving torque only.

Three-quarter floating axle. This type of axle is similar to the semi-floating axle but has a bearing between the hub and axle housing and does not have a flange. Three-quarter floating axles are more complex and expensive than semi-floating varieties but are also more reliable and help maintain wheel alignment.

Stub axles

Stub axles—also known as stud axles—can be located in the front on rear-wheel-drive cars and in the rear on front-wheel-drive cars. The four main types of stub axles are:

Elliot. This axle uses a kingpin, a yoke, and a cotter to connect to the front axles.

Reverse Elliot. This axle uses the opposite arrangement of a standard Elliot.

Lamoine. A Lamoine stub axle has an L-shaped spindle and a kingpin instead of a yoke-type hinge.

Reverse Lamoine. This stub axle has the reversed layout of a standard Lamoine.

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What are the signs of a bad axle?

As we mentioned previously, axles are essential vehicle components, and you must keep them in good condition. If you notice any of the following symptoms in your car, it could be a sign that you have a bad axle:

A loud clunking or clicking noise

Vibrations while driving your car

The car won't move forward or backward, even while running

Leaking grease beneath the car or on the inside of the wheels

If you encounter any of these problems, the wisest step is to take your car to a professional mechanic for diagnosis and repair.

How much does it cost to replace axles on a car?

If you need an axle replacement, the cost will depend on your car's make, model, and age, as well as your physical location and the extent of the damage. For a complete axle shaft replacement, the price should fall somewhere between $500 and $950.

Front axle replacements tend to be more expensive, with the average cost ranging between $500 and $800 for parts and labor. Rear axle replacements cost a little less and could cost between $450 and $650. If you need a CV axle replacement, you should expect to pay between $200 and $600.

On the other hand, if you simply need an axle repair and not a complete replacement, you'll likely spend a little less. For example, A CV boot replacement may cost you between $50 and $200.

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How much does it cost to replace a car axle?

Does car insurance cover axles?

Car insurance

may cover your axle depending on the cause of damage.

Axles are wear-and-tear items, which means they are subject to degradation over time. If your axle is damaged as a result of age, your insurance will not cover its repair. However, your car insurance policy may help you cover the repair or replacement costs if your axle is damaged in a covered accident or crash.

That's why it's so crucial to select a car insurance policy that includes

comprehensive coverage

and

collision insurance

. If your car is damaged in an accident and you don't have these forms of protection, you'll likely be left to foot the bill yourself.