What Is an Axle?

It’s not the biggest part, but the axle can cause various problems for your ride if it’s damaged or broken. It could cause issues like sputtering noises, brake pad misalignment, excessive wheel vibrations, and oil leaks. Why does this component have such a huge impact on your daily driver?

Let’s find out.

What Does an Axle Do?

Car axles are central shafts that serve as a mechanical link between your transmission and your wheels. This solid shaft enables the transmission of power from the engine to the wheels. It also helps support the weight of the vehicle.

There are drive axles and there are just plain axles. Some provide a mounting point for the wheels and are sprung to the car body with suspension parts. Drive axles transfer power to the wheels, and on light trucks, they both transfer torque and support the weight of the vehicle.

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Pro Tip: Axle housings on heavier trucks (¾ ton and above) support the weight of the vehicle with the axle passing through the axle housing from the final drive to the wheel hub. These axles carry no weight. They only provide torque to drive the wheels.

Driveshafts vs. Axles

On a rear-wheel-drive vehicle, the shaft between the transmission and the rear axle assembly is called a driveshaft. This is according to the Society of Automotive Engineers (SAE).

General Motors (GM) and other manufacturers use the term “propeller shaft” or “prop shaft” to refer to the driveshaft.

What Is a Dead Axle?

The axle that transmits power to the wheels is commonly called the “live axle.” So what is a dead axle?

A dead axle simply supports the weight of the vehicle and helps maintain wheel alignment and stability. It can be found both on the front and rear of your vehicle, depending on the configuration. For example, rear-wheel-drive (RWD) cars usually have dead front axles.

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Not all vehicles have actual axles on the non-drive end. Some simply have wheel hubs connected to knuckles that are supported by links, with the upper part of the knuckle connected to the strut/spring assembly.

Types of Car Axles

There are three types of axles: front, rear, and stub. Let’s look at each type in detail:

Front Axles

As the name suggests, these axles are located at the front portion of the vehicle. Front axles are responsible for supporting the steering system of your vehicle. They also help absorb shocks caused by uneven road surfaces.

Rear Axle

The rear axle is usually between the rear differential and drive wheels so that it can transmit power between these components. In most vehicles, the rear axle rotates along with the wheels.

Rear axles are usually divided into two parts, and each part is called a half shaft. Most rear axles are live axles, but there are some vehicle configurations that have dead rear axles.

Stub Axle

A stub axle links the front wheels to the front axle. It’s usually on the vehicle’s front wheels, attached to the front axle using kingpins.

How Many Axles Does a Car Have?

It depends on the vehicle’s configuration. Most cars are generally equipped with two axles: front and rear.

Larger vehicles like heavy-duty commercial trucks can have more than two axles. The additional axles help distribute the weight of the cargo evenly.

If you’d like to know how many axles your vehicle has, you can review your owner’s manual or talk to a mechanic.

Can You Drive With Bad Axles?

You can, but it would be unsafe to do so, as broken or damaged axles can affect your brakes and acceleration.

What Are CV Axles?

Constant velocity (CV) axles are common in modern front-wheel-drive and four-wheel-drive vehicles. This axle assembly consists of shafts equipped with CV joints on both ends.

CV joints can rotate without altering speed. They allow for the transmission of rotational motion between shafts even when they’re not perfectly aligned.

However, these joints introduce a slight variation in speed when operating at angles (when making turns or traveling through rough terrains).

Basically, CV joints make it possible to transmit power from the engine or transmission to the wheels while accommodating changes in angle and speed.

Common CV Axle Issues

While issues with the axle itself are rare, the same does not apply to some of its related components like the CV boot.

The CV boot that surrounds a CV joint is usually made of rubber, hard thermoplastic, or urethane. These materials are strong and durable, but a CV boot can still rupture due to road debris, normal wear and tear, and lack of maintenance.

Grease on the underside of the vehicle is another sign of a bad CV boot.

Some of the other symptoms of a bad CV axle assembly include vibration while driving and clicking sounds when turning.

Can You Diagnose a CV Axle Issue Yourself?

To diagnose a CV axle problem, you’ll usually have to get under your car. Inspect the axle shaft for any signs of damage or excessive wear.

You can also inspect the CV boots for tears, cracks, or grease leaks, as damaged boots often lead to axle failure. If you want to inspect the joints, you’ll need to remove the driveshaft.

If you’re not an experienced DIYer, and you don’t have the tools to get the job done, it’s best to leave the diagnosis to a licensed mechanic.

How Often Should You Inspect Your CV Joints?

Experts recommend inspecting the U-joints or CV joints four times a year or every time the vehicle chassis is lubricated.

The U-joints in your vehicle are usually permanently lubricated and have no provision for greasing. If there’s a grease fitting, the U-joint must be lubricated by applying grease with a grease gun.

How Much Does It Cost To Replace a CV Axle?

A single axle replacement can set you back anywhere between $300 and $1,500, depending on your specific make and model. The part cost can vary widely, around $100 to $1,000, while the labor cost is between $170 and $180. 

A CV axle replacement can be pricey because it’s a complex process. It usually takes around two to three hours to get a single axle replaced. So if you’re going to have all four replaced, it can take up to twelve hours to get the job done.

Get Replacement Axles Online Before They Fail

Driving with bad axles is incredibly unsafe. There’s a chance it might fail, and when it does, your vehicle is going to be immobilized. There’s also a chance the axle can detach, causing it to get stuck on the road or suspension, which can steer your vehicle out of control. When your vehicle has symptoms such as vibration while driving and weird clicking noises when turning, you should have it checked immediately. If you’re sure you have a bad axle, then you shouldn’t hesitate to replace it. Need a replacement axle? CarParts.com has you covered.

CarParts.com has a selection of thousands of axles from a wide variety of aftermarket brands. All our parts have been stringently inspected and have passed all mandatory quality control standards. You can simply enter your vehicle’s year, make, and model and we’ll show you a list of components that are guaranteed to fit.

We also take pride in our competitive pricing. Check out our selection and order the right axle for your vehicle here at CarParts.com today.