Understanding your car's axles
By Allstate
Last updated: February 2023
What is a car axle?
An axle on your vehicle is a rod or shaft that rotates the wheels and supports the car's weight. The engine powers the axle, which in turn delivers power to your wheels. For this reason, axles are absolutely critical to a vehicle’s drivability.
What are the different types of axles?
There are typically three types of axles – the rear, front and stub axle.
Rear axle
The rear axle is located between the differential and the driving wheels and transmits power between the two, according to The Engineers Post. The rear axle is actually two halves — connected by the differential — with each part known as the half shaft. In most vehicles, the rear axles rotate with the vehicle's wheels.
Front axle
The front axle helps with steering, absorbs shocks from driving on uneven road surfaces and carries the weight of the front part of the vehicle. It’s made up of 4 main components, says Car and Driver. These are the beam, swivel pin, track rod and stub axle.
Stub axle
These carry the front wheels of the car, according to The Engineers Post. The front and rear axles are responsible for rotating the wheels. Most cars have front and rear axles, although larger vehicles might have more.
Why should you inspect your axles?
Regular axle inspection is an important part of car maintenance because spotting trouble early on can help you avoid expensive repairs in the future, according to Meineke. The cost of axle repair can increase drastically if you have to replace any of the axles.
How often should you check your axles?
It’s recommended that you check them at least once a year (even more on higher mileage cars), as parts like the axle boots (or CV Boots) can wear out, according to J.D. Power.
What to look for when inspecting axles
Most car mechanics will inspect your axles whenever you bring in your car — but you can also conduct an inspection yourself, according to Car and Driver. You won't need any tools to do it, but you will need to get underneath your vehicle. Depending on how low your car is, you might need something to lift it up off the ground. You can use car jacks or vehicle ramps to do this.
Visual inspection
The easiest part of the inspection is taking a close look at the boot, which is responsible for keeping joints lubricated and preventing dirt and water from getting in, says YourMechanic.com. The boot has ribs which allow it to flex and move with the vehicle. Check for holes, splits or grease leakage. Next, you should inspect the shaft for any nicks, dings or dents, plus signs that anything is rubbing on it.
YourMechanic.com also recommends that you check the clamps that connect the boots to the shaft to ensure there are no leaks.
Driving inspection
You can also take a test drive to determine if there’s anything wrong with your axles. If you notice any of the following signs, says Meineke, your axle might be in disrepair when:
- There is a loud "clunk" sound once you put your car into gear.
- Your car vibrates/shakes if the engine is on.
- There is a clicking or popping noise when you turn on your car.
- Your car is running, but it won't move forward or backward.