Your axles' main job is to transfer power from your engine to your wheels. They are strong parts that can last a long time if properly maintained. Eventually, your axle will wear out over time and need to be replaced. Sometimes, an axle seal can leak and let water into your wheels, which can cause you axle to fail. A failing axle can cause your wheels to lock up, which can result in costly damage to your car’s transmission, and can even cause an accident.
So if you hear a strange noise coming from your axles, it’s important to get it looked at as soon as you notice the problem - waiting will only make the damage worse.