4 Symptoms of a Bad Synchronous Axle (Half Wave)
All passenger cars and trucks have a way of transferring power from the engine to the wheels. In most modern passenger cars (except most two-wheel drive pickup trucks), this method uses two or more constant velocity (CV) axles.
In this article, we’ll discuss the most common symptoms associated with a failed synchronized axle, what causes it to fail, and how much it costs to replace it.
Symptoms of a Failed Synchronous Axle
Paying close attention to your car while driving and operating can help you spot emerging problems long before your car breaks down on the side of the road. Keep in mind that problems with CV axles are exclusively due to wear and failure of the CV joints, since the CV axle itself is nothing more than a precisely machined cylindrical steel rod. The following signs are typical issues with CV joint shafts:
#1 – Abnormal noises at low speeds
When making sharp turns at low speeds, you will hear a clunking, popping, or clicking noise on the right or left side of your car. It can happen when backing up. For example, when you drive out of the garage and make a sharp left or right turn.
#2 – Abnormal noises when accelerating
The same noise occurs when accelerating moderately to suddenly, especially when turning gradually to the right or left.
#3 – Vibration in the steering wheel
You may feel an intermittent vibration in the steering wheel when accelerating or driving at high speeds. This vibration can be confused with vibration caused by wheel imbalance.
#4 – Grease your wheels or tires
Each CVJ is sealed inside a flexible rubber or plastic bellows. This bellows contains grease that lubricates the joint. Over time, this bellows can crack or tear, and the lubricant will just come right out (it will fly away due to centrifugal force).
Noticeable symptoms include dirt or dirt droplets on the garage floor or on the inside of the wheels and tires. If these are found, a detailed visual inspection of the corresponding axle boots is required. Cracks and tears are easy to spot. If you are unable to perform such a check, we recommend that you immediately consult your local service technician.
Note: After every oil change, have a service technician check the axle boots for damage. Quality repair shops that perform safety inspections at the time of oil change usually include such an inspection; however, it’s a good idea to specifically ask them to do so.
What are synchronized axles?
A constant velocity axle is the last shaft in a series of drive components that delivers power to the wheels. For vehicles with all-wheel drive (AWD) independent front and/or rear suspension, axles with constant velocity joints (so-called half shafts) are usually used on all four wheels. Vehicles with front-wheel drive (FWD) or rear-wheel drive (2WD) and independent suspension also use these drive axles.
Each CV axle has two CV joints, one on each end of the axle. These joints connect and align the input and output ends of the drive axle to adjacent rotating hardware in the driveline.
The constant velocity joint design allows the input and output sides to rotate at the same speed, transmitting power across the rotating interface; hence the descriptive term “synchronous” in the part’s name. What causes a CV joint shaft to break?The above symptoms are typical of a CV joint shaft showing signs of wear, but the car may still be drivable. A completely worn CV joint shaft blocks. The car will then be unable to be driven and will have to be towed.
Warning
A CV joint shaft exhibiting any of the above CV joint shaft symptoms can fail completely (lock up) at any time. This can cause an axle break and lead to loss of control of the car resulting in a serious accident.
#1 – Man
Almost everything wears out over time. With enough mileage, the mechanical parts of a synchronized axle will fail. You can expect the lifespan of these devices to be around 100,000 miles of normal driving.
On some vehicles, the axles last for over 200,000 miles. During competitions and off-road driving, constant velocity joints wear out faster.
#2 – Driving in deep water
We frequently drive through water up to the depth of the wheel hubs of our cars. Very few drivers experience this situation. However, when we do this kind of driving, water can get into the axle boots of the constant velocity joints. This can cause corrosion and accelerated wear of the constant velocity joints.
#3 – Axle Boot Failure
When boots tear or rip, the joint loses lubrication and becomes contaminated by abrasive road dust. These conditions lead to rapid wear and mechanical failure of the joint.
How long can you drive with a defective axle boot?
The remaining life of a worn axle boot before it completely fails and seizes up depends on the degree of wear when you first notice any of the symptoms above. If you experience any of these symptoms for the first time, it’s best to take your car to a service technician as soon as possible.
Can a defective CV joint shaft cause damage to your transmission or differential? Although rare, a defective CV joint shaft that causes an axle break can damage your car’s transmission or differential. Such damage can significantly increase the repair costs required to get your car back on the road.
