How Does the CV Axle Work?

Here’s how different parts of a constant velocity axle ensure efficient power distribution and smooth steering:

• Inner CV joint: Positioned near the transmission, the inner joint facilitates axle movement as the vehicle’s suspension travels, ensuring consistent power transmission at varying angles.

• CV axle: Extending from the inner CV joint to the outer CV joint, the CV axle shaft delivers power to the wheels and maintains a constant speed during turns.

• Outer CV joint: Located near the wheel hub, the outer constant velocity joint transfers power to the wheel assembly. This allows the wheels to maintain a constant speed even when they change angles during steering maneuvers.

• CV boot: The CV rubber boot is a flexible cover that protects the outer and inner joint from dirt and debris.

Note: The CV axle joint is an integral part of the drive shaft of a front wheel drive car. Each wheel has two CV joints — one connecting the transmission to the axle and the other to the wheel.

Signs & Symptoms of a Bad CV Axle/Joint

1. Accelerating or Turning Makes Clicking Noise

One of the most common and noticeable bad CV joint symptoms is an audible clicking noise when turning or accelerating. When CV axles become excessively worn, the constant velocity joints will become loose and click when turning or accelerating. The clicks may become louder or more pronounced during sharper and faster turns and will be heard on the side with the faulty CV shaft. Alongside popping noises, you may also have a hard time steering while making turns and rounding corners.

2. Edge of Tire is Greasy

Another sign of a bad CV axle is grease on the inside edge of the tire or along the underside of the vehicle. A torn or cracked CV boot will leak grease that ends up tossed around while the axle turns. A leaky boot will eventually lead to CV joint failure, as dirt and debris will get into the boot and damage the joint. Should enough grease leak out, you may notice a growling noise from a lack of lubricant, as well as a steady knocking when driving at low speeds.

3. Excessive Vibration When Driving

Excessive vibrations while driving is another bad CV axle symptom. If a CV joint or axle shaft is damaged in any way that affects its balance while rotating, it will cause the shaft to vibrate excessively while operating the vehicle. The vibrations may oscillate, or become more pronounced as vehicle speed increases. Excessive vibration from failing CV shafts can interfere with handling and ride characteristics, and the overall safety and comfort of the vehicle. Usually, the CV axle will need to be replaced if it is damaged enough to cause vibrations. It’s crucial to buy a quality replacement CV joint if yours needs to be replaced to ensure long-term health of your vehicle.

4. Excessive Tire Wear

Another symptom of a bad CV joint is excessive wear on the edges of your tires. This can occur when the CV joint is not distributing weight evenly across the tire due to its inability to properly function. As a result, certain spots of your tire shoulder more load than others, leading to early tire wear. If you notice that your tires are wearing down faster on the edges, it's worth having your CV joint inspected by a professional.

How to Replace a CV Axle? 

Here’s the step-by-step process a professional mechanic would follow to replace a faulty CV axle:

1. Use a jack to raise the front of the car and secure it with jack stands for safety.

2. Next, use a lug wrench to remove the affected wheel and the axle nut.

3. In the engine compartment, disconnect the bad axle from the transmission.

4. Insert the new CV axle into the transmission and secure the other end firmly into the wheel hub.

5. Put the wheel back in place, tighten the lug nuts securely, and reattach the axle nut.

6. Carefully lower the car from the jack stands. 
7. Go for a test drive and ensure the vehicle operates smoothly.

How to Extend the CV Axle Lifespan?

Here’s how to reduce the likelihood of a broken CV joint, damaged CV joint boot, and CV axle failure:

• Follow the recommended maintenance schedule for your vehicle, including regular inspections and replacements of the CV joint boot by a qualified mechanic.
• Keep your tires properly inflated to avoid excessive strain on the CV axles.
• Avoid driving over potholes and rough roads to minimize axle stress.
• Avoid sudden acceleration, hard braking, and sharp turns, especially on uneven or slippery surfaces.
• Practice gentle steering movements rather than abrupt jerks, which can strain the CV axle shaft.
• Stay within your vehicle’s maximum load capacity, as overloading can place additional stress on the axles.
• Ensure that the CV axles are properly lubricated to reduce friction and wear.
• If you notice any symptoms of a failing CV axle shaft, have it inspected and repaired promptly to prevent further damage.
• When replacing CV axles, use quality auto parts that meet the manufacturer’s specifications.