If you suspect that you have issues with your differential on your vehicle you will likely be trying to isolate the issue. If you have specific popping, grinding or clicking noises whenever you are turning, then this may well be due to a failing CV. What is this and what should you do about it?

What's a CV?

"CV" stands for constant velocity and is generally the name given to the axles that transfer power from the engine to the driven wheels. These can be quite complex systems, as they have to put up with a lot of friction, movement, turning forces and differing speeds.

How Does It Work?

The CV "axle" is controlled by two different joints – the inner and the outer. These are the critical components as they allow smooth transfer of the power under every circumstance to the driving wheels. These joints are filled with grease to lubricate the moving parts within. They are in turn protected by rubber boots on the outside, which keep dirt and moisture away.

What's at Risk?

Usually the axle itself is very durable and the CV joint itself is the component that can typically fail. In turn, this failure is often caused by damage to the rubber boot. Sometimes, this can fail due to normal ageing, but often debris from the road can cause damage.

Because it is less protected, the outer CV joint is more vulnerable to failure due to damage in this way. It is also exposed to more external forces due to turning and movement.

Different Noises

Noises that you hear can be caused when the CV joints themselves are failing. This is especially evident during turning as this is when they come under the most pressure. In very low speed situations a failing CV joint can cause a rhythmic knocking sound every two seconds or so. Alternatively, you may notice a steady vibration through the steering wheel when you're travelling at certain speeds. 

Having a Look

To make a quick visual inspection yourself park the vehicle and make sure that it is on level ground, with the emergency brake on. Turn the front wheels inward if you suspect the issue is at the front of the car. You can then look inside of the wheel at these axles and inspect the rubber boots. There are two on each side. If you see any cracks or tears then these need to be fixed as soon as possible. You may also see grease on the outside of the boot which is leaking from the interior.

Safety First

To be safe, take the vehicle to your auto transmission specialist who will be able to replace the joints and the axle if needed.