A CV or constant velocity joint is a joint that connects a vehicle's transmission to the drive wheels of a car. The joint is called constant velocity because it is able to maintain the same speed even as it turn with the wheels in a car. A CV joint is covered in a lubricant and cannot be exposed to outside contaminants such as dust, or it will wear out prematurely. A rubber boot covers the CV joints of a car, but these boots can crack and wear out.
Popping or Clicking
If your car makes a popping or clicking noise only when it is going through turns, it is a sure sign a CV joint is wearing out. If you are not sure the clicking while you are turning is due to a worn CV joint, there is a test to confirm a CV joint is the cause. Go to an empty car park where you have plenty of space away from obstacles. Put the car in reverse, turn the steering wheel all the way to one side and drive backwards in a circle. Do this for each direction, left and right. If the click noise is louder when the car is turning in reverse, then the source is a worn CV joint.
Sometimes a CV joint is lacking lubricant so much it causes a humming or even growling noise while the car is driving on the road. This noise is constant while the vehicle is moving. There are other causes to these types of noises, such as worn shaft bearings in the transmission.
A worn CV joint can cause the vehicle to shudder. When the vehicle accelerates, too much movement in a CV joint can cause the vehicle to shudder, but so too can other problems such as worn engine mounts. A vibration that gets worse as the vehicle goes faster can also be from a worn CV joint. If it is not the CV joint, it could be from a tire that needs to be balanced.