CV actually stands for 'constant velocity' joints. All front-wheel drive vehicles have CV joints. They can also be found in many rear-and four-wheel drive vehicles as well. These CV joints are attached to both ends of a drive shaft. The CV joints help to transfer the toque at a constant rate to the wheels. They also are needed to help out with the up and down motions of the suspension. Driveshafts with CV joints are self-supporting.
Types - There are several common types of CV joints. The two most common are the ball-type and tripod-type.
Ball-type CV joints – there are different variations of the ball-type CV joints but they are commonly used on the outer side of the drive shaft. This type of joint is extremely flexible and can handle a lot of angle shifts when the front wheels are being turned by the steering wheel.
Tripod–type – this type of CV joint is usually found on the inner side of the drive shaft. This type has a three-pointed yoke that is attached to the shaft with barrel shaped rollers on the ends. These rollers fit into a cup attached to the differential with three matching groove
Problems of the CV joint
The CV joint is packed with grease to help it function better and it is protected by a rubber or plastic boot. There is little to no maintenance required and has the extra benefit of an extra long life expectancy as long as the boot remains intact.
If this protective boot does become damaged then problems can develop. When this happens, the grease locked inside drips out and the opening allows moisture and dirt to get in. These two issues will eventually cause the CV joint a lack of lubrication and corrosion problems.
It's a simple enough repair if the damaged boot is found early enough. The CV joint boot can be replaced and the joint can be repacked with fresh grease. If however the damage isn't caught early on then the entire CV joint will have to be replaced. In terms of the worst case scenario, the CV joint may come apart and cause the vehicle to stop running.
Symptoms of a CV joint problem
As a general rule, CV joints are reliable. The main failures of this type of joint are wear and seizure. Wear in the outer joint can first show as a vibration. If you think, the problem could be a CV joint, go someplace where you have some space and slowly drive in very tight circles, first left and then in the right direction.
While turning, listen for a clicking or popping noise while applying power. If the problem is severe, it will also happen when you lift off the throttle the vehicle is turning. This noise indicates CV joint problems. If there is a partial seizure, it can cause a strange 'pattering' sensation in the suspension. This can be the result of the joint overheating. If it is overheating, then it's because the boot has split and the grease has dripped out.
These repairs can be done by purchasing a kit. The kit will include the grease, boot, and retaining clips. Some boots are assembled lengthwise so they can be fitted on the joints as they sit instead of having to take the whole system apart.
Regular checking of the rubber boots is required to make sure they aren't split or damaged in any way. If you have to take the vehicle in for an inspection, be aware that damaged CV joint boots will usually cause the car to fail a vehicle inspection.