ABOUT C.V. JOINT BOOTS

(CONSTANT VELOCITY)

A constant velocity joint boot is the component that covers and protects the constant velocity joint itself from the elements. A constant velocity joint is the actual bearing on the axle that allows the drive axles to turn while driving the vehicles front wheels. Front wheel drive and four-wheel drive vehicles have four of these boots. The most common boots to fail are the outboard boots because they are under the most stress.

Not only is it the ‘job’ of the C.V. boots to cover and protect, they also contain the grease which lubricates the C.V. Joint. If the boot becomes torn, the grease escapes and the joint will become contaminated with dirt. As with any bearing, it must be lubricated at all times with clean lubrication or it will fail.

Typically a C.V. Joint protected properly will last the lifetime of the vehicle. If the boot is torn and replaced promptly, there is no major effect on the service life of the joint. Torn boots that are not replaced promptly can allow the joint to fail prematurely. If the joint on an axle shaft fails it will make a distinct ‘clicking noise’ when turning the wheel and accelerating. If the noise is audible, the joint must be replaced. This usually doubles the cost and expense of the original repair necessary (replacing the C.V. boot only).

The repair process involved in the replacement of a boot is usually only a couple of hours time (per outer boot) and can be accomplished in less than one day even if there are two being replaced. While it is not as common, inner boots will fail also. It is best when replacing one boot on an axle, to have them both (outer and inner boots) replaced if the other is showing signs of fatigue. The additional expense is minimal in comparison to having one replaced now and then the other on the same axle at a later date.

C.V. boots are not an item that is normally serviced at regular intervals. The replacement of a boot should only be done when one of the two boots on an axle shaft fails and should be done as soon as possible after failure to prevent the joint from premature failure. If you have waited until you can hear the ‘clicking noise’ when you are turning and accelerating, you have waited too long and replacing a boot only, will not help. The entire axle shaft needs replacement, almost doubling the expense of the repair. C.V. boots are important to your vehicles drive train.