Changing CV (constant speed) axles today is almost as common as doing brake work. But some CV axles can be quite difficult to remove. In this article, learn some of the tricks I’ve used over the years as a Master Tech to make changing CV and 1/2 axis easier. Sometimes special automotive tools are needed to make the job easier, I will discuss some of them and whether it is better to replace the entire half shaft, the joint or just the CV boot.
Clicking turns
Since you’re reading this, you may already know that a common sign of a bad CV joint is popping and clicking in turns. A jerk on straight takeoffs could be a worn internal joint, but this is much less common. The outer joints have the most movement (such as in turns), so outer boots tend to wear more than inner ones. CV boots are designed to pump grease throughout the joint during movement. The wear that causes the outer joints to make noise can be accelerated if the CV boot breaks due to dry rot or wear and the lubricating grease is lost. If the CV boot breaks, centrifugal force throws grease out of the joint while driving. Without grease to keep the joint lubricated and cooler, its life is drastically reduced. Also external elements such as moisture and dirt can enter the joint, further reducing its lifespan. Once they wear down, they make a clicking noise when turning while accelerating. If they are noisy, the 1/2 shaft assembly may be the easiest way to go instead of just replacing the gasket. CV 1/2 axle prices have dropped in the last decade and are more widely available than ever before.
Half Shaft Assembly Removal
The job of removing the axle shafts on most cars is pretty much the same.
- Remove the large nut that holds the linkage to the wheel hub.
- It may be necessary to unbolt or unhook the brake hose to prevent stretching when removing the axle.
- The steering knuckle (where the brake rotor mounts) must be loosened at the strut mount or lower ball joint to allow the axle to slide out of the hub. Choose the easiest!
- The inner CV will be attached to the transmission by bolts or with a retaining clip (clip is not visible).
- If there are no bolts in the inner joint, in most cases it will be necessary to pry it out with a pry bar.
- Alternatively, a slide hammer with a CV joint puller can be used to remove the inner joint from the transmission.
Boot inspection and replacement
You may be able to spot and replace worn boots before the CV joint is damaged. If the boot has dry rot and is about to crack or has recently split. And the CV joint still doesn’t make a noise, it was caught on time. The CV half shaft assembly can be removed and of course you can just replace the boot with new grease. The CV boot kit also comes with two clamps and special grease. It’s less expensive to restart a joint, but requires a bit more manpower. On cars I was familiar with, many times I’ve changed the CV boot without taking the axle all the way out of the car. Usually, however, the shaft is removed and placed on a target to work on. The old boot is cut away to help reveal what type of retaining clip holds the joint on the 1/2 shaft.
When using a cleaner, such as brake cleaning and the joint is at an angle, it is easier to see the clip. It may be necessary to rotate the joint while holding it at an angle to see the clip. Most require lock ring pliers to spread the lock ring or the joint can be tapped with a hammer (care must be taken not to damage the cage). If in doubt about what type of retainer you are working with, consult a service manual for your specific model. Note that ball bearings can fall out when the joint is off the shaft and the cage is turned sideways, depending on what type it is. After cleaning and drying with compressed air, the grease bag can be cut at the corner, and the grease is squeezed into the center of the joint. It is common to force out some of the old grease that was trapped by doing this. Collect and dispose of any old grease that may leak out. Replace the sleeve and gasket on the shaft by separating the clip or tapping lightly with a brass hammer. Special CV joint bellows clamp tools will be needed to tighten the bands properly. There are two basic types of clamps. There is a type that will crimp with some boot clamp pliers. The other type requires a banding tool, this type rolls up and tightens using the same motion as you would a can opener.
A common mistake is damaging the output seal on the transmission when removing or reinstalling the shaft. If the seal is damaged, the transmission fluid will leak. Be careful to center the inner gasket when you replace it. Also a mistake even professionals make is breaking the cir-clip that holds the shaft in the drivetrain or not installing the shaft all the way IN. It is normal to feel a slight in and out movement when pushing and pulling on the inner seal when it is properly installed. If the retaining clip is broken or not fully inserted, the axle can slip enough that the car will not move! Also, if you push the shaft back into the transmission, be careful not to strip the outside threads. Remember, if this is your first shafting job, don’t hesitate to have an experienced colleague on call!
