What is a CV Joint?
A CV joint is specialized type of universal joint called a constant-velocity joint. Your wheels move up and down with suspension travel, and the front tires have to turn left and right for steering. That requires a pair of articulated joints for each wheel. There’s an inner joint, right next to the transaxle, and a second joint right out by the wheel. They’re connected by a short, round bar of metal, called an axle shaft. These joints are lubricated with a special grease, and are covered by a flexible accordion-pleated boot. The boot keeps the grease inside and dirt outside.
What are the symptoms of a bad CV joint?
The normal failure mode of a CV joint is caused by a split-open boot that lets the grease escape. Vehicles with very high mileage may simply have dried-out grease inside an intact boot, however. Regardless, as the grease fails to provide adequate lubrication, the joint starts to wear with increasing rapidity.
- The first sign is a clicking noise during parking maneuvers or during tight turns.
- Combine some sharp turns with a modest amount of throttle, and all the extra clearances caused by wear should start to click rhythmically.
What is the severity of a failed CV joint?
Eventually, the wear inside the CV joint will get so large the joint will no longer transmit torque from the engine to the wheel. This will instantly make your car undriveable. You’ll need a tow to a shop for repairs. If the CV joint’s boot has failed, but hasn’t leaked all of the lubricant yet, you may be able to save the cost of a replacement axle. Your mechanic should be able to spot the line of thrown grease that’s exited the boot easily. Note - CV grease is a distinctive black color.
One item to keep in mind, generally, it is not cost–effective to replace a single CV joint. Most often the other joint has seen just as much abuse and wear and tear as the one that’s failed. And the labor to replace the entire axle assembly is the same—or even a little less—than removing the axle, changing the bad joint, lubricating the other joint, and then reinstalling the used axle.
Generally, a good mechanic will simply swap in a fresh or remanufactured axle assembly, with two CVs, new boots and pre-filled with the appropriate lubricant. A new axle, exchanged for your rebuildable used one, will cost $40-400 dollars for parts. Labor to remove and replace a single axle should run from $50-200. If you car has significant mileage, consider doing both axles and all four joints at the same time. If you’ve got a boot that’s been split open by road debris at a low mileage, you might consider doing only one side.
A simple split boot that hasn’t expelled all of its grease yet may be a candidate for a simple boot swap. The cost for this should be $50-100. Be prepared to upgrade this repair to a whole new axle assembly if inspection of the joint in question reveals any damage caused by inadequate lubrication or dirt/water intrusion.
Need schedule a CV joint replacement? Start with Openbay first. Compare pricing from local shops and book service online in minutes. Openbay is car repair for the modern world.