CV Axles, Boots & Joints

How to Identify the CV Axle, Boot and Joint?

CV axles, or constant velocity axles, are specialized drivetrain parts that transmit motion from the transmission to the wheels of your front-wheel, rear-wheel or four-wheel drive. Most commonly found in front-wheel vehicles where engine power is dispersed at the front tires, CV axles make driving possible.

On the end of each CV axle is a CV joint, a mechanical connector that plays a role in the ability to accelerate while turning your vehicle by allowing the power generated from your transmission to expand the steering range of motion through bearings. These joints link the axle to the transmission and wheels, transferring torque to achieve a consistent and smooth level of driving as you steer beyond just a straight line. CV joints also stabilize the driveline as you cross over road bumps and take sharp turns. In short, these critical components keep your CV axle from breaking apart as you drive across uneven terrain.

There are two main types of CV joints: a ball-type joint and a tripod-type joint. All CV joints are coated in a heavy-duty grease that will protect the CV shaft from intense friction, sliding, shock or impact loading. These joints are also encased in waterproof boots made of a flexible, rubberized or plastic material that can withstand harsh temperatures and keep grease packed inside of them. CV joint boots keep moisture and grime out, while maintaining internal lubrication to prevent corrosion. While CV boots are made with durability, their location and function put them at risk of premature deterioration that is dangerous if not addressed early.

Signs You Need Drivetrain Maintenance

The most common issues regarding the CV assembly are usually related to the CV boot. While the CV boot is a heavy-duty, protective covering, it is still susceptible to tears and cracks that will excrete the grease and let in the grime! This leads to quicker joint deterioration due to the loss of lubrication. Dark grease stains and drippings around the boot clamps are signs that this is occurring. A loud clicking or popping noise when accelerating is also a common symptom of a worn CV joint.

Because these are vital components of your vehicle's steering ability, and can come apart when driving, CV boots should receive regular inspection for deterioration by your trusted service and repair mechanic. Addressing an impaired CV boot is sometimes as easy as using a packet of fresh grease to loosen things. Check out the "How to Grease a CV Axle" article for a detailed guide on greasing tips and tricks.

However, if your CV joint completely fails, then you are unable to drive your vehicle and a full replacement is necessary. If the situation is severe or left untreated, then you may need to replace the entire CV axle assembly, which is labor intensive and requires an inventory of a jacks, jack stands and certain tools like a torque wrench. The manual labor and heavy-duty equipment required to safely replace a boot, joint or axle is possibly too much hassle. That's why your local NAPA AutoCare Center is equipped to take on any task that the casual DIY-er can't handle.

Additionally, your nearest NAPA Auto Parts store carries quality tools, parts and knowledge to equip you with a revitalized assembly whether you need a diagnosis, some extra grease or a comprehensive CV axle, boot and joint replacement. Shop NAPAOnline for great deals and get Free One-Day Shipping on 160K+ parts for fast, reliable service or easily buy online and pickup in store.