Pull out of a parking space with the wheel cranked over and hear a click-click-click that speeds up as you do. That noise has one usual source, and once you know it, you will hear it in every parking lot in Charlotte. It is the outer constant-velocity joint on a front axle, and it is telling you it has run out of grease.
What a CV axle is
On a front-wheel-drive or all-wheel-drive car, each front wheel is driven by an axle shaft with a flexible joint at each end. The outer joint lets the wheel steer and bounce while still being driven. The inner joint lets the shaft change length as the suspension moves. Both are packed with grease and sealed by a rubber boot. The boot is the whole story: while it is intact, the joint lasts the life of the car. When it tears, the grease flings out, grit gets in, and the joint wears.
Reading the noise
Clicking or popping in turns
The outer joint. It is loudest in tight, slow turns under power, and it is on the side that is on the outside of the turn — so a click turning left is usually the right axle. It gets louder over months.
Vibration or shudder under acceleration
The inner joint. A worn inner joint produces a vibration that comes on with the throttle and goes away when you lift, often at a particular speed. People chase this as a tire balance problem for a long time. Our post on diagnosing noise and vibration by when it happens covers how the timing of a vibration narrows it down.
Clunk on take-off or when shifting between drive and reverse
Excess play in a worn joint, or an axle nut that has loosened. Also the pattern of a worn engine mount, which we test at the same time.
Grease on the inside of the wheel or on the suspension
A torn boot slinging grease. The joint may still be quiet. Catching it here, before the grit gets in, is the difference between a boot and an axle.
What else clicks in a turn
A worn wheel bearing hums rather than clicks, and it changes with the direction of a turn at speed, not in the parking lot. A sway bar link clunks over bumps rather than clicking in turns. A loose brake caliper bracket or a rock in the dust shield makes a scrape. A strut mount bearing makes a creak or a pop when turning at a standstill. We listen with the car on the ground and with it in the air, and the CV joint identifies itself quickly.
The repair
If the boot is torn and the joint is quiet, the boot can be replaced and the joint repacked. In practice a complete replacement axle is usually the better value, since the labor is similar and the new axle comes with fresh joints and boots. It is a driveway job on most vehicles: wheel off, axle nut off, lower ball joint or strut separated, the axle pulled from the transmission or hub, the new one fitted and torqued. On some vehicles we lose a little transmission fluid at the inner joint, which gets topped up. See our steering and suspension services.
Frequently asked questions
How long can I drive on a clicking axle?
A while, and it will get louder. A joint that is badly worn can separate, which leaves you stationary and can damage other parts on the way. Do not put it off past a couple of months.
Should I replace both sides?
Not necessarily. Unlike brakes, axles wear independently, and it is usually the one with the torn boot. We inspect the other one and tell you honestly.
Do you come to my part of town?
Across Charlotte, Cornelius and Indian Trail. Book a visit or call.
Serving Charlotte and Mecklenburg County. Call (754) 236-1714.
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