Found in all front-wheel-drive and many rear-wheel-drive cars, constant velocity joints (CV joints) transfer torque from the Drive shaft to the wheels and permit the vehicle suspension system to move up and down without the passengers noticing each bump. CV joints are protected by plastic or rubber boots that hold in the grease the joints are packed in. If the boot fails, dirt and moisture displace the grease, impairing the joint. Inspecting the CV boots at the first sign of trouble can help save the CV joints and money in repairs.
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Park the car on a level surface. This isn’t for the sake of the CV boots or joints, but for your own safety.
Slide under the front of the car as far as possible. To make getting under the car easier, lie on a car creeper, a wooden or plastic board on casters.
Locate the drive axles. These shafts connect the wheels to the car’s transmission.
Look for the plastic or rubber boots at each end of each axle. These are the constant velocity boots, or CV boots. There are four in all.
Inspect the CV boots for signs of wear or damage. Cracks, rips, tears, splits or punctures all will permit the packing grease to leak out, while also letting dirt and moisture in. Also look for loose or missing clamps.
Feel the boots for leaking grease. If you detect grease, rub it between your fingers. If the grease feels gritty, it has been contaminated with dirt, and so has the CV joint. The joint itself needs to be inspected, cleaned and repacked with fresh grease; this is usually best handled by a mechanic.