what is a CV joint?
CV stands for Constant Velocity and the CV joint ensures that the wheels turn at a constant velocity, regardless of up and down movement in the car’s suspension.
Typical CV joint Kit will include CV joint grease and a CV boot CV joints are found on either end of the shafts that drive the wheels (often referred to as ‘half shafts’ or drive shafts in front-wheel drive cars), regardless of whether the car is front, rear or all-wheel drive. The inner CV joints connect the shaft to the transmission, allowing movement between them, while the outer CV joints allow movement between the shaft and the wheels.
Although CV joints are found on the back wheels (on rear wheel drive and four wheel drive cars) they rarely fail, so here we’re dealing mainly with CV joints on the front of front-wheel drive cars. The principle for changing them and their operation is the same, however. Likewise, the inner CV joints of a front-wheel drive car rarely cause problems, as they don’t have to move anywhere near as much as the outer CV joints, which must accommodate the steering of the wheels as well as the drive force from the engine. So we’ll focus on outer CV joints for the front axle in this article.
Complete driveshaft and CV joint assemblies
CV Joint Noise:
It doesn’t take a trained ear to pick up on the tell-tale clicking sound a worn front CV joint makes, though as the degradation is gradual it may be a while before the driver notices it. Park up on even and smooth ground with plenty of space to spare. Turn the wheel fully in one direction and ease the car forward, gently accelerating while holding the wheel steady. Repeat this in the opposite direction as well. A worn CV joint will emit a characteristic clicking sound under these conditions and it should be replaced before there’s any chance of it disintegrating completely. The noise gets louder as the component condition worsens.
CV Joint Replacement Cost:
Cv joints are not particularly expensive items to buy and can range from as little as £20 up to roughly £150. Depending on the car, the labour charge to fit them shouldn’t be that much either. Bank on half an hour to an hour per side to replace.
CV joints usually fail because the rubber boot that surrounds them gets damaged. This keeps the necessary grease in place and moisture and dirt out of the CV joint. These can tear and that will eventually lead to CV joint failure (a torn or damaged CV boot is an instant NCT/MOT failure by the way)
If you spot any damage on the CV joint boot, it’s best to have it (just the rubber boot) replaced as soon as possible, even if there is no CV joint noise. This could save you hundreds in the long run, though it’s still almost as much work to replace the boot as it is the whole CV joint. A CV joint boot kit will include the rubber boot, new band clips and a pouch of grease. Like this guide? Why not check out our other DIY guides here.