A beautiful schematic of a CV joint, showing exactly how they work.
A beautiful schematic of a CV joint, showing exactly how they work.

How to care for your car’s CV joints

By Ken Corkett Time of article published Nov 29, 2011

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About 50 years ago when the Mini and its ilk began the front wheel-drive revolution, apart from some opposition by those who thought that ‘new’ equalled ‘wrong’, there were some genuine teething troubles, the main ones concerning the drive shafts.

The problem involved finding the best way to cope with transferring drive at all speeds in spite of constantly varying angles caused by steering and suspension.

Flexibility was obviously needed, so the initial answer was a cross-shaped rubber link with input and output shafts secured by U-clamps.

In reality this proved to be a poor solution.

Repeated flexing and an environment of heat and oil contamination guaranteed a short life for the rubber.

Also, when a joint failed, damage was inevitable as the loose end lashed about threatening the steering gear.

Eventually, the constant velocity (CV) joint we know and love took over and instead of failure at the 50 000km mark, may last around 160 000km provided they are kept clean and properly lubricated.

Because the joint is protected from the ingress of grit and dust by a rubber boot and runs in grease, no maintenance is necessary except for a regular inspection of the boot for damage or splits.

Failure to notice a split and renew the boot will inevitably result in the joint running dry and premature failure. Hence the reason why a roadworthy tester will fail a car with even a slight split in the boot.

There are two ways to cope with boot or gaiter damage. The easy way is to fit a split type; they’re universal and no dismantling is necessary. Simply cut to fit, slip over the joint and apply glue.

Personally, I prefer to fit an original equipment type. This involves a little dismantling, but I feel it is worth the effort.

Because of the gearbox location, drive shafts will often be of unequal lengths. Normally shafts have two joints, one near the gearbox and another at the wheel. The one near the gearbox deals with suspension movement and the one at the wheel deals with both suspension movement and steering. The latter may be renewed separately unless the manufacturer supplies only a complete shaft and joints assembly.

Check prices because although service exchange units may be cheaper if renewing the complete unit, when only one joint fails it makes sense to renew only that.

How do you tell if your CV joints are on their way out? Here we rely on our ears. While cornering, especially on full lock, the joint is under maximum stress and if there is any wear, you will hear a knocking sound.

On right hand corners, listen for knock on the left hand side and vice-versa. Knock is most noticeable on full lock; any noise means renewal is called for.

Do your homework and check prices. Breakers put aside good CV joints and generally sell them at equally good prices.

Aftermarket, OE or reconditioned prices should be investigated.

But in the latter case, go only to a place with a good reputation in the trade. There are some con artists out there. - Star Motoring

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