Enclosed in a steel housing, ball joints are used on the front end of almost every car, truck, SUV, and minivan. As might be expected, ball joints are subject to a lot of wear and tear, so to properly protect them ball joints are housed in an enclosed boot to keep dirt away from the joint assembly.
There are two types of suspension systems that use ball joints. The first is a conventional system that uses an upper and lower ball joint. The second is called a MacPherson strut system that uses a single lower ball joint and an upper strut bearing. No upper ball joint is needed as the upper strut bearing does the job instead.
Maintenance for ball joints has changed over the years for most cars. Many vehicles come equipped with ball joints that are permanently lubed, so lubrication is not necessary nor is it even possible as the pack that holds the lubrication is permanently sealed. When ball joints wear out or are damaged, you can find replacement ball joints that come with lubrication fittings; in this case you would need to lubricate your ball joints on a regular basis as in when you change your vehicle's oil.
When performing an inspection of your car's suspension, your ball joints should be looked at too. Have a complete wheel alignment performed and make certain that the ball joints are not worn. If the ball joints wear out and are not changed, you will soon experience uneven tire wear or unreliable steering, such as wandering. Clearly, worn out ball joints are a safety issue that must be tended to and fixed immediately.
Ball joints are developed for the specific make/model of your vehicle. Many models share the same suspension system as other models within the brand, but to be sure check your vehicle's repair manual for the right replacement ball joints. Certain manufacturers, such as Moog, develop ball joints for many makes/models and can be used by mechanics that prefer this particular product. Check online to find out more information about Moog ball joints and whether they are right for your car.
Remember: ball joints are an important part of your vehicle's suspension system. Annual check ups of the suspension can head off costly problems which can also impact your safety.