Playing Ball: Servicing Ball Joints the Right Way
Just like all steering and suspension system components, the ball joint is a safety-critical part. A worn ball joint can compromise a vehicle’s ride and handling. In the event of a failure, however, the results can be much worse. As an industry leading supplier of steering and suspension components, Delphi can provide an insight into the role of the ball joint, what to look out for in a failing joint and how to replace it before it gets that far.
What is a ball joint?
The ball joint is an essential part of a vehicle’s steering and suspension system, that is typically used in the front end. Put simply, it acts as a pivot between the vehicles wheels and suspension, allowing the vehicle to be steered, whilst also ensuring a comfortable ride. Since the ball joint constantly pivots through multiple planes and angles, much like a human hip joint, it is subject to significant stress and wear.
What are the different types of ball joint?
There are two types of ball joint. Why is it important to know this? Because they require slightly different approaches when it comes to servicing. Most vehicles are fitted with MacPherson strut suspension systems. This incorporates a single ball joint on each side, positioned between the lower end of the strut and the control arm.
In double wishbone systems, the two joints are located at the top (upper ball joint) and bottom (lower ball joint) of the suspension system. Given its position, the lower ball joint experiences higher loads as well as increased exposure to dirt and salt, resulting in faster wear.
How to spot a failing ball joint?
Although ball joints are designed to be highly durable, over time they will gradually wear and require replacing. Whilst ball joint replacement is not part of the routine maintenance schedule, they should be checked regularly and according to manufacturer’s intervals for any signs of damage and/or excessive free play. If either of these is present, the ball joint should be replaced. Other common symptoms of a worn ball joint include:
It is therefore recommended to check the ball joint, and replace where necessary, if any of these symptoms are evident.
Why is it important to replace the entire ball joint and not just the boot?
A common cause of ball joint failure is the splitting or cracking of its rubber boot. When this happens, water, salt and dirt penetrate the joints internal components, damaging the boot. In this instance, it’s advisable to replace the entire ball joint, as a new boot would likely seal in the damaging substances, resulting in accelerated wear and corrosion.
Additionally, the ball joint is designed to operate with a grease lubricant, which is sealed and intended to last the life of the joint. A defective boot could lead to loss or heavy contamination of this essential lubrication. Without a form of lubrication, the friction within the joint increases significantly, which can cause the steering to become heavy or stick. It is worth noting that the ball joints on some older vehicles are serviceable and require lubrication periodically.
How-to replace a ball joint?
To ensure a quality steering and suspension repair, it’s best practice to follow the steps below when it comes to ball joint replacement: