Everything You Need to Know About Ball Joints | Ultimate Guide
The ball joint is a safety-critical part, just like all the steering and suspension systems. 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.
What to look out for in a failing joint and how to replace it before it gets that far.
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 vehicle’s 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 wears.
There are two types of the 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.
Suspension Type | Upper Ball Joint | Lower Ball Joint |
---|---|---|
Both upper and lower control arms with spring on lower control arm | Non-load carrying | Load carrying |
Both upper and lower control arms with spring on upper control arm | Load carrying | Non-load carrying |
McPherson struts | Non-load carrying | Non-load carrying |
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 the 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.
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 joint’s 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.
To ensure a quality steering and suspension repair, it’s best practice to follow the steps below when it comes to ball joint replacement:
TIP: Ball joint parts made fromlow-grade steel or using inferior heat treatment can lessen the price, but also reduce the lifetime of the part by up to 50%.
Settle the vehicle on its suspension and check the wheel alignment including camber, adjusting.
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