Ball Joints & Components

Your legs would be useless without your hips, knees, and ankles. These joints connect your thighs, calves, and feet and allow them to articulate so you can walk, run, kneel, and sit down. The same relationship exists between ball joints and bushings and the control arms and steering knuckles and spindles in your vehicle’s suspension. The ball joints and bushings enable suspension motion in response to the tires’ contact with bumps, the springs’ corresponding reaction, and your steering input.

But where bushings only allow control arm movement in one plane, swinging up and down at the frame, ball joints enable the control arm and knuckle to move vertically and the spindle to move horizontally. A typical ball joint consists of a ball stud in a socket housing mounted to the control arm, with a rubber boot enclosing the socket to protect it from dirt and retain lubricant. The stud attaches to the knuckle/spindle and the ball allows it to both pivot and rotate as the vehicle is steered and the suspension reacts to the road.

It is common to refer to ball joints as uppers or lowers according to their mounting location, but a more important distinction that alludes to their function and construction is whether they are load bearing (loaded) or non-load bearing (unloaded) or “follower” ball joints. Loaded ball joints support the weight of the vehicle like the lower ball joints on rear-wheel drive vehicles with Short & Long Arm (SLA) suspension. Unloaded, or follower joints keep parts in alignment but do not support weight. The upper ball joints on SLA suspension vehicles and the lower ball joints on front-wheel drive vehicles with MacPherson struts are follower ball joints.

Ball joints wear from use, lack of lubrication, and boot failure that allows contamination into the joint. Common symptoms of worn ball joints are noise, abnormal tire wear, misalignment and steering problems like pull. To inspect loaded joints like the lowers on an SLA suspension, relieve tension by supporting the vehicle at the lower control arm, then check vertical and axial movement with a dial indicator and compare with specs. Some load carrying joints have built-in wear indicators - replacement is necessary when the indicator is flush with or has receded into the base of the joint. Some follower joints are checked for play while others are checked by measuring the torque needed to rotate the stud after disassembly.

Ball joints can be a press-fit in the control arm, screwed in, or retained with bolts or rivets. The stud may be tapered and fit into a tapered hole in the steering knuckle, or straight and be retained with a pinch bolt. Press-fit joints can be removed with a suitable press and fixtures. The rivets on riveted joints must be chiseled or drilled out, and replacement ball joints come with fasteners for retention. Original equipment ball joints on most new vehicles are sealed for life, and although some applications are serviced with the same type of joint, most of our replacement ball joints are greasable. Periodically injecting fresh lubricant flushes away old worn grease and contaminants, prolonging the life of the ball joint.

In addition to providing a complete line of direct fit replacement ball joints that meet or exceed OE quality, we also offer ball joints designed to solve particular vehicle problems. For example, if you’ve modified your suspension for greater travel, such as with a lift kit, we offer ball joints with greater stud articulation to prevent failure, and if your vehicle has no provisions for camber or caster adjustment and you’re experiencing abnormal tire wear and/or poor handling, we offer adjustable ball joints that can bring alignment within specifications. And if your ball joints cannot be serviced separately, we also offer complete control arm assemblies that come fitted with new ball joints.