Rick's Free Auto Repair Advice

Ball joint

What is a ball joint?

The job of a ball joint

The ball joint sits on the outer triangular end of the control ball joint and control armarm and acts as a pivoting joint to attach the steering knuckle to the vehicle. The ball and socket arrangement allows the steering knuckle to rotate left and right, while simultaneously allowing the knuckle to move up and down. Ball joints consist of a hardened steel ball, a tapered stud shaft and a hardened steel casing filled with grease. A protective rubber boot connects to the casing and the stud to keep the grease in the ball and socket.

bal joint anatomy

How many balls joints do you have in your vehicle?

That depends on the type of suspension in your vehicle. Some vehicles have a short-arm/long-arm (SLA) suspension. In that design, there are two control arms and two ball joints. However, in a McPherson strut suspension, there’s only a lower control arm and one ball joint. The strut mount bearing at the top of the McPherson strut allows the wheel to turn left and right.

What causes ball joint failure?

The #1 cause of ball joint failure is damage to the protective boot that allows water and road grit to enter the ball and socket. The water washes out the grease and the road grit grinds away at the surfaces of the ball and socket.

However, even if the boot is undamaged, the ball and socket eventually wear after you’ve driven a between 70,000 and 150,000 miles.

Ball Joint failure

Symptoms of a worn or damaged ball joint

• Clunk noise, knocking noises, when going over bumps
• Creaks or squeaks when the suspension moves up or down or during turning maneuvers
• Drifting to the side
• Shaky or loose-feeling steering
• Uneven or premature tire wear or tread feathering

Is a worn ball joint dangerous?

Yes! Just like a worn hip joint, a worn ball joint can separate while driving, possibly causing a life threatening accident. When a ball joint separates, there’s nothing holding the steering knuckle and wheel to the control arm. When no longer attached to the control arm, the wheel can rotate and become horizontal, causing the vehicle to skid on the brake rotor, or it can rotate 90°, causing the vehicle to skid sideways.

Ball joint replacement cost

To replace a ball joint, the technician must separate the steering knuckle from the tapered stud. Then, depending on the design, either press the old ball joint out, or drill out factory rivets to remove and replace the ball joint. After the new joint is installed and reconnected to the steering knuckle, the vehicle must be aligned.

Ball joint replacement cost on a 2010 Chevy Silverado.

This vehicle has an SLA type suspension, so there’s an upper and lower ball joint.

gm 19255770

Genuine GM 19255770 Control arm

Generally, you should replace both at the same time. However, the upper ball joint in this vehicle cannot be replaced by itself, so the tech must replace the entire upper control arm with a new control arm/ball joint assembly.

GM 19256481 ball joint

Genuine GM 19256481 ball joint

The Alldata flat rate guide shows a labor time of 2.5 hours to replace the upper control arm and lower ball joint. A genuine GM lower ball joint lists for $93.58 and a GM upper control arm lists for $230.43. With an hourly shop rate of $120/hr, this job would cost $420 labor (including alignment) and $324 for parts. Total ball joint replacement cost: $744

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