HOW DO YOU KNOW WHEN A BALL JOINT IS BAD?
First, let’s review what a ball joint is!
A ball joint is composed of a ball and socket, where a polished metal ball is greased and seated inside of a socket. A rubber boot encloses the ball and socket to prevent grease from exiting and debris from entering. There are usually two or more ball joints in most vehicles. An upper ball joint that is a part of the upper control arm, a lower ball joint that connects to the lower control arm and knuckle, and there is one more ball joint commonly referred to as the tie rod that is attached to the rack and pinion. Now let’s find out if that ball joint is bad!
- It is important to address a bad ball joint as soon as possible! Here’s why:
- If too much time is allowed, the ball could separate from the socket causing the wheel or suspension assembly to detach and cause a serious accident!
- A bad ball joint causes irregular strain on the surrounding suspension components leading to a costly repair in the future.
One can typically identify a bad ball joint when there is a metal knocking or thumping sound appearing to come from one of the four corners of the vehicles or tires. This is most obvious around corners, over speed bumps, or at sudden stops. As time progresses, this sound may become more pronounced. This is caused by the ball moving around freely inside of the socket.
Fig. 1: Satirical Image of someone listening to ball joint noise with a stethoscope. (Photo by Roger A. Fleenor 2016)
Irregular Signs of Wear:
While this is generally uncommon, and usually caused by alignment related issues, bad ball joints may be the culprit if a tire is showing signs of inconsistent wear. The image below contains a great example of a tire suffering uneven wear. Notice how some of the grooves and tread on the right side of the photo are not visible compared to the left:
Inspecting the Ball Joint:
By steering completely to one side, you may gain access to view the ball joints for some vehicles. If not, this may require jacking up the vehicle: Remove the wheel to expose the entire wheel well. Perform a brief visual of the ball joints looking for seeping grease and cuts in the boots. If you drive a later model vehicle, ball joint wear indicators may be available to assist diagnosing the condition of the ball joints which is described at the next heading. The image below is a great example of a torn ball joint boot. The dark sludge around the arms is evidence of prior grease seeping which has dried and been coated with road grime.
Ball Joint Wear Indicators:
Many modern day ball joints are designed with built-in wear indicators. These are easy to identify by a small metal pin inserted through a small hole in the thread just after the bolt. The ball joint is often worse if the pin is missing, broken, or pinched. There is another type of wear indicator which is a thin wire that is wrapped around the base of the rubber boot. If this wire is no longer wrapped around the boot, missing, or appears unwound, the ball joint may be bad.
Examples of a loose and lost pin.
Examples of healthy pins around the boot and at the bolt:
Still can’t find the culprit?
While a ball joint looks visibly sound, it is possible that the grease inside the boot could have dried or the ball/socket is just worn from excessive impact or friction. You can distinguish the one bad ball joint from the two or more with the following exercises (you may need someone to help you!):
- Your assistant should listen closely to each side of the wheels looking for a knocking or thumping sound.
- Jerk the steering wheel left and right while the vehicle is on, if you are able to reproduce the knocking or thumping sound, then you know the ball joint on the tie rod is bad.
- Pull up to a fixed obstacle such as a speed bump, shallow curb, or gutter and slowly accelerate until the tires make contact with the obstacle without driving over it. Repeat this action gently. If you can hear something, the lower control arm ball joint is probably bad.
- No luck so far? This should be it! The upper control arm ball joint should be the source of the issue if the
Need a replacement part? Find your part by make and model at Benzeen Auto Parts:
- Used Front Drive Shaft
- Used Front Lower Control Arm
- Used Front Spindle Knuckle
- Used Front Upper Control Arm
- Used Hub
- Used Rear Lower Control Arm
- Used Rear Stub Axle
- Used Rear Upper Control Arm
- Used Steering Gear Rack
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Inform your mechanic or automotive professional of the quality used parts Benzeen Auto Parts has to offer!