Clarity on Checking Ball Joints

My current question is general - not about a specific vehicle or problem of the moment. (I currently have 3 vehicles, all with FWD, struts in front, and lower ball joints only. 2 are bolt on, one is press in. I’m asking just b/c I periodically check things).

I have frequently seen people say that in order to check ball joints they must be unloaded by jacking under the control arm as close as possible to the ball joint.

But I also recently came across this:


In that article it says: “With MacPherson struts, the strut supports the load, so the lower ball joints are unloaded. To measure play, simply raise the vehicle and allow the suspension to hang free. Then push on or pry against the wheel to measure vertical and horizontal play in the lower ball joints.”

Obviously there are different ball joint & suspension set-ups, so I’m wondering if the general “jack under the control arm” advice is just a method that works for everything and is easier than explaining all of the different set ups and different ways of checking.

Or, perhaps this article is screwy.

If I just check for ball joint play anytime I have my front wheels up off the ground, does that work if I have struts in the front?

If the shock, strut, spring mounts to the lower control arm, the lower ball joint is under load. If the shock, strut, spring mounts to upper control arm the upper ball joint is under load.

Where the lower ball joint is under load, the vehicle is raised from under the lower control arm. This unloads the lower ball joint. If the upper ball joint is under load the vehicle is raised by the chassis so the suspension can hang. This unloads the upper ball joint.

Since almost all vehicles have struts with only lower ball joints those are the ones under load. So to check these the vehicle is lifted from under the lower control arm to unload the ball joint. Another way to check for a worn lower ball joint is, raise the vehicle until that tire is 5"-6" off the floor. Then take a 4’-5’ long pry bar or 2X4 and place one end under the tire. While someone observes the ball joint, lift up on the tire and release repeatidly. If the ball joint is worn it’ll be observed moving up and down in it’s socket.


I believe that with MacPherson struts, as you lift the car by jacking from the FRAME, the strut becomes fully extended and takes the spring load on its internal travel limit. This “unloads” the single ball joint, which is now supporting only the weight of the tire, wheel and brake…Testers 2 X 4 method will quickly reveal any slop in the joint…

Thank you both for the input & further education. Everything I learn seems to save me money and aggravation all at once.