The standard way to check a ball joint is to get the wheel off the ground and rock the tire to feel for play at the joint. That's simple in concept, but two details determine whether the test actually tells you anything: how you lift the vehicle (it depends on your suspension type), and which direction you rock the wheel (12-and-6 tests something different than 3-and-9). Get either one wrong and you can walk away with a false "it's fine" or blame the wrong part.
This covers that one test in depth. For the fuller inspection routine — including the visual boot check and when a passed shake test still doesn't mean "no action needed" — see our general ball joint inspection guide.
Step 1: Lift the Vehicle the Right Way for Your Suspension
This is the step most write-ups skip, and it changes what the test actually measures.
MacPherson strut suspension (most sedans, hatchbacks, and car-based crossovers): jack under the frame or a proper pinch weld so the wheel hangs completely unloaded and free. You want the suspension unweighted for this test.
Double-wishbone / short-long-arm (SLA) suspension (most trucks, body-on-frame SUVs — where the lower ball joint carries the load): the jack needs to go under the lower control arm so the suspension stays loaded while you test. On this type of suspension, testing with the wheel unloaded gives you a different (and less reliable) reading than testing it loaded, because the load-bearing joint's clearance changes depending on whether it's under weight.
If you're not sure which type your vehicle has, that's worth confirming before you start — the wrong lift point doesn't just give you a slightly-off reading, it can hide play that's actually there.
Always support the vehicle on jack stands rated for the job — never work under a vehicle held up only by a floor jack.
Step 2: The Shake Test — and Which Direction You're Testing
With the wheel safely off the ground (or loaded correctly, per Step 1), grab the tire and rock it:
- 12 o'clock and 6 o'clock (top and bottom): push and pull. This is the direction that isolates ball joint and wheel bearing play. Feel and listen for looseness, clunking, or a distinct "give" as you rock.
- 3 o'clock and 9 o'clock (side to side): this direction is more associated with tie rod end play, not the ball joint. If you feel looseness here but not at 12-and-6, that points you toward the steering linkage instead — don't assume it's a bad ball joint just because something feels loose.
Have a second person watch the ball joint itself (visible through the wheel well, behind the brake dust shield) while you or they rock the wheel. Visible movement of the ball stud relative to its housing — not just a feeling of looseness through the tire — is the clearer confirmation.
The Ball Joint vs. Wheel Bearing Trap
Here's the catch with the 12-and-6 test: a worn wheel bearing produces a similar-feeling movement to a worn ball joint, and the basic shake test alone doesn't cleanly separate the two. If you get play at 12-and-6, that confirms something is loose in that vertical plane — it doesn't by itself confirm which part. A dry, grinding wheel-bearing noise while driving (as opposed to a clunk over bumps) is one distinguishing clue, and a direct visual on the ball joint stud while rocking the wheel (per Step 2) is the more reliable way to confirm the joint itself rather than the bearing. If you can't get a clear visual, that's a case for a second opinion rather than guessing.
Step 3: The Pry Bar Test (More Precise Than Rocking by Hand)
For a more direct read than hand-rocking the tire, a pry bar can be positioned between the control arm and the steering knuckle (or in whatever gap your vehicle's geometry allows) and used to apply gentle leverage while you watch the joint directly. Visible movement between the stud and its housing, or a distinct clunk as you apply and release pressure, indicates wear beyond acceptable clearance. This is the same underlying principle as the hand-shake test — checking for play at the joint — but it isolates the joint more directly than rocking the whole tire assembly.
Beyond DIY: Dial Indicator Measurement
For a fully quantified answer instead of a "feels loose / doesn't feel loose" judgment call, a dial indicator can measure actual joint movement in thousandths of an inch and compare it against the manufacturer's spec. This is professional-shop-level precision, not a typical DIY step, but it's worth knowing it exists if a hand-test result comes back ambiguous and you want a definitive number rather than a judgment call.
What a "Pass" Doesn't Tell You
A shake test with no detectable play confirms the joint isn't obviously worn right now — it doesn't confirm the boot is intact, or that the joint won't develop play over the next few thousand miles. The shake test is one part of a full inspection, not a replacement for it. See our full ball joint inspection guide for the visual boot check and the rest of the routine that goes alongside this test.
Related reading: For the complete inspection routine including the visual boot check, see our guide on how to inspect ball joints. For how to tell whether it's the upper or lower joint that's worn once you've confirmed play, see our upper-vs-lower ball joint guide. For how urgent replacement is once you've confirmed a bad joint, see our ball joint lifespan and urgency guide.
