JKlad

OK, so I'm looking for a simple explanation in layman's terms as to what I'm looking for when diagnosing whether my upper and/or lower ball joints are bad.

I've had some experience with ball joints on older cars before but I understand that the JK's ball joints have a different (and more limited) range of normal operational movement to ball joints commonly used on the upper & lower control arms of car-type independent front suspensions. My warranty's running out soon so I want to get everything possible sorted out at the next service and if the joints are bad, I want to know what I'm talking about to the service manager at the dealership in case he tries to blow me off and says everything is OK.

So from what I understand I jack up the front end, grab a front wheel at the top and bottom and apply pressure to the top & bottom in turn. So firstly, what is the normal range of movement for a healthy JK ball joint (ie: rotational only, lateral, etc)? Then secondly, what exactly am I looking for movement-wise to indicate that the ball joints are bad?

Thanks in advance for your replies!

Ralioth

Wow! No replies yet. Kinda interested myself since I've seen so many threads with "WTF!?! My ball joints are bad!! Boo-hoo!"

OscarTheJeep

Diagnosing bad ball joints on a solid axle vehicle is relatively simple. Jack up the Jeep and place a jack stand under the axle tube to support the vehicle. I always try to place the jack stand right behind the "C's" for stability. Next, grab the top of the tire at the 11 and 1 o'clock positions, then push and pull the tire in and out. (Toward the center of the Jeep). If the top ball joint is bad, you'll feel it.

For the lower ball joint you place your hands at the 5 and 7 o'clock positions and do the same thing, push and pull on the tire. If it's bad, you'll know it. I think it's more common for the lower ball joints to fail than the uppers. It least it was on all the old Chevy's I've owned.

ronjenx

The upper ball joint is checked for side play.
The lower ball joints are checked for vertical play.

Here are the limits:

Radial (side-to-side) movement in the upper ball joint should not exceed 0.060" (1.5mm).

Axial (up and down) movement in the lower ball joint should not exceed 0.050" (1.25mm).



A dial indicator is the best instrument to measure ball joint play.

Jack the front tire off the ground.
Place a jack stand under the axle next to the jack.
Lower to put some weight on the jack stand.
Place a long pry bar under the tire, from the side.
Have someone pry the tire up and down while you watch the lower ball joint for up and down play.
Axial (up and down) movement in the lower ball joint should not exceed 0.050"

Have someone grab the tire at top and bottom to wiggle the top in and out while you watch the upper joint for side play.
Radial (side-to-side) movement in the upper ball joint should not exceed 0.060"

Even if the upper joint checks good, change both if the lower checks bad.

SLVR07

I am the original owner of my 07 JK with 25K. It is a daily driver and the lower ball joints were shot. It has 33's (285/70/17), swaybar disconnects, 2.5" BB and has been wheeled with care occasionaly on moderate to easy trails. I realized I had some play in the lower joints; but when I took it appart they were extremely loose. I now have Dynatrac uppers and lowers, I hope this solved the u joint weak link issue.

Techvibe

diagnosis:
-put the Jeep on jackstand, wheels 2 inches off the ground.
-use a long bar (3 to 5 feet) and put under the tire.
-have someone lift it while you watch the ball joint.
-if there is ANY play up and down, it's dead.

-

Jay2013jk

In PA 1.5mm movement fails Inspection.. My JKU 2013 56K miles was at 1.0 mm. Ok for now.. No Wobble either.. BTW have run 33's on 17x9 Pro Comp wheels for years its a DD.