freetors
freetors Reader
1/2/22 1:14 p.m.

I recently picked up a 2014 Jeep JK Wrangler Rubicon. A previous owner installed a 2.5" teraflex lift (which actually came out to closer to 3.5") and 35" tires. I've been working on trying to improve the drivability and stability of it since it wanders around, follows road crowns, and just feels generally unstable. So far I've already found a loose rear panhard bar relocator bracket that I was able to just retighten, the front has about 1/2 toe out on the front (!!!), And the tires were way over inflated. All of this helped a lot but I believe it can be better.

So I was poking around with a pry bar trying to find things were loose and noticed that both left and right steering knuckle had vertical play on the ball joints on the C's, it wasn't a lot of play, maybe .03-06" but it seemed concerning to me. I couldn't detect any lateral play in them though. Now I did some light googling and a lot of people are claiming that is ok and many solid front axle vehicles have this same kind of play even from the factory, but others say that any slop whatsoever is bad. I'm personally more inclined to believe the latter. It seems to me that if the ball joint can move laterally with a little force then there would be nothing stopping it from moving radially with all the forces of driving. Is this analysis correct? The tires did have a lot of camber and toe wear... And there is a visually noticeable amount of camber on the front end, but I haven't put an angle finder to it yet. In the same way the ball joint on the drag link where it connects to the knuckle also has axial play.

So what say you grm, do I need a bunch of new ball joints or am I being too critical.

Run_Away
Run_Away Dork
1/2/22 1:41 p.m.

In my experience those vehicles always have a ton of axial play in the steering joints, it's normal. Brand new joints will show the same, they are spring loaded.

Poor road manners it just a characteristic of those vehicles....

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
1/2/22 3:23 p.m.

Only the lower ball joint locates the knuckle vertically, but yes there should not be that much play.

freetors
freetors Reader
1/2/22 8:18 p.m.

In reply to Pete. (l33t FS) :

Yeah that was my understanding from what I had read elsewhere, that the upper acted as a kingpin and the lower should control its up and down spacing.

 

Maybe I'm being unrealistic with my expectations but the JL I rented a while back drove beautifully, just like a big car. I'd love to be able to get close to that.

One thing I know I need to do is get some adjustable lower control arms to get my caster back in check from the lift.

Eventually I want to get rid of these super heavy mud tires and replace them with the new Goodyear territory tires that come on the new bronco. That and some lighter wheels would shed about 25 pounds per corner!

APEowner
APEowner SuperDork
1/2/22 8:55 p.m.

Getting rid of that toe out will make a huge difference all by itself!  

freetors
freetors Reader
1/2/22 9:23 p.m.

In reply to APEowner :

Oh believe me it did! It went from feeling honestly a little unsafe to decent.

rslifkin
rslifkin UberDork
1/3/22 8:06 a.m.

Unless I've lost my mind, there should be no vertical play at all.  Drive the Jeep down a washboard road.  If you can hear a rattle / clunk or other noise from the front end hammering over the bumps, the ball joints are definitely shot. 

Cooter
Cooter PowerDork
1/3/22 8:24 a.m.

What is the offset on your wheels?

That will greatly contribute to poor tracking and self steering, especially if your caster is out of whack from the lift.   Is it a short arm lift?

Opti
Opti Dork
1/3/22 10:05 a.m.

Its been a while since I looked up specs, but I think on the jeeps they are generally about .050 max

Upper you care about radial movement, its supposed to have axial movement

lower you care about axial

drock25too
drock25too Reader
1/3/22 10:59 a.m.

See if You can find the specifications for the ball joints.  When I was doing alignments, the Hunter spec. books had the specs. for ball joints and the proper way to check them.  I can't remember all of them, but there are different ways to test for different manufacturers.

gearheadE30
gearheadE30 Dork
1/3/22 1:47 p.m.

I think Cooter's got a good point - most aftermarket Jeep wheels have a really low offset that pushes the wheels out, and the result is a pretty darn big scrub radius on the front wheels. The result is usually tramlining, steering instability, pulling under braking, bump steer, that kind of thing - with the higher scrub radius, the tires now have much more leverage over the rest of the steering linkage.

freetors
freetors Reader
1/3/22 6:43 p.m.
gearheadE30 said:

I think Cooter's got a good point - most aftermarket Jeep wheels have a really low offset that pushes the wheels out, and the result is a pretty darn big scrub radius on the front wheels. The result is usually tramlining, steering instability, pulling under braking, bump steer, that kind of thing - with the higher scrub radius, the tires now have much more leverage over the rest of the steering linkage.

You know, that's probably a good factor in it too. I haven't measured the current scrub radius but I wouldn't be surprised if it's substantial. The wheels are a zero offset (or really close). I would like to tuck the tires in the fenders a bit more.

rslifkin
rslifkin UberDork
1/3/22 7:13 p.m.

Keep in mind, you actually have to push the tires out some as you make them taller to keep the same scrub radius (due to SAI moving the target as you raise the knuckle higher off the ground).  So the scrub radius might be bad, but probably not as bad as everyone is imagining. 

freetors
freetors Reader
1/6/22 8:35 p.m.
rslifkin said:

Keep in mind, you actually have to push the tires out some as you make them taller to keep the same scrub radius (due to SAI moving the target as you raise the knuckle higher off the ground).  So the scrub radius might be bad, but probably not as bad as everyone is imagining. 

Well according to the wheel and tire specs I've found for a stock Rubicon and an online scrub radius calculator, my wheels and tires have about 1.5" more scrub radius than the stock. So I'd say that's significant.

One thing I did do is loosen up all the bolts on the front control arms and track rod and bounced it a few times. While I tightened them up I took advantage of the manufacturing tolerances and pushed the bottom of the axle as forward as I could to eek out a little more caster. Now it may be placebo, but it honestly seemed to drive a little better.

rslifkin
rslifkin UberDork
1/7/22 8:48 a.m.

In reply to freetors :

If more caster helps, you can use offset ball joints to tilt the knuckles back for more caster.  Otherwise, even with adjustable control arms, you're limited in how much caster you can get by the front driveshaft. 

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