Upper or lower?

 

Both of you can, that allows you to position your axle centered in the wheel well. But if you have to choose one, I think uppers are a little cheaper.

 

To be clear, the caster is way low.. Your factory axle has 6° of caster "built" into it. That means that when the pinion angle is 0° then the C's on the end of the axle are leaned back 6°. Caster from the factory is ~4.2°.....the pinion is angled up 1.8° from factory putting the Cs at a 4.2° lean if that makes sense (it's a fixed relationship). Anyhow, when the jeep was lifted the pinion angle increased and the caster by nature of the fixed relationship was decreased. You want to rotate that axle house again, lowering the pinion and thus raising the caster.

You want your caster at least back up over 4°. Most of us modified guys will shoot closer to 5°. You may ask why not just go full boar and get that caster as high as possible, but at some point there are driveline consequences.




For most people control arm brackets are a great option and will actually give you a better ride than adjustable arms. The downside is you lose a bit of ground clearance at the frame rail. If going with adjustable arms and you can't do both uppers and lower, most people will do from lowers which extend the axle forward, thus rotating the pinion down. The "best" method of caster correction can be different for everyone based on their own use.

You want to get that caster back up over 4°. Most of us will shoot closer to 5°. You might ask yourself why not go full boar and get caster as high as possible.....but at some point you run into driveliine issues due to pinion angle.

 

I know Metalcloak likes to do uppers if you can't do a full set, but I've always thought lowers to be a better option for 2 reasons. First, they allow you to extend the wheelbase a bit while rotating the axle whereas the uppers simply rotate it where it sits. Second, you're replacing the lower arms with something that is usually a decent bit beefier than factory and in an area that could see contact with rocks. That's just how I tend to see it at least.

For OPs situation, that is probably a large enough difference to either go brackets or full arms the more I think about it. If you were talking caster being a bit low, like 3.3° or something, easier to cheap out and just do uppers or lowers. 2.6° is pretty dang low. IMO.

 

What about the back?

 

Well, the rear has no bearing on the steering issue that you're experiencing. The point at which people really NEED to do a full set of rear arms usually revolves around tire size, and 37s being the threshold. That is because when you lift 3.5" or more you pull that rear axle in towards the wheel well a good bit (wheelbase shrinks). Usually you still have room to run 35s with a little trimming of pinch seams around the wheel well, but 37s not only get really tight, they start to look more awkward where the tire is sitting in relation to the center wheel well.

By all means you can do a full set of arms addressing the rear as well, but it's not required. It's maybe a bit more important with a 2dr's wheelbase, but the 4dr is more accommodating with the driveshaft angle and with that rear DS having CV joints on both ends.

 

Thank you so much, you have been a ton of help.

 

well, I HOPE that getting caster higher helps out the situation....i just can't say with 100% certainty it will. I think at one point in the very early days my caster was around 2.8 and never had that kind of issue, though drivability really improved once corrected. The only times I've had the steering wheel not want to return to center was tight steering after replacing ball joints.

 

I was wondering about the ball joints but the steering system and force of caster making the wheels return to center is so much greater than the rotational force of a ball joint. If a ball joint is causing this then I would think that the ball joints are nearly seized, which isn’t a common issue with ball joints. Typically they get play in them, not lock up.

 

How hard are they to change myself, does the jeep need to be lifted or on the ground?