After installing my lift (3" FT Econo), my JK pulls into ruts.
I know I need to replace my control arms to adjust the caster angle.
Which do I replace? Upper or Lower?

 

Both! you can try just the uppers or the lowers but apparently you are bugged by the flighty steering, If you really want to "dial it in" get both. Talk to Dave at Northridege. I just ordered mine last week. I got the FT arms. they are a bit pricier but they are built for a tank!

 

Which would be better to get? Uppers or lowers?
Any difference?

 

uppers push the top away, lowers pull the bottom in. ideally, you should have both. that failing, i would go with uppers.

your castor may not be the problem. wider tires find ruts easier. my TJ was all over the place. after i worked out all my steering issues. i even find them with my Rubi's little pizza cutters.

 

My YJ had 13.5 wide Mickey's and were really bad. That is until I installed a shackle reversal kit.
That solved the problem. I guess I will go with uppers.
Thanks!

 

Just ordered the Full Traction Upper Adjustable Control Arms from Quadratec. Also ordered the Superlift steering stabilizer to help as well. I will let you know how this turns out.

Another Question:
Do I make the new arms longer or shorter than stock?

 

So you don't have adjustable arms, correct? I have a 4" Skyjacker lift and I don't have adjustable arms either, and I don't have that problem. It's possible part of it could be related to your tire wheel combo. I've noticed my rides different than it did with my previous wheels. How bad's the pull?

 

It has a decent pull. It was pretty bad before I lowered the psi in the tires. I am now running on 25psi, but it still isn't right. It might be the tire/wheel combo - not sure. Hopefully, this fixes it.


Thanks. That makes sense.

 

Buy the upper control arms to set your caster. The lower ones are a waste of money. Jeep uses cams on the upper control arms to adjust caster. But the adjustable upper control arms do the same thing but much stronger.

 

The way I have always looked at it:

The lowers mainly position the axle fore/aft

The uppers allign the axle

When you lift, the axle moves closer to the control attachment point on the frame (even if it is just a little bit). To get it back to where it should be, you extend the lowers.

The uppers will then be used to twist the axle back to it's normal castor angle.

Some people will tell you one, or the other. To really do it right, you need both, but they need to be the right lenght.

Simply said, if you can get adjustable uppers, that is the way I would go.