Looking at getting new control arms, more than likely fixed, but open to adjustable if that’s the hands down best way to go. Looking at Teraflex or JKS. My question is, are uppers a must or can I just go with the lower and be good. Also, upgrading track bars front and rear.
going on 2013 JKU 4 inch lift with 35s.

 

a Full set of adjustable is the way to go. You will fix your caster and pinion angles. At 4" of lift you will be able to restore your wheel base as well and need all the arms for that. You should raise the axle side track bar bracket 4" and look into a drag link flip kit up front to really improve your ride quality.

 

Lots of folks on here with more knowledge than me (Dirtman, ReSharp, etc..). With 4 inches of lift, you'll want adjustable control arms and you'll want all eight. You'll want that for a bunch of reasons. Position your axles, get your caster back in range. Fixed arms won't allow you to get your caster and axle position right for YOUR vesicle when taking the weight of your vehicle into consideration.

i'll throw the requisite PSA in about 4 inches of lift as well. That's a bit past the tipping point for lots of geometry issues to take into consideration. You'll likely need to address steering geometry as your track bar and drag link won't be parallel anymore. Your front drive shaft will eventually need to be replaced as the OEM one won't like that angle.

What's the motivation for 4 inches of lift with 35 inch tires? You can fit 35s under a JKU with as little as 2 inches of lift, flat fenders, and proper bump stop.


EDIT... hahahaha... looks like Dirtman replied as I was typing my response!

 

Thanks guys. Bought it with the lift already on it and 33s that needed replaced. I went with 35s because that’s what I’ve always had on my TJs.

 

Just to add on.....pay attention to the joints each manufacturer uses in their arms. The arm itself is what it is, but the joints do differ. Most of us like the duroflex bushings that Metalcloak uses or the DDB bushings that Synergy uses.

 

I bought Teraflex. They were good for a few years. But now I think they're sagging. I will be installing news ones. If it makes a difference, I did buy the basic package which was like $400. Maybe their pricier kits are better. I will be installing Long Arm kit soon.

 

Not a must-have, but you'll be better off with a full set.

All of the suggestions above are good, but the assumption is that you have 4" coils and nothing else, since no further info was given. (I am at least guessing the previous owner didn't slap on 4" coils with no caster correction or axle centering or whatever...) Just for the bigger picture: You are replacing Cam Bolts that are currently installed? If so, search on Cam Bolt Eliminator if you have not already. It currently has a rear trackbar bracket? (dropped from the frame or raised from the axle?) If there is a front trackbar bracket, is there a Drop Pitman to lower the frame side of the draglink, or is the axle side raised to the top of the knuckle?

 

For 4" of lift, you will want all 8 and adjustable. On my rigs, I have just a teraflex 2" leveling lift, and I run their sport lower fronts. Makes a big difference to the way it handles on the street. any higher than 2" I would go with a full set of adjustable arms to dial in everything.

 

recently got some rancho arms and very happy with them so far. great bang for the buck imo.

 

I just put a 4" lift on my JKU and i purchased the Freedom Off-Road Adjustable Control Arms. the Caster was set at 3.5 and causing massive issues with the death wobble. I wanted to see if anyone knew the length that these adjustable control arms should be set at for get the Caster to about 4.2.