I’ve read different things where some people say upper adjustable control arms adjust the caster and others say lower adjustable control arms set the caster, and also have seen a few people that say both uppers and lowers are needed to adjust caster. Which control arms, upper or lower, set the caster?

 

When doing a full set of arms, the lowers adjust axle position and the uppers control the pinion angle. If not doing a full set, most will just the lowers only to push the axle out a bit, which in turn will also lower the pinion angle (increase caster) when no other changes are being made. In the rear, if not doing a full set, the uppers are used to adjust the pinion. Metalcloak is one of very few manufactures that uses the upper arms up front if not doing a full set. If you have a 4dr, most people don't worry about the rear as the CV joints on both ends of the rear DS are very forgiving. I can see how it seems like conflicting information. There are several ways to address caster. If you lift high enough, ideally you just have a full set of arms, but every jeep, and everyone's use and budget, is different.

 

Yep, either can be used to adjust the caster/pinion, so it comes down to preference and specific build (use, budget, lift height, whatever). If you look at prices, front uppers are generally cheaper than lowers. And some folks post about beefier aftermarket lowers holding up better than stock arms when slamming down onto rocks and such.

Front
Lower - longer than stock - push bottom of axle housing forward - lowers pinion - raises caster.
Upper - shorter than stock - pull top of axle housing back - lowers pinion - raises caster.

Rear, it's the opposite
Upper - longer than stock - push top of axle housing back - raises pinion to keep in-line with tcase output.
Lower - shorter than stock - pull bottom of axle housing forward - raises pinion to keep in-line with tcase output.

And as noted, when both sets are installed, you'll use one to center and the other to adjust caster/pinion as needed. This also allows you to move the entire axle forward/backward in the wheel wells, which can get more important with taller lifts.

 

Great answers above. The only thing I'd add is if you'd like more specific advice, filing out your profile so folks can see how you've modded your Jeep, or telling us in the your initial post how you plan to modify your vehicle, can net you more specific answers. That profile info works both ways, BTW: Check each of our profiles and you can see how each of us have modded our Jeeps, which may prove useful in where you'd like to direct a question.

 

that’s a good idea, but I just bought the Jeep and still need to take measurements to figure out what size lift is on it, just looking at it I believe it’s a 2.5”. Everything else appears to be stock other than the shocks, the drop pitman arm (that I have removed and put a stock one on) and it looks like the front lower control arms are aftermarket, not sure if they’re extended length or not, I need to measure those too. I kinda jumped the gun when I made this post, still needing to check all of that, including checking the caster to see if it even needs addressed. Just wanted to get some info if it turns out the caster is off and needs control arms to get the caster right. Was looking at which direction to go since I’ve read so many different things about which arms adjust caster.

 

Drop pitmans are generally used as part of a draglink flip/high steer scenario, and at lift heights over 3". Also included would be a relocation bracket for the trackbar. If a bracket was installed, was it removed at the same time as the drop pitman?

Are the shocks Rough Country, by any chance? (asking because a popular lift that includes a drop pitman and front lowers is the RC 3.5")

 

there was not a relocation bracket for the trackbar. And yes the shocks are Rough Country. I haven’t seen the 3.5” lift that comes with the front lowers, I’ve only seen 3.5” lift that comes with control arm drop brackets. Looks like rough country’s 2.5” lift only comes with springs and shocks, that’s one reason I was assuming it’s the 2.5” lift. Figured the drop pitman and lower control arms were add ons and not included with the lift. I’m going to try to look at it more either today or one day this weekend and get some spring measurements and see if I can get part number off of lower control arms, or at least take a measurement of the LCA’s

 

The kit with brackets is the current incarnation of the lift. Try " Rough Country 3.5" Series II ", I think that was one of the previous versions with arms that is still being sold. And sometime before that it came with cam bolts. Just depends on when it was made.

 

good to know, thanks for the info. Just looked again and took measurements and it’s definitely the 3.5” lift with lower arms. Caster shouldn’t be a problem. I used an angle finder and the pinion angle is 2* which should mean 4* caster which is what it should be? And looking at it more closely, it does have a track bar bracket. I used to have a tj and the track bar bracket for it was on the frame side so that’s initially where I had looked for the bracket not noticing the bracket on the axle side, it blended it so well it didn’t look like a bracket at first. Guess I need to now either put the drop pitman arm back on or order a drag link flip.

 

yes, 4* caster should be acceptable. I'd do a DL flip and keep a factory pitman arm. Those drop pitmans are notorious issues on the jk. I see why they get used on pickup trucks, but this is a different beast.