so I tried to install my new JKS Adj Rear Upper CA's last weekend, only to find out I couldnt make them any shorter than my OEM Upper Rear CA's. With my TF 2.5" coil lift, right now, my drive line angle looks to measure out right around 6degrees and eyeballing it, looks spot on. I assumed I wanted to make them a little shorter because of not installing Rear LCA's yet, but even at the shortest, the JKS ones were 1/4" longer than stock. By adding 1/4" or more length, that seems like it would have made my rear castor even worse, is that correct? With out changing the rear lowers, i want a shorter than OEM Upper CA length right?

Must i get rear lowers to properly install Rear Uppers?

 

From my understanding, when doing the rear, you want to focus on making sure your pinion angle is the same as your drive shaft angle. Look at some of the flex arm writeups from WOL, he can explain much better than I can.

 

You don't really need adj rear uppers with a stock driveshaft. You will need them to adjust pinion angle with a double carden aftermarket shaft. As you would lenthen them to rotate your pinion up to point towards the T- case flange or yolk.

 

I put Front Lowers on, and it smoothed out the ride alot (even though my caster is still a little less then 4degree, so I can go a little more), would it be worth while to sell/return my rear uppers and get front uppers to go with my front lowers? or does that, with my current set up, really not add anything?

EDIT... Basically, i just trying to figure out what to do with my rears since I cant seem to use them with my current set up. I could buy rear lowers, and move the axle back some and then use the rear uppers at their shortest, but is that really worth it (these things are pricey).

 

My understanding is that if plan to buy control arms... the first 2 sets you should buy are front lowers and rear uppers.

We have all 8 JKS arms and they made the ride quality in our JK 1000x better....

 

This is my understanding as well, which is why i did it, but it doesnt seem to work in the rear without the lower... Just the front Lower was a Tremendous improvement. I am just confused....and upset

 

You could put the rear uppers on anyway at the stock setting. That way if you change the rear drive shaft to a double carden, you'll be ready to be able set the pinion for an aftermarket shaft. Typically, when adding a lift, people will get the frt lowers for castor, if they change both driveshafts , they get rear uppers aswell as a minimum. Since you have a 4dr, you probably won't NEED a rear driveshaft for a long time.The 2drs have a more extreme angle front and rear on being lifted, they are the ones that seem to have to change both shafts pretty quickly. Unless you bash it on a rock and want something more heavy duty, or something easier to fix on the trail, your rear stock shaft with 2.5in coil lift will be just fine on a 4dr.

 

That makes sense.. Even if I go up to TF 3" Coils (which is my plan), i wouldnt need to replace my rear drive shaft, just my front. So i really dont know what to do with my JKS... Sell them, or just hold onto them untill i get rear lowers (and even then, do I really need rear lowers?)

 

I have 38,000 m on my stock rear shaft. 8,000 at stock height, the rest lifted and offroad once a month. I've been lucky not to bash it on anything yet.