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Hi I am installing a Rock Krawler 3.5 X Factor on my 2015 JKU I got the front done and now working on the back. The rear lower control arms starting length 20 3/4” the problem is the the arm is way longer than that the front lowers starting length is 23 1/8”. I think it is a miss print but can’t find any where on the web for answers. And I can’t call RK till Monday has any one come by this problem any help would be great
Thanks
 

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First off rears and fronts are not equal lengths. More important, those numbers are just a convenience thing to get you close.

Take your old control arm and use bolts to make same length.

Final control arm length is a RESULT of a proper alignment. A proper alignment of an axle doesn’t care about actual control arm length. You don’t move the axle to accommodate the arms, hence the adjustability. Every Jeep and lift is theoretically different (imperfection of axle and frame bracket positioning and fabrication, exact resulting spring height, etc).

You want the length that will allow you to get bolts in and retain close to the same pinion angle as when you started.
 

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Hi I am installing a Rock Krawler 3.5 X Factor on my 2015 JKU I got the front done and now working on the back. The rear lower control arms starting length 20 3/4” the problem is the the arm is way longer than that the front lowers starting length is 23 1/8”. I think it is a miss print but can’t find any where on the web for answers. And I can’t call RK till Monday has any one come by this problem any help would be great
Thanks
I installed the same lift on my 15' JKUR. I followed their suggested lengths. Triple checked each arm before installing. Each jeep will be a little different. Tire size also play an important part of arm lengths, especially in the rear. I'm runningn 37s. After installation, I used a forklift on each tire and raised it up, to see what was happening. Check brake and ABS line, parking brake etc. When the rear axle articulates, it rotates up and pushes back. Before full flex, tire was hitting the wheel well. And the rear springs were bending all funky. Front axle was rotated up, pinion angle was too much. After flexing, I would go home, remove arm and adjust length, reinstall. Then make arm on other side the same. I did this 3x over 3 weekends to get my jeep dialed in. I think the rear arms are almost an inch shorter of what RK suggested. Front arms were real close, but had to be adjusted. Now I have no rubbing, both axles have about a 0-1° pinion angle. Bump stops line up, it drives on and offroad awesome.

I also installed a few other items when I did this lift. Full suspension installation is an incredible amount of work and time. And patience. This was my first install, we took our time and triple checked everything. 2 days for the install and then 3 days fine tuning it

Installed in my garage with floor jacks, lift stands and mechanical tools. No air tools, no
cordless tools. Yes, I was sore for days.

BF of last year, I threw my wallet at home depot and ran out with almost every dewalt cordless tool. Had to buy another toolbox I bought so many dewalt tools. Yes, worth every dollar.
 

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