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Old 03-22-2014, 01:36 PM   #1
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Rear upper CA help

I'm in the process of installing RK rear uppers, they are recommending 19" center to center measurement for a 2.5" lift. The factory arms are 17 3/8. Has anyone installed these before using 19" as a starting point?

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Old 03-22-2014, 02:53 PM   #2
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Numbers are general. Disconnect the frame side of both. Get the rear pinion pointed to the transfer case output. I use a floor jack and a 2x4. Get the pinoin where you want it. adjust the arms to fit.

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Old 03-22-2014, 03:01 PM   #3
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RK (at least the X Factor) also lengthens or recommends lengthening the wheelbase by moving the rear axle an inch rearwards. I think they do that mostly to avoid pinch seam contact. I'd rather cut the pinch seam. nwbronco's recommendation seems to be the right one- go with the pinion angle and see where things fall.
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Old 03-22-2014, 03:42 PM   #4
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That's kinda what I was thinking just needed reassurance. Thanks for the help
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Old 03-22-2014, 04:21 PM   #5
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Do you have lowers too?
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Old 03-22-2014, 04:31 PM   #6
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Just on the front, I got the rear uppers to straiten out the rear ds a little
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Old 03-22-2014, 04:39 PM   #7
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But... if you lengthen only the uppers, you will be rotating the axle rearwards. That will give you an epic coil bow, more than what a 2.5 lift by itself will give you. Make sure you get coil wedges. Unless you are planning on cutting and rewelding the perches.
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Old 03-22-2014, 04:47 PM   #8
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From the site or after talking to RK and special ordering a shorter set?

There's only one set of uppers. Only to be used with their longer lowers. (2 sets of lowers)

Those will be too long and even at the shortest setting won't be enough to bring the pinion up.
You do want to lengthen uppers for pinion angle but only a small amount.

You need their longer lowers for the 1" stretch or shorten those arms.
If you have a chop saw the threads are deep enough to shorten them or RK will do it for you.

Ask how I know this
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Old 03-22-2014, 04:50 PM   #9
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From the site

NOTES! (Upper rears)
* Recommend having adjustable lower control arms.


NOTES! (Lowers rear)
RK02022 - Rear Lower Control Arms * Requires Adjustable Rear Uppers
RK02064 - Rear Lower Control Arms * For use with Factory Rear Uppers
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Old 03-22-2014, 04:55 PM   #10
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Lol. Well damn, I guess I'll see a bout cutting these down or just order the lowers which I was already considering. After seeing how good the fronts look the stock rears just bother me...OCD kicking in. Plus if and when I go up a little it will be one issue already covered.
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Old 03-22-2014, 04:57 PM   #11
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Quote:
Originally Posted by kjeeper10 View Post
From the site

NOTES! (Upper rears)
* Recommend having adjustable lower control arms.

NOTES! (Lowers rear)
RK02022 - Rear Lower Control Arms * Requires Adjustable Rear Uppers
RK02064 - Rear Lower Control Arms * For use with Factory Rear Uppers
Wish I would have seen that one. Thanks for the help
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Old 03-22-2014, 05:01 PM   #12
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I agree with HK w/ pushing the axle back. You run into coil bowing (even with wedges) track bar issues. Then you need to move the swaybar back which is not a huge problem. This is meant to keep a 37" tire off the seams.
I would shorten them but eventually get the shorter lowers. Just enough adjustability to center the wheel in the well and move the pinion up a little.
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Old 03-22-2014, 05:23 PM   #13
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I installed Rock Krawler rear uppers RK02028's on my 2 door. I needed to correct the pinion angle. With the stock lower I only needed to spin the joint out a few turns. The pinion now points at the rear output of the transfer case. There is not a lot of bow of the springs.

Which arms did you get?
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Old 03-22-2014, 05:38 PM   #14
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Quote:
Originally Posted by nwbronco View Post
I installed Rock Krawler rear uppers RK02028's on my 2 door. I needed to correct the pinion angle. With the stock lower I only needed to spin the joint out a few turns. The pinion now points at the rear output of the transfer case. There is not a lot of bow of the springs. Which arms did you get?
There's only 1 part #

Proper angle is a couple degrees lower then the DS with a double carden. W/ The stock shaft, don't think it will matter much.

What is your lift height ?

I had these arm but sold them. Way to long for what I wanted to so. Move the pinion up
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Old 03-22-2014, 05:55 PM   #15
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Started out as a 3.5" Rubicon Express lift on my '07 4 Door. Moved it to a '14 2 Door and am now at about 5".

Moved the pinion angle. So I guess I should have said rotated.
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Old 03-22-2014, 06:00 PM   #16
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Quote:
Originally Posted by nwbronco View Post
Started out as a 3.5" Rubicon Express lift on my '07 4 Door. Moved it to a '14 2 Door and am now at about 5". Moved the pinion angle. So I guess I should have said rotated.
Makes sense. You needed quite a bit of arm to rotate the pinion back at the height,

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