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Rock Krawler x-factor arms Install

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44K views 264 replies 22 participants last post by  kjeeper10  
#1 · (Edited)
RK's normal x-factor control arms move the rear axle back over 1" In some cases this can cause a few issues if the installer or xxx shop did not set them up correctly. The swaybar needs to be moved back 1"to clear the bump stops and UCA mounts. A wider bodied shock can come in contact with the track bar bracket. Bowed coils. 2 doors will have more issues because of pinion correction.
I did not want to move the axle back 1", just enough to center the axles in the wheel wells. Lifted 3.5" only requires maybe .5 over stock on the lowers.

RK has 2 part numbers for rear lower CA's. One short (run with stock uppers) and 1 set of uppers (longer and run with the longer lowers) This year RK is releasing a shorter set of rear uppers to be run with the shorter lowers.

RK will also custom cut any arm length you want. I wanted at least .5 on my rear lowers, and enough to set pinion with the uppers. You'll see even .5 the coils have s slight slant and the links contact.

I thought I'd try to clear the confusion when choosing RK arms. Of coarse RK's been great and always willing to help if you call.

Pics below
 
#2 · (Edited)
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#3 · (Edited)
another important note. Understand yourself or whoever is installing the control arms. The arm lengths given in the instruction manual are only a starting point. The same set up may not work for two people. RK recommends a professional alignment after initial or baseline settings. This goes for any manufacture, not just RK
 
#4 ·
#5 ·
Now you're just rubbing it in... ;)
 
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#8 ·
A slight bow or slant is not going to cause any problems. My coils are not too bad but my axle is only moved back 1/2. If you're installing the Standard size X factor arms, relocating the perches , or installing a set of JKS adjustable perches Is a better route to take.
 
#11 ·
Good luck :)


kirkelli said:
Good points and suggestions. Setting up your lift 'right' is the biggest battle for a happy experienc with your JK.... Amen
Click to expand...
Yep
 
#12 ·
Alignment today. I'll share my results good or bad .
 
#15 ·
I posted In my build also. The alignment did not happen. The shop did not have the deep well attachments to mount the alignment heads.
 
#13 ·
Great info!! Glad to hear there'll be an option of uppers for me to compliment my max travel lowers if I have any issues down the road
 
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#14 ·
Exactly .. I believe the max rear lowers will go 1/4-3/8 max over stock for wheelbase. Add upper and you're golden.
 
#16 ·
Ken, I was looking to upgrade or change all the hardware needed for the control arms. I looked up Northridge and what they had but with the discount I get at Fastenal I just decided to piece my own together. Any ways the 9/16 and 14mm don't seem to fit through My front uppers (adjustable side) do you happen to know the bolt size? I'd just bring the arm up there with me but I left in a rush and forgot.
 
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#17 ·
12mm (1/2 won't fit)

Lowers all = 14mm or 9/16

Rear uppers 14mm only.
 
#19 ·
I think i have like 50 zerks now. When we grease these are we suppose to pull the allen keys to prevent to much grease? I know they don't require much maintenance but i was curious about the keys.
 
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#20 ·
The allen keys hold the retaining rings in place.
From what i see, these joints wont take much grease new.
 
#21 ·
yup that would make sense. I noticed the control arms allow very little extension in the front. I had to shorten them from RK spec to get the end links off the front springs. The end links i have shortened as far as though go and they seem a bit tall look at the pic i posted.



does this seem right? eventually i will go to JKS seeing this but figured i'd give these a go since they came in the kit.
 
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#22 ·
jwalters2522 said:
yup that would make sense. I noticed the control arms allow very little extension in the front. I had to shorten them from RK spec to get the end links off the front springs. The end links i have shortened as far as though go and they seem a bit tall look at the pic i posted. does this seem right? eventually i will go to JKS seeing this but figured i'd give these a go since they came in the kit.
Click to expand...
How tall is your lift ?
 
#23 ·
The front uppers go down to 19 1/4 min. So sucking in the lowers is going to lower caster.
I have mine set to 19 1/4 upper and 23 1/4 lower.
 
#26 ·
I have the RK xfactor 3.5 mid arm on a 2013 JKUR. I had the front driveshaft done at the same time as lift. I just got it re geared to 5.13 reputable shop, and at about 60mph and above a very severe vibration. I'm taking it to the alignment shop tomorrow so I'm hoping they can fix it. I thought at first it was the front but as I look at the rear DS which is stock, it looks off and feels like where the sound is coming from, I'm gonna post a pic. Can you maybe tell me if this looks right? Thanks!
 

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#27 ·
Pinion angle looks good plus you have a 4 door and stock shafts are not known to vibe.
Looks like theres gear oil around the pinion output
Feel for any play there in the shaft.
 
#31 ·
I'm about to install the RC 3.5" X-factor lift and after reading ur post kjeeper should I be considering the JKS adjustable perches or will the wedges that come with the lift suffice for the rear springs?

I want it done right the first time...
 
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#33 ·
harv3589 said:
I'm about to install the RC 3.5" X-factor lift and after reading ur post kjeeper should I be considering the JKS adjustable perches or will the wedges that come with the lift suffice for the rear springs? I want it done right the first time...
Click to expand...
Hard to say i have a 2 door. Pretty sure the wedges will work out fine.
 
#40 ·
A lot?

Man .. Going by the pics i would bring the uppers in a turn and lowers out a turn. Will see what the alignment shows. Different arm lengths can put a bind on the axle/mounts.
 
#59 ·
My god you should have 0 vibes.

RK's arm settings will net low caster. I moved my front lowers out 3/16 and uppers in 1/8.
 
#58 ·
I got the 37s coming this week, so then i will know more. I also have a cold air intake so its kinda hard for me to discern sounds. tonight im gonna go up the highway a bit and get a feeling for and driveshaft issues, i look at it like this, if i superchip after the 37s and have and sounds ill just upgrade the driveshaft to take out the last little bit. What do you think?
 
#83 ·
:thumb:
 
B
#87 ·
Stop, take a breath, don't drop it off at any more shops until you have a clear and concise plan.

Step 1: Calibrate for the gears/tires. The reason your transmission is shifting weird is because your Jeep doesn't know it has 37" tires now so it's thinking your old 32" tires are REALLY REALLY heavy all of a sudden. You'll need a tuner. AEV or Superchips seem to be the most popular. Calibrate for your tire and gearing sizes and then see how it drives. Eliminate ONLY this variable first.

Step 2: If you still aren't satisfied, add caster. KJeeper has already explained how to do this earlier in this thread. If you aren't comfortable tackling this on your own, have a shop do it. No need for a digital alignment or any of that jazz; just go in and tell them you want your control arms adjusted for 2 more degrees of caster.

Step 3: If you are still battling a vibration, check your tires. Ensure they are all inflated to the same pressure. Ensure none have slung a weight. Go back to your installer and have them high speed balance them again. Since the issue started before you installed the 37's, this isn't likely to do anything for the vibration but it's the scientific method; eliminate variables.

Step 4: Once you have verified tire pressure and balance, 4-5deg caster, and had all bolts from the lift and steering rechecked for proper torque, then disconnect your front drive shaft and go for a drive. It's ok; you can drive it without a front shaft. If the vibration is gone, replace the shaft. If it's still there, reinstall the driveshaft, take a friend (or 2 or 3, at different times so they don't piggyback on each other) for a drive and ask them what they hear. Don't point it out to them, just ask them if they hear anything out of the ordinary and, if so, to describe to you the circumstances and what it sounds like. This will help ensure you aren't just hyper sensitive and hearing wind noise or the like. Then post back up here with the results. I'd suspect, if you get to this point, that you might have gotten a noisy set of gears or a u-joint going bad in the rear shaft.
 
#88 ·
Thanks, I needed that! So, after thinking about what you said here and kjeepers comments, I used a angle finder app and set it on top of upper ball joint, I got *2, at flange at DS pinion I got*4. So that's my vibration. So, I would need to adjust the upper control arms correct? Should I pull them in out push wheels out? Thanks.
 
#91 ·
Yep !!
 
#96 ·
Sucks the RK uppers wont adjust stock. I would say set the lowers to 23 1/4, hold pinion at 2 and install the uppers. You are forced to go longer on the lower (23 3/8- 23 1/2) just to get caster high enough.
I started at 23 3/8 lower and 19 1/4 upper and was at the same 2° caster. Instead of moving the lowers out i went with shorter uppers to raise caster.
 
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