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Piecing together 3.5" RK Flex system

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Old Jan 3, 2014 | 06:48 PM
  #1  
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I have decided to finally pull the trigger and finally lift the JKU. I'm going to be piecing together a RK 3.5" flex system essentially, but with different brake lines and sway bar discos. Was wondering if I was missing anything. Just fora. Background I have a 2008 JKU 6 speed, front Smittybilt SRC bumper with winch and steel cable (pretty heavy front end) and running 33's at the moment. Everything is currently stock.

What I'm getting for the lift:
3.5" progressive coils.
JKS sway bar discos (haven't decided on rear sway bar links. Suggestions?)
Crown performance 5 layer brake lines 4.5"-6" lift??
Front and rear adj track bars.
Front and rear adj LCA's.
Bilstein 5100's I

will be running my 33's until I need new tires, then going to run 35's. I haven't decided if I am going to go with RK adj track bars or not yet. Maybe someone can give me some suggestions. Also I would assume that going with 4.5"-6" brake lines would still work with only 3.5" of lift? Also has anyone used these crown performance brake lines? Now I guess my biggest concern is will I have to get a new front drives shaft? According to RK website it says it is recommended for 2012 and newer but not required. Also would I have to get a high steering kit, or isn't that really needed? I was planning on replacing my steering stabilizer, I mean it has 90k miles on it now.

If anyone has any input or suggestions, it's greatly appreciated. -Blair
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Old Jan 3, 2014 | 10:10 PM
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This kit now comes from RK with their new triple rate coils. Might want to look into that and see if you would rather these then the progressive coils.
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Old Jan 4, 2014 | 02:59 AM
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Default Piecing together 3.5" RK Flex system

Yep triple rates now.
At 3.5 you will want track bars. A rear TB raised bracket (Teraflex has a nice bolt on)

Front lower CA's (caster)
If you are sticking with RK, they offer two different Length rear lowers. Usually I recommend uppers -if only running one set for pinion angle. The RK uppers are designed to work with their longer lowers and move the axle back 1"
Another option, if you want to run their shorter lowers, but want to retain (running uppers), call and request the uppers shortened.
Honestly, moving the axle back 1" can create other problems and not needed unless running a larger tire

The front DS will go before the rear if you disconnect often off road. You don't have to go and replace right away... Same with the rear.
Come time control arms might be needed to correct angles to run a double carden.
Contact with the exhaust cross over is the biggest concern. That's where exhaust spacers come in. Another option is limit straps.

Brake lines are pretty long on a JK when disconnected from the frame. Flex out the Jk and see what's needed for lengths

Bumpstops, same. You want to install the shocks and tires you choose and cycle the suspension. Bumpstops are going to protect the shocks and keep the tires away from the fenders
You want to run the least amount needed. That's why they are not included in their kits. No two jeeps will be the same.

Swaybar end links. 10"-11" links should work at 3.5". I believe RK's are adjustable ?
You want the sway bar itself to run parallel or slightly higher at ride height.

Whoever you call to orders parts. Make sure you are getting the latest gen coils and joints. I've heard of people getting leftover older parts.
The triple rate coils and new joints are a nice step up. RK did a good job IMO

Last edited by kjeeper10; Jan 4, 2014 at 03:05 AM.
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Old Jan 4, 2014 | 03:02 AM
  #4  
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Also -

Highsteer kit - these kits correct angles for any bumpsteer. Def run the lift for a while. You may not even need it.
Note: 3" bumpstop or notching the frame is recommended for clearances.

Stabilizer- never a bad idea running bigger tires.
I would look into at least raising it over the tie rod.
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Old Jan 4, 2014 | 04:13 AM
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I just installed the crown performance brake lines on my rig with a RK 2.5 and the install was simple and everything was included. Very strait forward. I went longer then needed as well, I think mine were made 4" longer then stock but work great on my 2.5.
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Old Jan 4, 2014 | 08:21 AM
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I would skip the rear trackbar and just go with the relocaction bracket. Its really not off center enough to worry about it. Save some money or use it to get the pro tie rod, that is if you plan to wheel it. If not just stick with the stock tr.
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Old Jan 4, 2014 | 09:35 AM
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^ you are right. Using the 2nd hole in my raised bracket, the axle is slightly over corrected. The RK track bar I'm using is shorter than stock.

Same can say for the front running a Highsteer kit. I still like the idea of a stronger aftermarket TB w/ a perfectly centered axle up front.
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Old Jan 4, 2014 | 11:46 AM
  #8  
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Originally Posted by kjeeper10
Yep triple rates now. At 3.5 you will want track bars. A rear TB raised bracket (Teraflex has a nice bolt on) Front lower CA's (caster) If you are sticking with RK, they offer two different Length rear lowers. Usually I recommend uppers -if only running one set for pinion angle. The RK uppers are designed to work with their longer lowers and move the axle back 1" Another option, if you want to run their shorter lowers, but want to retain (running uppers), call and request the uppers shortened. Honestly, moving the axle back 1" can create other problems and not needed unless running a larger tire The front DS will go before the rear if you disconnect often off road. You don't have to go and replace right away... Same with the rear. Come time control arms might be needed to correct angles to run a double carden. Contact with the exhaust cross over is the biggest concern. That's where exhaust spacers come in. Another option is limit straps. Brake lines are pretty long on a JK when disconnected from the frame. Flex out the Jk and see what's needed for lengths Bumpstops, same. You want to install the shocks and tires you choose and cycle the suspension. Bumpstops are going to protect the shocks and keep the tires away from the fenders You want to run the least amount needed. That's why they are not included in their kits. No two jeeps will be the same. Swaybar end links. 10"-11" links should work at 3.5". I believe RK's are adjustable ? You want the sway bar itself to run parallel or slightly higher at ride height. Whoever you call to orders parts. Make sure you are getting the latest gen coils and joints. I've heard of people getting leftover older parts. The triple rate coils and new joints are a nice step up. RK did a good job IMO
Wow. That's a lot of info lol. Sounds la lot more difficult than I had imagined. I would eventually get uppers as well but was just going to start with lowers since they were in their kit. To be perfectly honest I am by no means an expert on caster. I would like to avoid the possibility of more problems, the easier the better. I do wheel my JK as it it, but only have disconnected once.
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Old Jan 4, 2014 | 03:23 PM
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Haha

Like I said (if I wasn't clear) if you want to eventually run rear uppers. RK will shorten a set to run with the lowers you have.

The front lowers will have adjustment for your caster.
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Old Jan 5, 2014 | 05:11 PM
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Originally Posted by kjeeper10
Haha Like I said (if I wasn't clear) if you want to eventually run rear uppers. RK will shorten a set to run with the lowers you have. The front lowers will have adjustment for your caster.
So then I'll be good with stock DS with the lift and LCA's. Only thing I'm wondering is how hard of a job it is to set my caster. And make sure everything lines up right.
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