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Old 04-12-2011, 04:03 AM   #1
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Adjustable control arms

I recently purchased some adjustable control arms for the upper front of my jeep. I was wondering if anyone know how much I need to adjust I have a 4" lift.

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Old 04-12-2011, 08:49 AM   #2
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you don't need adjustable uppers in front. and even if you have them you want to keep them at stock length. if you can, you might even shorten them 1/4". the stock length is 15" eye to eye in front.

to adjust caster you want to make the front lowers longer. you want ~5° caster with 35s, ~6° with 33s.

if you push the uppers out you run the risk of pushing the track bar into the diff cover at full bump, and/or causing binding in the steering linkages.

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Old 04-12-2011, 08:46 PM   #3
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Thanks for the input I haven't purchased the rear upper adjustable control arms yet is it the same case for the rear also?
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Old 04-12-2011, 09:00 PM   #4
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Originally Posted by KondritzTJ97 View Post
Thanks for the input I haven't purchased the rear upper adjustable control arms yet is it the same case for the rear also?
no not at all. rear uppers and rear lowers must be adjusted in concert to set pinion angle.

you can't push the rear axle back much because the diff cover will hit the gas tank and the tires will hit the rear of the wheelwell under full compression. so you need to keep the rear lowers at stock length, and extend the uppers as necessary to set pinion angle. ideally, you'd want adjustable uppers and lowers, so you could rotate the axle housing about its center axis, not levering it by adjusting only uppers or only lowers.
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Old 04-12-2011, 09:00 PM   #5
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no. when you lift 4 inches or better you will need at minimum adjustable upper rears.

You will also need a Slip Yoke eliminator and a double cardan driveshaft.

You can squeak by sometimes with a TC drop kit or maybe even a Motor mount kit... But the right way to do it is SYE/CV shaft and adjustable uppers
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Old 05-01-2011, 06:16 PM   #6
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If you lengthen the rear upper control arms to change the pinion angle, the entire axle rotates to achieve this new angle. Is that what's happening in this scenario? If so, do you have to relocate shock mounts and spring perchs to this new orientation? It seems like these things would be negatively affected.
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Old 05-01-2011, 08:40 PM   #7
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Originally Posted by umphreysfan View Post
If you lengthen the rear upper control arms to change the pinion angle, the entire axle rotates to achieve this new angle. Is that what's happening in this scenario? If so, do you have to relocate shock mounts and spring perchs to this new orientation? It seems like these things would be negatively affected.
Yes, the shocks can definitely be an issue. So can the springs. Most don't do anything with the springs, but shock relocation is pretty important. Companies make the springs pretty stiff in the rear to compensate for the curvature that results from the altered pinion angle and increased height.

But spring perch relocation and shock relocation are popular mods to fix the geometry.

Read these:
Outboarding rear shocks AND upper spring bucket relocation - JeepForum.com
low lift, long shocks, and DIY shock shifters... what's the advantage? - JeepForum.com
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Old 05-02-2011, 06:30 AM   #8
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When i rotated my rear the shocks were the only issue i had, the lower spring pad is at a slight angle over stock, but nothing you should be about with only 4" of lift imo. The problem that I personally ran into was my shocks hitting the perch when the axle drooped. I looked into the possible solutions which were:

1. invert shocks so canisters on top (Makes no difference with OME shocks so that was a no

2. Lower shock mount relocation (looked at a few brands, none of them seemed trustworthy as a bolt on solution, if you take this route i would definitely reinforce and weld)

3. Trim the perches (ended up taking this route, only took off about 3/8 at most but at full rear flex i don't have any interference, and it took 5 mins with cut-off wheel
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Old 05-02-2011, 10:20 PM   #9
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I took the same route a couple of weekends ago and ground into the perches. I just bumped up to 4-5" and had some RE lower mounts welded wrong in a bad position, so I took about 1/2" off of each perch and really should have gone another 1/4" to 3/8ish".

Got a question, sorry to jump in on this link. Sorry for the long version of the question.
As the springs sit, the driver side has room for the shock with the coil oriented as is, so I could grind some more. On the passenger side the beginning of the coil "wrap" is oriented so grinding more off wouldn't help much because the shock body would start to hit the spring. So I was thinking since the springs probable spin around some during articulation. I should be able to orient them for the best clearance and attach some spring clamps on the lower perches somewhere? Anyway am I not thinking something through? Also thinking during spring compression whatever I do, the springs will get closer to the shock body as they seat??
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Old 05-08-2012, 11:00 AM   #10
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Long story short, i'm going back to 3in from 4in. I curretnly have fixed LCAs all around. will these be to long for the difference in height?

My stock control arms are history and I dont really want to use them.

David
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Old 05-08-2012, 11:07 AM   #11
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Originally Posted by david95xj View Post
Long story short, i'm going back to 3in from 4in. I curretnly have fixed LCAs all around. will these be to long for the difference in height?

My stock control arms are history and I dont really want to use them.

David
how do you know the fixed length LCA's will keep pinion angle, caster and axle position correct?

you don't...that's why fixed length arms aren't worth a whole lot. get adjustables with Currie Johnny Joints.
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Old 05-08-2012, 11:32 AM   #12
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Unlimited,

I agree i want to get Adj CAs, but at 3in isn't that at the min level of most CA that are suited for larger lifts?

Am I going to be close to factory length at 3ins?
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Old 05-08-2012, 02:16 PM   #13
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Originally Posted by david95xj View Post

I agree i want to get Adj CAs, but at 3in isn't that at the min level of most CA that are suited for larger lifts?
No. You're not thinking about this correctly. Any quality set of off-the-shelf arms will work fine for a TJ with 3" coils and will give you all of the needed adjustment for future changes.
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Old 05-08-2012, 03:25 PM   #14
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Thanks for the advice!
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Old 02-02-2014, 11:22 PM   #15
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Originally Posted by UnlimitedLJ04 View Post
you don't need adjustable uppers in front. and even if you have them you want to keep them at stock length. if you can, you might even shorten them 1/4". the stock length is 15" eye to eye in front.

to adjust caster you want to make the front lowers longer. you want ~5° caster with 35s, ~6° with 33s.

if you push the uppers out you run the risk of pushing the track bar into the diff cover at full bump, and/or causing binding in the steering linkages.
Not to hijack the thread...
So all you need for a 4 inch lift is adjustable rear uppers?

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