what length should the upper and lower control arms at 4.5 inches of lift - JeepForum.com
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Unread 11-10-2013, 01:40 AM   #1
97ZJ_FOORx4
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what length should the upper and lower control arms at 4.5 inches of lift

I started my lift today and ran into a problem. my lift from iro doesnt tell how long the control arms should be adjusted to, I mean it gives tells me to find the 18 and 5/16 lower control arm and install. Is this number how far it should be adjusted to center to center or what? it also says install upper control arms, since mine are adjustable what length should i put them at? for the front and rear.

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Unread 11-10-2013, 07:38 AM   #2
OverlandZJ
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The length IRO gave you for the lowers is eye to eye... center of bolt hole to bolt hole.

Coil springs and vehicle weights are not uniform and you need to adjust the uppers for proper pinion angle. You'll need an angle finder for this, Sears Hardware has these for ~$10.

Google image Pinion angle if your unfamiliar, you'll see plenty of diagrams on how to adjust for both a cardan joint (SYE style) or OEM 2 joint driveshafts.
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Unread 11-10-2013, 07:42 AM   #3
Technohead
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The lowers should be the same length as the stock control arms. The uppers should be adjusted to dial in the rear pinion angle and the front caster angle.
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Unread 11-10-2013, 01:33 PM   #4
97ZJ_FOORx4
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Is there a specific length I need to adjust the uppers and lowers to? I figured you would keep the uppers stock and adjust the lowers according to the lift. But you guys say otherwise. The installation instructions just say to install upper control arms. The length of both upper and lowers are crucial to the drivability of the vehicle and I don't see why Iro would leave that information out.
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Unread 11-10-2013, 01:38 PM   #5
WhiteOut
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Because there is no universal control arm length. They need to be adjusted to your Jeep and how it reacts to the lift.
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Unread 11-11-2013, 12:56 AM   #6
97ZJ_FOORx4
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So the adjustable ca's help with the pinion angle, right now I have the lowers extended to 18 and 5/16 from center to center on the rear and the uppers are adjusted to stock length. Should I move them out? It looks like the axle isn't out far enough to clear my tires and it would rub the front of the rear fender wells near the rocker arms.
Is there a chart I can go off from or somebody who runs the adjustys that works and what length are they using? I plan on running 33s.
Or should the axle just be centered in the wheel well?
Or is this something an alignment would take care of?
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Unread 11-11-2013, 02:14 AM   #7
Kodiak17
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Pinion angle is most important. Then caster. Then axle placement. Find a happy balance between all 3. To push the axle back, extend both arm lengths equally.
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Unread 11-11-2013, 03:50 AM   #8
Technohead
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But pushing the axle back on short arms with the factory bracket locations is not recommended. The factory CA lengths will place the axle in the center of the wheel opening at full bump:





Also, I would say pinion angle is most important on the rear. Too little caster is a very common source of death wobble.
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Unread 11-11-2013, 04:46 AM   #9
97ZJ_FOORx4
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So would factory length ca's work and then I just adjust the upper for the pinion angle correct?
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