On a Jeep Wrangler there are four control arms per axle - two on the bottom (called lower control arms, or LCAs) and two on the top (called upper control arms or UCAs). These control arms connect the frame of the Jeep to the axle in a scissor style, allowing the axle to move up and down as you go over bumps, rocks, etc. On a stock Wrangler, these are simple pressed pieces of metal in a U shape and are what's know as "fixed length" meaning they can't be adjusted longer or shorter.
So, why install new control arms?
The most common reason to install new control arms is to help restore proper suspension geometry after installing a lift. When you install longer springs on your Jeep, the axle is pushed downward, away from the body of the Jeep. Since the lower control arm is a fixed length, it is forced down, and back towards the body of the Jeep. This is like the hands of a clock - when the minute hand is at :20 it's farther to the right than when it moves down to :25. So, to restore the proper axle position (and caster) we'll need to lengthen the lower control arms.
In this photo you can see the stock upper and lower control arms. We'll be unbolting the bolts on each end of the lower control arm, and just replacing it. That's it - two bolts per arm.
![Jeep-Control-Arms.jpg Jeep-Control-Arms.jpg](https://www.jeepz.com/forum/data/attachments/4/4646-24f35120cae4738d971a8ec0c9624f60.jpg)
So, why install new control arms?
The most common reason to install new control arms is to help restore proper suspension geometry after installing a lift. When you install longer springs on your Jeep, the axle is pushed downward, away from the body of the Jeep. Since the lower control arm is a fixed length, it is forced down, and back towards the body of the Jeep. This is like the hands of a clock - when the minute hand is at :20 it's farther to the right than when it moves down to :25. So, to restore the proper axle position (and caster) we'll need to lengthen the lower control arms.
In this photo you can see the stock upper and lower control arms. We'll be unbolting the bolts on each end of the lower control arm, and just replacing it. That's it - two bolts per arm.
![Jeep-Control-Arms.jpg Jeep-Control-Arms.jpg](https://www.jeepz.com/forum/data/attachments/4/4646-24f35120cae4738d971a8ec0c9624f60.jpg)
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