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JKS Adjustable Control Arms

Tony Curless | Writer
Posted October 30, 2006
Photographers: Michael Slade, David Conover

An Inside Look

Control arm selection can be a daunting task for any coil-sprung Jeep owner as the number of choices available today is overwhelming. The fact that so many control arms are nearly identical in appearance only makes the decision more confusing. In many cases, we simply cannot make an informed choice without examining the product's internal design and construction.

"So just how can I see inside a control arm?" you ask?

We're going to make it easy for you with an exclusive look at the JKS Adjustable Control Arm - from the inside out!

The importance of a properly engineered control arm is often overlooked when shopping for a new suspension system. Although the correct spring and shock specifications are paramount to the performance of your newly suspended Jeep, an inferior set of control arms can leave you with feelings of lift-kit remorse. To better understand why control arm design is such an important factor, we must look at the role this part plays in the Jeep suspension system.

Control Arm Function
A combination of upper and lower control arms links the axlehousing to the chassis using bushings at each end to accommodate suspension movement. As the suspension compresses and extends, the control arms literally control the position of the axle relative to the chassis. At factory ride height, the operating angles of the control arms remain relatively parallel with the ground; however, as ride height increases, so do the operating angles. This exposes the control arms to much greater forces because they are no longer able to deflect impacts as efficiently.

The decrease in deflection efficiency is more prevalent on the front suspension. With the control arms mounted to the chassis behind the axle, they actually force the tires into an obstacle before deflecting the impact to the springs and shocks. This can transfer a considerable amount of noise and vibration into the vehicle cabin. The problem is most noticeable on Jeep models that have a unibody chassis, since they don't benefit from an additional set of rubber isolator mounts between the body and chassis.

Overview of Adjustable Control Arms
If you own a coil-suspended Jeep, you may already be familiar with the advantages of adjustable control arms. For instance, camber and pinion angles can be changed by simply adjusting the upper or lower control arm lengths independently. Adjust the upper and lower arms together and you can move the entire axle assembly fore and aft - this is particularly advantageous on vehicles with large tires and limited space for them to move within the wheel openings. Some adjustable control arms even rotate during normal operation to accommodate suspension articulation. It is important to note that the methods by which these functions are achieved can vary considerably.

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