2008 Jeep Wrangler Coilover Suspension - ACOS By JKS

The ACOS bump stop cylinder is charged with 150 psi of nitrogen and installs into the main body of the ACOS cylinder. Nitrogen pressure can be adjusted as desired.

A fat O-ring is installed onto the piston shaft so that you can observe where your suspension has been after the fact. This will help determine final adjustments for the position of the cylinder.

The top of the rear springs seat against a stamped frame bracket. The center of the bracket is enlarged to allow for the diameter of the ACOS cylinder. The bracket is not thick and the grinding only took a few minutes per side.

Six holes are drilled in the frame bracket to mount the ACOS base. The stock bracket is slightly cone shaped making centering of the ACOS bracket a snap.

The aluminum adjustment ring establishes ride height. We started with the support ring adjusted as far up as possible and then worked it downward to get the final lift measurement.

JKS furnishes a new polyurethane spring support that provides the cushion between the top of the spring and the aluminum adjustment ring.

The front ACOS components went together faster than the rear. One quick cut to remove the original bump stop was completed in a matter of minutes.

The main ACOS tube slides over what is left of the stock bump stop tube with a perfect fit.

This is the only welding required for the entire installation. We asked our friend and fellow four-wheeler Derek Snead to stop by for a couple of hours on a Saturday to knock out this step. Setting up the TIG machine took longer than making the actual welds.

Two small TIG welds secure each front ACOS tube in place.

With no other suspension changes, the ACOS kit will produce a minimum lift of 1 inch in the front and 2 inches in the rear. The minimal lift is caused by the thickness of the aluminum adjustment ring combined with the height of the ACOS steel mounting base. The maximum lift achievable from the ACOS system is 2-1/2 inches in the front and 4 inches in the rear.

In stock form, our JK suspension maintained a "nose down" position. In order to avoid using too much of our front ACOS adjustment right away, a set of 2-inch Old Man Emu springs were used up front with stock springs retained in the rear. This combo leveled the Jeep perfectly while maintaining an even amount of ACOS adjustment at each corner.

While discussing our lift plans with Jim at JKS Manufacturing, he informed us that their new line of adjustable control arms for the JK are nearing release. The top control arms shown here are for the front suspension. One key design benefit on all of the new JKS arms is the use of actual JK rubber bushings supplied by Chrysler. The JK arms are completely adjustable with welding and machining qualities typical of the high standards we are accustomed to seeing in JKS products.

Cutting and removing the stock spring perches is a quick and easy task however it is unlikely that they will be salvageable. We chose to discard the old brackets and use these new spring perches from JB Conversions, Inc.. The new JB spring mounts are machined from solid 4140 steel and are milled to fit the axle tube OD perfectly. The new mounts also incorporate a coil retention cap as part of the base.

The amount of lift achieved with the ACOS system and the Old Man Emu front springs worked out to be right at our 3-inch target. Different bumper and winch choices may give a final lift that is different from ours. We did run into one issue that is sure to happen in almost all instances. Rotation of the rearend pinion angle is required when installing a lift on just about any Jeep. The JK is no different. The adjustable control arms found in most lift kits today allow for easy manipulation of the pinion angle however the stock axle spring perches are welded securely in one position. If these perches are not moved or changed, the spring coils will not remain in correct alignment after the pinion angle is set. Notice in the photo how far off the ACOS piston is located with respect to the perch.

Our mild 3-inch lift provided excellent clearance for 35-inch tires. Under full compression there were no issues with rubbing. Achieving a proper wheel offset on a JK often requires the use of spacers. By using the Mickey Thompson Classic II wheels ( part #379431), an offset of 4-1/2 inches was achieved without using spacers. OMF sells the Classic II with bead locks already installed.

We're quite sure that the stock JK drivelines were designed with manufacturing costs in mind. Based on first hand experience, the range of movement on the Chrylser driveline is not favorable when the suspension flexes with a 3-inch lift. Notice the size difference between the stock Rzeppa CV and the Tom Woods CV joint. Tom has taken the conventional Spicer CV joint assembly one step further by improving the ball and socket design for additional strength and sealing capabilities.

The rear flange and 1330 front-end yoke on the 2008 241OR are different from the 2007 model. JB Conversions offers a few high-clearance yoke equipped with the proper counter bores to match the Chrysler O-Ring and elevated output shaft shoulder of the 2008 model.