YJ Suspension Kit

New from Skyjacker, these...        read full caption New from Skyjacker, these Monolinear springs for YJ Wranglers are made to offer a smooth ride and great articulation as well as provide a 6-inch lift. Rubber bushings (40 durometer) are installed in the single-leaf springs, while all other bushings included with the system are of the poly variety. Notice how much thicker the tapered springs are in the center.

Perhaps the best way to describe...        read full caption Perhaps the best way to describe what comes with the Monolinear suspension system is to point out what doesn’t—there’s no steering stabilizer. Stainless braided brake hoses, U-bolts, track-bar drop brackets, quick-disconnect antisway-bar links, bumpstop extensions, tow-bar shackles (front), antikickback shackles (rear), Softride Nitro shocks, a drop pitman arm, and more is included as well as, of course, the four single-leaf springs.

Since the Skyjacker monoleaf...        read full caption Since the Skyjacker monoleaf is rated at a relatively low 253 in-lb and made to provide 6 inches of lift, it has a much higher free arch than a stock YJ leaf spring (below). In fact, the Monolinear springs seem to give the same amount of lift as a more involved spring-over conversion.

Installation of the Skyjacker...        read full caption Installation of the Skyjacker kit is basically identical to bolting on any YJ leaf-spring suspension. Since our test vehicle was quite modified already, several areas differed from a normal install—hence no step-by-step. Notice that since the spring bushings are rubber, only the upper bolt has a zerk fitting for lubing the poly bushing in the frame end.

Even with the included tow...        read full caption Even with the included tow shackles being 3/4 inch longer than stock, they could barely accommodate these long, super-flexy springs. With the spring compressed (flat, actually), the shackle just touches this Currie bumper. In other words, it’s perfect. For max droop, even these shackles are a bit short.

A 33x12.50 stuffs into the...        read full caption A 33x12.50 stuffs into the fender nicely with the supple Skyjacker springs. The included, longer Softride Nitro shocks with nice, soft bushings allow better droop and help control the friction-free suspension.

While this vehicle was limited...        read full caption While this vehicle was limited by shocks that were too short (because of prior mods), the tweakability and smooth ride of the Skyjacker Monolinear springs were impressive. We expected the springs to settle a bit and had wondered about the long-term durability of a single-leaf. Yet after a week of use and abuse, they were holding steady at the exact same height as when new. And, yes, those U-bolts we used still need to be cut.

Leaf springs are simple and durable devices, but the more complex coil and torsion-bar suspension offer movement free of friction, providing a smoother ride. In an attempt to incorporate the best of both types of springs, Skyjacker recently introduced the Monolinear YJ suspension. The complete system includes everything from bracketry, a pitman arm, shocks, and brake hoses to Rock Ready greaseable shackles. However, it’s the single-leaf springs that are the real news.

FIGHTING FRICTION AND OTHER EVILS
Perhaps the foremost quality of a monoleaf spring is that there’s no inter-leaf friction to hamper movement. Just like a coil spring, the single leaf can react to even minute irregularities on the trail without first having to overcome the friction generally present in a pack of leaf springs.

Also increasing ride quality is the low weight of a monoleaf. At least half of a leaf spring’s weight is unsprung (not supported by the suspension), and unsprung weight is the worst kind when it comes to making a suspension perform and a vehicle handle well.

Aside from potentially large improvements in ride quality, the single-leaf suspension also offers better ground clearance. Skyjacker’s Monolinear springs are only ½-inch thick where they pass under the axle, so valuable clearance can be gained compared to a common, thick spring pack.

AN ALTERNATIVE TO SPRING-OVER
With 6 inches of advertised lift compared to stock, the Skyjacker Monolinear springs provide about the same amount of lift as a spring-over conversion but without most of the inherent hassles. For example, while bumpsteer is increased due to the steeper angle of the drag link, at least there’s no physical contact at hard right turns between the spring and the drag link, as commonly occurs with spring-overs.

Spring wrap is another common drawback with spring-overs and, generally, with single-leaf suspension. However, Skyjacker’s Monolinear springs are tapered (the centersection is thick, with the leaf being much thinner toward the spring’s eyes) in an effort to quench wrap.

A DIFFERENT APPROACH
The fact that monoleaf suspension, with its many good traits, isn’t more common is largely due to production cost. It can be easier and less expensive to engineer and manufacture a spring pack in which several leaves work together to provide certain ride and load-carrying requirements than it is to make a single-leaf perform the same. Luckily, Skyjacker still decided to produce the Monolinear suspension, so now YJ Wrangler owners (and those who have or wish to swap in YJ springs) have another promising choice in compliant suspension.

With a relatively low spring rate of 253 in-lb and void of inter-leaf friction, the Monolinear springs provide a very smooth ride. Yet, even with the tires starting from 6 inches farther below the fenders than stock, the pliant monoleaf springs still allow stuffing the tires all the way back up in the fenders for great articulation.

If we ask nicely, in time, we may see Skyjacker also offer the Monolinear springs for Jeep CJs as well as other four-wheel-drives. Based on how the Wrangler YJ springs shown here have performed so far, we sure would like to see that happen.