Devising a suspension system for a street and trail Jeep is like opening a bag of monkeys. Anything can happen, but it may not be good. We decided that we would try a mixture of high and low tech. First stop was Poly Performance, where we laid out a three-link and track bar front suspension using parts from Poly's universal three-link kit and its JK Synergy suspension kit.

The three-link and track bar is a good cross between flexibility for trail use and dependable and safe street manners. However, developing any link suspension means a mix of suspension engineering and just trying to fit all the parts in the chassis. We started with lower links of 31-inch length and attached them to the front axletube below centerline.

We also mounted a PSC early Bronco steering box way out in front of the grille on the outside of the framerail. This will get us a longer drag link than the standard steering box location, and it frees up space for us to push the axle forward slightly for additional wheelbase and tire clearance.

With the forward-mounted steering box and a flat pitman arm, we had proximity for the frame end of our track bar. This bar and the draglink should be as close to equal lengths and angles as possible. Note the plate that has been welded to the frame and the bolt holes that have been sleeved through the frame to attach the steering box.

Finding a strong track bar is always an issue with this suspension design, as the track bar sees a lot of loads while locating the axle and body laterally. Unfortunately we couldn't fit a straight track bar easily, but, as luck would have it, a factory Jeep JK Wrangler track bar is the perfect length-and being forged, it is strong even where it bends over the diff cover.

The upper link of the three-link runs from the driver's side inner framerail to a mount above the axlehousing. The axle, a Dynatrac ProRock 44, has a JK-style bushing on top, but since we're using a different style upper joint we fabricated a steel bushing and outer link mount to double-shear the joint. The links are made of 13/4x0.188-inch heat-treated 4130 chromoly.

The linked suspension locates the axles, but it's the 12-inch Fox coilover shocks that provide the support and damping. We gave the front suspension 7 inches of droop and 5 of uptravel for good middle-of-the-road performance. We'll delve more into our shocks in a future story, but we can tell you that the shock mounts are also available from Poly Performance.

The rear suspension needs to be flexible yet still control the 430 hp coming from the Erod LS3 V-8. Most would expect another set of links and coilovers, but we decided a set of leaf springs sprung under the rear axle would work just fine while fulfilling our goals. To set them up, we headed to Western Fabricators in Hesperia, California.

Our rear springs are BDS Jeep Wagoneer front leaf springs. We worked with BDS to find a nice long flexible spring that has an offset center pin, which stretches the wheelbase slightly and should flex well. We may add a military wrap to the springs in the future if they are too flexible. To start, we removed all but the main leaf spring to allow ourselves to see exactly how far the springs will flex.

The front spring mounts are from Poly Performance, but while at Western Fabrication we added side bracing. The mounts are angled to better ramp over obstacles.

Because the springs are so long and we wanted to keep the Jeep relatively low, we had to determine how to get enough shackle length without lifting the Jeep up too high. To do this, Western Fab helped design a rear bumper that incorporates high shackle mounts.

The rear shackles actually hang behind the rear bumper, so Western Fab cut them out of 1/4-inch plate with its laser table. This should make them tough enough for trail abuse. The bumper is simple and will protect the special aluminum tub we'll show you next month.