When you start with nothing you have nothing to lose, but when you start with an old CJ the sky's the limit. Building a Jeep CJ is pretty wide open. Tons of parts are available, and just about everything has been tried before: V-8s, multiple gearboxes, every size tire and axle combo. It's half boring and half challenging to build a Jeep and do something unique. In case you missed the Ultimate CJ last month ("Erod Action"), it was the start of the little Jeep CJ-7 we're building to lead our Ultimate Adventure trip this year. It should be able to run down the highway at speed, crawl over boulders in whatever state we end up in, and still have room for gear, grub, and a couple of people. Last month we stuffed a GM Performance Parts Erod V-8 crate engine in the Jeep. Boring, you say? Only if you think that 400-some horses and a smog-legal engine swap is boring. Yes, it's another Chevy V-8 in a Jeep, but it's a modern V-8 and will be followed by a modern powertrain. This month, however, we move down under for suspension. 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.Devising a suspension system for a street and trail Jeep is like opening a bag of monkeys. 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.The three-link and track bar is a good cross between flexibility for trail use and dependa 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.We also mounted a PSC early Bronco steering box way out in front of the grille on the outs 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.With the forward-mounted steering box and a flat pitman arm, we had proximity for the fram 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.Finding a strong track bar is always an issue with this suspension design, as the track ba 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 upper link of the three-link runs from the driver's side inner framerail to a mount ab 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 linked suspension locates the axles, but it's the 12-inch Fox coilover shocks that pro 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.The rear suspension needs to be flexible yet still control the 430 hp coming from the Erod 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.Our rear springs are BDS Jeep Wagoneer front leaf springs. We worked with BDS to find a ni 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.The front spring mounts are from Poly Performance, but while at Western Fabrication we add 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.Because the springs are so long and we wanted to keep the Jeep relatively low, we had to d 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.The rear shackles actually hang behind the rear bumper, so Western Fab cut them out of 1/4 SOURCES PSC Motorsports 11468 FM 730 South Azle TX 76020 817-270-0102 www.pscmotorsports.com Dynatrac 7392 Count Circle Huntington Beach CA 92647 714-596-4461 www.dynatrac.com Poly Performance 245 Tank Farm Road Units L & M San Luis Obispo CA 93401 805-783-2060 www.polyperformance.com Western Fabricators 9823 E Avenue Hesperia CA 92345 760-949-1441 www.westernfabricators.com GM Performance Parts P.O. Box 33170 Detroit MI 48232 800-577-6888 www.gmperformanceparts.com By Fred Williams Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
