We've been told the definition of insanity is doing the same thing over and overagain and expecting different results. So in our minds this isn't insanity or rocket science. We're simply applying readily available parts (some of which are used) and ideas from the past that produce good results. At this point it's pretty well known that we like FSJ pickups, even more so if they have short beds, manual transmissions, are smog-exempt, and are ours. But realistically many of these tips and hack tricks can be applied to all FSJs or any Jeep for that matter.
Sometimes bolt-on isn't good or bad, it's your only viable option. This was the case with our '73 J20 pickup. We don't need 20 inches of rock-monster wheel travel so an expensive custom-fabbed suspension was out of the question. The truth of the matter is you really only need a few inches of wheel travel and it's mostly to make your Jeep ride comfortably on the typical trail. Ultimately it's the ground clearance, gearing and traction aides that really get you through a difficult obstacle. Anyway, as you can imagine, there are not a lot of suspension companies chomping at the bit to build lift kits for a 36-year-old truck. We were stoked to find Hell Creek Suspension offered 4-inch lift springs for '63-'73 J-trucks as well as other FSJs.
How's It Work
The factory short leaf spring front suspension design on the '63-'73 J-trucks isn't known for being smooth-riding. Installing Hell Creek's 4-inch lift springs didn't exactly help the cause. However, the 37-inch Goodyear tires on 15-inch wheels did improve the ride of the Jeep. To us, suspension travel is suspension travel regardless of whether it comes from the tires or springs. On-road we've been running the front tires at 25psi and the rears at 20psi. This provides a good balance between acceptable tire wear, traction and a decent ride. We need some sort of steering correction, though. The drag link occasionally makes contact with the passenger-side leaf spring. This caused it to bend while out on a particularly twisty trail. We had to sleeve it with a Hi-Lift Jack handle to finish out the day and get back home. In the rear we need to adjust the pinion angle down about 2-4 degrees to eliminate driveshaft vibration. Also, the stock rear springs are designed for load capacity so they are pretty stiff, but like on the front, the 37-inch tires on 15-inch wheels make it livable for now. Off-road we're able to air down lower than normal thanks to the Champion beadlocks for an even smoother ride. We love the traction that the old Goodyear MT/R has provided in the mud and snow but we wish Goodyear would consider offering the new asymmetrical MT/R Kevlar in 37x12.50R15 flavor. For now it's only available for a 17-inch wheel. If you want them too contact Goodyear and ask for the 15-inch version and maybe Goodyear will make them!