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.
Up front we simply bolted...
Up front we simply bolted on the Hell Creek 4-inch lift springs. We wanted some good mono-tube shocks so we ordered up a set of Rubicon Express shocks for a lifted XJ (PN RXJ507). The same shock is used at all four corners on this FSJ. The stock brake lines and driveshafts reached just fine even at full droop.
The stock U-bolt assembly...
The stock U-bolt assembly is kinda spooky on '66-'73 J-trucks. We ditched the spindly factory front U-bolts and spring plates for some home-made spring plates and Rubicon Express U-bolts (PN 1220) which allowed us to flip them. This provided more ground clearance and peace of mind.
The extra sidewall of 37-inch...
The extra sidewall of 37-inch radial tires mounted on 15-inch wheels helps to smooth out stiff suspensions. That's one reason we chose the Goodyear 37x12.50R15 MT/R tires and wrapped them on some used and battered 15x10 Champion beadlocks. We test fit some 40-inch tires but any amount of off-road use would have had them rubbing pretty badly even if we had cut off the fender flares. We still think the 40s would fit but you'll need to do a little more trimming than we wanted to. An axle upgrade wouldn't hurt either.
The rear lift was the easiest...
The rear lift was the easiest ever. The '66-'73 J-trucks (and some other FSJs) have tension post-mount shackles, so we flipped them. By unbolting the shocks and drooping the suspension you can use a large prybar to flip the shackle around and down for about 3 inches of lift. It made the truck sit level, it's inexpensive (free), and easy. The pinion angle is a little off but not bad enough to do anything about it just yet.
Our Champion beadlocks have...
Our Champion beadlocks have survived two Jeeps, three sets of tires, over 30,000 hard miles, 10-feet of airtime, and pretty much every trail in the southwest that eats sheetmetal. We decided it was in our best interest to at least replace the Grade 8 beadlock bolts and washers.
We smeared anti-seize on the...
We smeared anti-seize on the threads of the new 5/16-inch bolts and snugged them down lightly in a criss-cross fashion. Then we torqued them to 10 lb-ft in a criss-cross fashion and finally spun them home at 15 lb-ft. It's always best to tighten beadlock bolts a little at a time.
At first we tried to keep...
At first we tried to keep the stock steel fender flares intact by lightly trimming the bottom ends for tire clearance. Ultimately the 37-inch tires still rubbed when the suspension flexed in the dirt. Any more trimming would have just looked silly and butch so we whacked off the flares completely for the needed clearance and a cleaner overall look. An air saw makes quick work of the vintage-metal hacking.
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!