Ok so update on the long travel YJ kit...
At this point I think I all of the components drawn up after several attempts to get all the factory holes to line up. At this point the front of the kit looks like it won’t require any drilling but it will need bumper modification. Minimal cutting of the stock bumper but maybe a little more on some after market bumpers. The front will attach with 5 bolts and use a XJ style shackle. I’m using a shackle I had laying around for mock up. I plan to make a super beefy shackle to include with the kit.
All and all, it looks like you’ll be able to get up to about 11 inches of travel depending on the spring you choose. Unlike shackle reversal, the axle will more forward as it compresses which make running bigger tires possible with less rub. Because of the amount of suspension articulation you’ll get out, it may be necessary to upgrade steering to allow for the extreme angles you’ll be able to achieve with this kit. Likewise, drive shaft slip will be at its limits with a 4 inch lift spring. I have yet to cycle the suspension with 2.5 lift springs.
The adaption kit it’s self adds about 1.5 to 2 inches of lift in addition to the spring height you choose, so a 2.5 YJ spring would be closer to a 4 inch lift.
Some people have asked why not just go spring over axle....
There are just too many cons for spring over. Especially when wheeling hard on lighter weight springs like the roxor has. The biggest one, Axle wrap. Under load the axle will tend to want to spin counter to the rotation of the tires. This bends the springs into an S and allows pinion angle to get all out of wack. A lot of times this breaks the drive shaft and/or universal joints. Also, as the rotational force is transferred some of that energy is stored the spring rather then putting it into the ground. As the energy stored in the spring builds it eventually snaps back. This is what causes axle hop. Axle hop puts stress on every component of the drivetrain. The wheels can literally hop off the ground sending shock back through the ring and pinion, drive shaft, transfer case, transmission, etc. This,combined with the poor pinion angle as the axle wraps normally, leads to catastrophic failure. The lower the gears the easier it is to make this happen.
The only way to do spring over correct (more like a bandaid) on a light spring vehicle is to add a anti wrap bar. These bars either are mounted on a shackle or have a slip yoke to prevent the suspension from binding as it cycles.
You can see the high clearance anti wrap bar I had to make for my samurai. And a picture of the anti wrap kit sold by Ruff Stuff.
These anti wrap bars work well with the correct geometry. They hard link the axle to the frame to reduce/eliminate axle twist.
A huge advantage of spring under is minimal wrap with no extra links and a more stable ride. Really the only disadvantage to spring under is the u bolts and spring hanging down below the axle, taking away grounds clearance.
There are some products like this bottom plate from ruff stuff that would minimize ground clearance loss with spring under. I plan to make something similar for my rig.
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