Drivetrain jerk

[evldave]

I'd bet you my hummer it isn't axle wrap.

That's common on USED vehicles, with softer springs, and I honestly can't remember ever hearing of it on a axle-over-spring setup. I've got some experience lifting Jeeps and axle-wrap happens over time, mostly with cheapo budget lifts using lift blocks on stock springs after tens (or hundreds) of thousands of miles.

The reason is that lift blocks move the center line of torque (the axle) farther away from the springs, which puts much more torque at the point of contact on the springs (usually an area of 2x4" - the block). Over time, weakness builds at that point, and the springs start to S-coil. The taller the block, the sooner you will get axle wrap. The H3 setup (axle-over-spring) is significantly more stable related to this since the axle torque is inside the radius of the spring, not outside like SOA.

The best and cheapest way to get rid of axle wrap is an add-a-leaf. It will make your ride stiff as hell, but your axle won't wrap. Given the stiffness of the ride, I seriously doubt that anyone has enough (hard) miles on their rear springs to cause the # of issues that seem to be outlined on this thread. I'd even be willing to bet we could disconnect the rear swaybar and drive with no problems (I think there's another thread on that) - trust me, if you can disconnect the swaybar and drive around a corner, your springs are stiff enough to not have axle wrap as a problem.

Why do I (think I) know so much about this? Because my last off-road rig was a Cherokee and I spent the last year fuggin around trying to resolve a driveline/transfer case problem. It kept binding the driveline and trashing u-joints and one output shaft on the TCase. Well, my 5 year-old 120k mile 4" lift rear springs had pretty much failed and I was getting axle wrap. After spending all my time trying to diagnose the problem, I went out and bought some RE 3.5" springs, took out the rear swaybar and was a happy camper (and bought my H3 2 months later). The axle wrap as so bad, the pinion was pivoting up through centerline of the driveshaft at WOT in 1st gear, and then jamming when I went off throttle and it pivoted back down.