|Don't let this happen to your springs. Springs can deflect to take this shape under load, when the pinion has rotated up in reaction to the torque applied to the tires|
Axle wrap is a problem that plagues leaf sprung vehicles with soft springs, particularly those that are set up SOA (Spring Over Axle). Axle wrap is something different than wheel hop. Wheel hop is when an axle on your 4x4 rapidly hops up and down. Axle wrap is unwanted suspension movement that allows the pinion angle to change. Wheel hop is annoying and could cause drivetrain breakage, but usually it's not the actual hopping that breaks parts, it's the axle wrap that results from the hop that causes drivelines to bind and breaks yokes, drive shafts, and sometimes even pinions.
It's hard to reduce wheel hop without going to stiffer springs or shocks which can reduce articulation and change the ride and handling characteristics. Axle wrap can be nearly completley eliminated with no effect on articulation or handling.
Some of the basic concepts
There are few things to know and definitions to understand before we begin the discussion:
Read more of A look at axle wrap prevention devices on the 4x4Wire Archives