Quote:
Originally posted by pnwbeers:
Shackles: Some claim that these cause the rear leaves to flatten over time. The only logical argument on this is that I've heard is that when the tire stuffs offroad the leaf will have to flex more (due to the longer shackle), which could possibly lead to sagging. That's the only argument that I've heard on the subject with any merit at all, and it may be true (though I'm not convinced). Other than the possible extra flexing, the spring doesn't have any idea that the body has moved 1.5 inches further away. I've had mine on over a year and still don't have any flattening. I figure if it does eventually flatten I'll get AALs to bring it back.
The reason the springs (can) flatten is from the springs point of view, the bumpstops have moved up 1.5 inches. Which means if you overload the rear of your truck, of offroad to the point that there is less then 1.5 inches from the bumpstops to the axle, you are pushing your springs flatter then Nissan designed for, (maybe reverse arched).
This is what will damage them, and cause them to flatten out faster, or break. I have never seen a broken spring on a 4x4, without a v8 (axle wrap), jumping (stupidity), or shackles(over load/flex).