I know that on fullsizes that doing a shackle flip CAN affect the overall handeling when towing...does this lessen the overall payload capacity at all? (for example: hauling rock and other landscape material)

I think the lower capacities come from the extra height and the leverage placed on the components more than it does from the different suspension setup, after all many vehicles were built with compression shackles and they tow just fine.

I apologize...I just read the question above and it is misleading...

I know it affects towing (somewhat)

what I want to know is onboard payload capacity...not towing. when hauling a yard and a half of river rock am I going to have a failure when I hit a speedbump or dip?

is payload capacity less on a compression shackle than a tension....

Originally posted by mkbruin

what I want to know is onboard payload capacity...not towing. when hauling a yard and a half of river rock am I going to have a failure when I hit a speedbump or dip?

is payload capacity less on a compression shackle than a tension....

In my personal experience the answer to your question is yes and no. You probably won't have a failure but payload could be less because you're forcing springs which are intended to be arched to sit flat. This will reduce payload, if not immediately then over time as the springs fatigue (and they will). IF you run springs which are intended to run flat (military wrap would also be a good idea) then payload is not reduced IMO. You can even slap in an add-a-leaf which is nearly as long as the main leaf - as much support as you can provide around the spring eyes of the main leaf is GOOD. Hell, take a 2nd main leaf and cut it to provide a partial military wrap. So long as the leafs aren't overly thick you really won't notice much lost flex, because the shackle flip wants to put the springs in a negative arch during compression it's pretty good at forcing them to flex even if they're a little stiffer. Also, give it time, the springs will "break in" and relax (or fatigue depending upon how you look at it) and flex better over time. Again, in my personal experience, on my '90 fs Bronco FWIW

The only other factor for payload and/or failures is how your spring hangers are reinforced, gusseted and attached to the frame. As someone already said, leverage is increased. If you account for this leverage you're fine. In most applications you're fine anyway, but if you intend to haul heavy loads extra gusseting/bracing cannot hurt.

IOW, if everything is designed properly, payload is not reduced and no strength is lost.

thanks...that is exactly what I wanted to know/hear.