PUR PONY, if you are doing any towing and want a stiffer ride, forget the shackles and go for the add-a-leafs. Add-a-leafs will do exactly what you described you want to do. I only got one inch lift out of mine though.
Warren, I've thought about this leaf flattening stuff too and couldn't figure it out and thought it was a bunch of hooey and hearsay, but guess what ended up happening to mine? They started flattening. I now have the shackles AND add-a-leafs. The effect wasn't immediate and may not be attributable to the shackles. Mine has a year of hard wheeling with the shackles now and maybe the wheeling itself wore the leafs out some.
If the shackles contributed, I can think of one theory that may make sense. There is no doubt that I got an increase in flex when I installed them. I immediately noticed that. The extra three inches of shackle length are not static. As you know the shackle pivots back and forth as the axle flexes. That arc-swinging motion allows for not only more vertical movement of the axle, but also horizontal movement within the leaf. What if (???) the fact that since the shackle on its backward swing stretches the leaf farther back (flatter), it helps wear it out that way? Think about it: at full compression with a tire stuffed all the way up into the fenderwell, the rear eyelet of the leaf spring will be stretched nearly three inches further back than would be possible with a stock shackle.
As far as I am concerned that's a real big maybe. I'm still more inclined to think that since I ride harder I stress the leafs sooner. Or possibly, a combination of both issues.
People who install shackles do so for a reason: to wheel better, so by demographic category they will wear any set of leafs out sooner than if they didn't install the shackles and kept the vehicle on the pavement. If anyones cares to experiment they could install a set of Warriors and then keep their SUV onroad, only using it like the other 99% of soccer moms, never flex the axle, don't tow anything, and see what the leafs look like in a year. Probably still bowed would be my guess. I wonder how many who have bought the shackles would fall under that category though. 0%?
Then again, who cares. This is a lot of discussion about a very simple mod's possible consequences and the concept could hold for any other mod. We modify our rigs, run them hard, and wear stuff out sooner. Case closed. Leafs, springs, shocks, clutches, body parts, brakes, grenaded diffies, etc etc etc; we wear 'em all out. I don't see a whole lot of difference.
Wheel hard as you are comfortable with and be willing to live with or replace the parts that your level of wheeling wears and breaks on your vehicle. This is all supposed to be fun. Don't do what you are not comfortable with or cannot afford.
[Edited by GJarrett on 12-01-2000 at 05:42 PM]