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My '76 F-150 4X2 LWB truck has an auxiliary leaf spring that looks like this:
... but my '76 F-100 4X2 LWB truck does not. I'm assuming that this difference is part of what justified the F-150's higher GVWR which, in turn, justified emissions and other exemptions for the F-150 that the F-100 didn't get.
From the looks of it, this aux leaf does nothing until the load gets pretty high so I'm wondering about whether it is really necessary for my purposes. This F-150 has an older Class V Draw-Tite hitch with a 2" receiver. My 18' dual axle trailer uses a 2.5" ball and would probably never pull more than 5K pounds.
So what things should one consider before removing it?
At what trailer and tongue weights does it kick in?
Is it better to leave it in if other, fully active leaves are removed for a softer ride?
How does this aux leaf interact with common lowering techniques?
How does it interact with traction bars, Cal Tracks and the like?
1. No idea, depends on where the load is (weight in the bed, hitch weight, etc.)
2. I'd say that's a good plan, if you're shooting for stock height, and is more/less the idea behind them. If you built up a stock pack to carry the weight, they'd be REALLY stiff empty. One thing to watch, though, is that the clearance from the overload to the hangers stays the same as you drop leafs from the main pack - otherwise, you get close enough that they bang every time you hit a bump.
3. Lowering would be the same issues as above, they get too close to engagement so any suspension travel will cause a bang and a bounce. The other issue would be an angle change, say you changed rear shackles and changed the level orientation, one end would contact too soon.
4. would think it'd be okay with traction bars......
1. No idea, depends on where the load is (weight in the bed, hitch weight, etc.)
Thanks for the reply Jake. I think that hitch/tongue weight would be where I apply the greatest stress. A two axle trailer with a 5,000 lb. load wouldn't apply that much weight to the truck, no?
2. I'd say that's a good plan, if you're shooting for stock height, and is more/less the idea behind them. If you built up a stock pack to carry the weight, they'd be REALLY stiff empty. One thing to watch, though, is that the clearance from the overload to the hangers stays the same as you drop leafs from the main pack - otherwise, you get close enough that they bang every time you hit a bump.
Using the trailer scenario above, I wonder if the aux leaf will ever get used.
3. Lowering would be the same issues as above, they get too close to engagement so any suspension travel will cause a bang and a bounce. The other issue would be an angle change, say you changed rear shackles and changed the level orientation, one end would contact too soon.
Makes sense and seems to argue for removing the aux leaf should lowering be attempted. I'm thinking of DJM shackles or, more radically, an axle flip.
4. would think it'd be okay with traction bars......
Sway bars should be fine with 'em, have a 250 with both from the factory. As long as everything clears physically, which it should, they have different functions that don't really interfere.
As far as the trailer weight, you'll be 400-600# or so at the tongue? Since you've got a lever-effect, it's compounded at the axle by a factor of roughly 1.5, if I remember right, so you could guess maybe 1000#
Trying to guess spring rates when "customizing" packs is pretty tough - unless it's an engineered and tested spring pack it's pretty much all guesswork at how much squat you'll get at load, etc. Years ago, we did a lot of that stuff at my "college" job, working at a trailer sales place. When dealing with lowered vehicles, the fallback was aux. airbags or Timbrens, that way you had a safety factor to keep from bottoming out without having to really engineer a whole new spring pack.
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