ldivinag, i'm going to nitpick a little here. i don't mean any disrespect, but i don't think you explained somethings right.
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Originally Posted by ldivinag
but guess what. in order to raise a TB suspension, you have to PUT MORE LOAD into it. cause as you know, when you "crank" the TB, that forces the upper and lower a-arms to point downwards. but now the TB is harder to twist to compress for normal suspension travel.
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when you crank the TB, you're not adding any load, you're just moving the eqilribrium point so that the front of the truck sits higher.
using hook's law for a perfect spring: F=k(x-x0), where F is the force on the spring, x is the position of the spring, and x0 is the equilribirum point. k is a property of the spring, we can't change that. F is the force on the spring (i.e. the weight of the front of the truck), we can't change that. so x-x0 is how far the spring is deflected from it's equilribirum position. no matter how much (within reason) we crank the TB, we do not change x-x0. what we change is x0 itself, or the starting place for the spring.
cranking the TB doesn't stiffen the ride, all it does is cause the A-arms to be pushed down, and the front of the truck to be pushed up. this gives a cheap lift and increases upward travel, but (unless you change your bump stops) it decreases the droop.
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Originally Posted by ldivinag
with a spacer placed on the top a-arm (btw, i heard that toyota and only toyota uses the upper a-arm design ON A TRUCK, to mount the TB. ford, chevy, nissan, etc, all mount their TB to the LOWER a-arm where they are more easily damaged by rocks and stuff), you get the best of both worlds: you can UNCRANK the TBs but still maintain the HEIGHT. and that is the magic that you can get for $120...
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what the space does is add space (hence the clever name
) between the lower and upper A-arm. it adds the space at the top, so that in effect it's pushing down on the lower A-arm, and giving some lift. as you said, toyota attaches the TB to the upper A-arb, since we're in effect messing with stuff below the A-arm, the TB and bump stops and everything remain uneffected. this way, we get a lift, but we don't sacrifice the droop to get it.
think of it this way. to lift the front end, we need to push the wheel down away from the truck. there are (at least) two ways to do this:
1a - we can push the whole upper A-arm down (cranking the TB). this is easy to do, but we lose droop because the upper A-arm can only go down so far
1b - we can put stiffer TBs on. This is like making a larger k in the F=k(x-x0) equation. so with the same F, the truck will sit higher. This is where you get the harsher ride that you were talking about. we also lose droop here.
2 - we can push the wheel down away from the upper A-arm (install BJ spacers). this is harder to do, but since we're not messing with the A-arm we don't lose any droop. The suspension parameters are basically unchanged.