Neither of your designs has enough negative roll axis (IMHO)... That second one looks downright dangerous for street driving (2.5* of roll oversteer!
)
-G
So, what kind of a target roll axis angle should I be targeting? I understand negative is good, but how many degrees negative?
I disagree, my truck has several degrees of roll oversteer and I drive it on the street all the time one handed, it handles perfectly fine because my steering is in good condition and I have plenty of caster.
I'm the odd one here, but I think everyone over reacts and says to shoot for negative because it has evolved in to what it wasn't supposed to. Yes, understeer is better than oversteer, negative is better than positive. If you have to err on one side, err on the side of understeer if possible, it can work well.
However, since when do we want our trucks to steer us when we hit bumps? Ideally it would go perfectly straight when we hit uneven bumps. I know when you start a turn the body lean has an effect. So if you start a turn and then it leans over and turns more, that is less desirable than if you start a turn and it leans over and turns less.
I still say shoot for zero, and if you get some negative thats fine. But to be honest, I think caster is more important. If your caster is wrong, your roll steer can magnify the issues which caster causes.
1.9 should be fine you just need some. But too much is almost as bad.
It defines whether your front axle steers into the turn or fights the turn. If your number is positive it will fight the turn if its negative it will steer into it.
I agree, too much is just as bad. However, I think you are backwards on the negative/positive thing.
I'd been aiming for closer to 60% and I think I will tweak it a bit yet to get it there. I like having the front end dive a bit under braking, but at the same time I don't want the front end to lift any when I am trying to hill climb. I'd rather have the front stick down and loose some of the dive vs having to use a suck down winch to keep the front end from unloading on a hill climb.
Anti-dive only works when you are on the brakes. When climbing a hill in 4WD it won't have the same effect, and if it does, it will be opposite, it wil want to dive under power, which counteracts the raising nose and has little effect.
The reason is because the direction the axle housing is torqued determines how it reacts against the links. When applying the brakes it torques the axle housing and tries to raise the vehicle, under acceleration it torques the axle housing the opposite direction and tries to lower the vehicle.
This is backwards from the rear suspension which is called anti-squat. Antisquat tries to raise the vehicle under acceleration, and lower it under braking.
However, when applied backwards (antidive under acceleration and antisquat under braking), they have little effect because of weight transfer, leverage, and traction.
