School me on drop spindles...

What you're talking about is the difference between the spring rate of the bar and the wheel rate of the car. The amount of resistance provided by the bar, its spring constant, never changes. But, the rate that the wheel sees can, because of the change in the lever arm. Sure, that's right on.

And it's the "Wheel rate" that is really most important, not the spring's rate. The tire doesn't care what the spring rate is because it doesn't know what the linkage between is like. All it knows and all that it cares about is the wheel rate.

But, this isn't off road racing. The amount of travel for a bone stock car with factory bars at the factory height is in the neighborhood of 4". On a modified car like mine, its less than 2". So, does the wheel rate change over that 2" arc? Maybe a little, but not enough to be concerned about. More importantly, there's nothing you can do to change that unless you start changing UCA and LCA lengths. The suspension moves in an arc, the torsion bar reacts with a constant resistance, and the wheel rate varies slightly because of the change in the lever arm.

How much it changes really depends on where it's starting from. A little down from horizontal to a little up from horizontal, not much length change. 2" down from horizontal to horizontal is, percentage-wise, a large change given the total range of motion.

And that wasn't my point anyway. There's a misconception out there that lowering your car with the torsion bar adjusters changes your spring rate. This isn't true. The wheel rate isn't effected enough by that change to be significant. The resulting poor ride that most people encounter has nothing to do with that, but instead has to do with hitting/riding on the bump stops because they didn't increase the size of their torsion bars, or because of changes in camber, toe, and caster brought on by lowering the car.

Simply lowering the car with the adjuster changes the LCA's angle. That angle change effectively lengthens the lever length, which reduces the wheel rate. So yeah the spring rate hasn't changed, but the wheel rate has. The length change doesn't seem like its much, but it obviously is if the effect is a reduced "spring rate" as reported by many.

It is a definition of terms thing. The stiffer spring moves less in response to a given input. But I'm talking about the impulse curve of the suspension input. If you put a 400 lb impulse on a spring with a 100 lb/in rate, your suspension needs to move through 4" of travel. That takes time. If you put the same 400lb impulse on a spring with a 300 lb/in rate, the suspension only needs to move through about 1.3". That takes less time. A lot less. The spring moves less, but the suspension reacts faster to the input.

No, it does not react faster. The duration of the impulse event may or may not be shorter depending on damping, but this isn't reaction time. The reaction time is increased due to the force level needing to rise to the point where it over-comes the stiff wheel rate. A lower wheel rate begins to move at a lower force, an increase in reaction speed. By the time a high wheel rate is starting to move the lower wheel rate has already moved and the damping is starting to work to keep the tire in contact with the ground.

As far as hitting the bump stops, that's not ideal. Obviously, you want to soak up as many bumps as you can, because that keeps your wheels on the ground. But its a trade off. You also want to stay flat in the corners to keep load from transferring. So you have to balance that out. With extra sticky, wide modern tires, you need a lot of rate to keep the load from transferring. Which means you also like smoother tracks.

I contend that it is ideal, in moderation. You want the very serious bumps to use the limiters. Hitting them is very disrupting the chassis, so you shouldn't be hitting or even touching in normal use (even if "normal use" means racing), just at the extreme. You can go too stiff with roll wheel rate, your corner speeds will be indicative of this as they'll fall off. A supple and compliant suspension does a better job of keeping the tire in contact with the ground than does a ridiculously stiff suspension. Soft (relatively speaking) wheel rate to deal with surface irregularities coupled with a high roll rate for the corners.

Autoxcuda has a pretty interesting idea of using his bump stops. I'm guessing he never hits his...

Seriously bad idea there. The point of a bump-stop is to provide some deceleration to the suspension before maxing out in bump travel. The mount should be remade so that the bump net travel is the same, but metal to metal contact does not happen. Metal to metal contact in that location, especially in a highly leveraged situation like this one, is very hard on all of the parts involved - from the tire to the driver.

I'm not really sure what is going on in those graphs, but nothing that I see there is evidence to conclude that all dropped spindles have bump-steer. Given the separation of the steering arm from the spindle I can not see how a spindle of this design can have any influence on bump-steer unless they also change the KIA or possibly the BJ spacing. Then, maybe.