It's worth noting that the car that Rick drove (glad you liked it Rick!) has the stock front bar and the 17.0mm Prius rear bar (modified) as well as the springs and dampers as noted earlier.
That said, my other car with no front bar also feels quite nice (very balanced, no scary oversteer) albeit with more body roll.
Cornering forces are primarily handled by the springs themselves, and a key ingredient of controlling the roll of any car is sorting out the springs first. Higher rate springs result in less body roll but often a harsher ride. This is why many factory suspension setups have soft springs (to be comfortable) and anti-roll bars (to keep body roll down to reasonable levels).
In the case of the Insight, they totally missed on the spring rate and ride height, springing the car so soft that it continuously bottoms out while simultaneously setting the ride height so low that the bump stops (which can be thought of as high rate progressive springs) are always engaged. At this point, with such a poor fundamental suspension setup, they added an anti-roll bar in for good measure as pretty much all Hondas have a front bar, some for good reasons, and some simply to guarantee very safe levels of understeer in order to prevent lawsuits.
So what we are doing here is first addressing the shortcomings on front spring rate and ride height, then considering the anti-roll bar once these fundamentals are sound.
To get the car to sound fundamentals (keeping in mind that it was never even close from the factory) we do the following:
-Raise the car up 1.0" to provide additional travel above the bump stops (controlled travel = traction)
-Trim the bump stops 0.5" to allow additional travel in the linearly sprung portion of the suspension (remembering that spring rate goes non-linear and traction is upset if we transition to the bump stops too harshly ... which a stock Insight does on every single corner and bump)
-Increase spring rate so that the car actually rides up on the springs and does not blow through its now increased travel (during braking, bump impact, and under cornering)
The final result is a car that has 1.5" of newfound controlled (linearly sprung and properly damped) travel on the front suspension where before we had springs sagging into bumpers and bumpers that are so stiff that they overwhelm the dampers (effectively oversprung and underdamped).
With these fundamentals addressed, the car ends up being more comfortable despite having stiffer springs on the front due to the fact that the car is now riding up on the springs (at 200 lb/in) instead of riding on the bump stops. The initial bump stop rate, once they are engaged, is very high and very non-linear (it ramps up to keep the car from bottoming out) which is why your teeth shake out in a stock Insight. You're riding on highly non-linear springs that can't be controlled by the dampers.
Since these replacement springs are nearly twice the rate of the stock springs, body roll is tremendously reduced, so much so that the original factory anti-roll bar is no longer a necessity. If the car had a strong front or rear traction bias remaining after getting the springs and dampers right, then it would be time to consider trimming the front/rear traction bias with anti-roll bars, but it turns out that this recipe is quite balanced.
It is definitely worth noting that my car with both a front and rear anti-roll bar is the crisper handling of the two but that both of them are very well balanced and neither has a tendency to oversteer (or spin out) unless you are actively coaxing the rear end around by feathering the brakes (or similar) on corner entry. If you were to just remove the front bar and not supplement the front end with stiffer springs, you would likely end up with a rather unsafe and very poor handling (worse than stock!) Insight.
A really excellent explanation of anti-roll bars can be viewed here: https://www.youtube.com/watch?v=WhWZ57baTOw
That said, my other car with no front bar also feels quite nice (very balanced, no scary oversteer) albeit with more body roll.
Cornering forces are primarily handled by the springs themselves, and a key ingredient of controlling the roll of any car is sorting out the springs first. Higher rate springs result in less body roll but often a harsher ride. This is why many factory suspension setups have soft springs (to be comfortable) and anti-roll bars (to keep body roll down to reasonable levels).
In the case of the Insight, they totally missed on the spring rate and ride height, springing the car so soft that it continuously bottoms out while simultaneously setting the ride height so low that the bump stops (which can be thought of as high rate progressive springs) are always engaged. At this point, with such a poor fundamental suspension setup, they added an anti-roll bar in for good measure as pretty much all Hondas have a front bar, some for good reasons, and some simply to guarantee very safe levels of understeer in order to prevent lawsuits.
So what we are doing here is first addressing the shortcomings on front spring rate and ride height, then considering the anti-roll bar once these fundamentals are sound.
To get the car to sound fundamentals (keeping in mind that it was never even close from the factory) we do the following:
-Raise the car up 1.0" to provide additional travel above the bump stops (controlled travel = traction)
-Trim the bump stops 0.5" to allow additional travel in the linearly sprung portion of the suspension (remembering that spring rate goes non-linear and traction is upset if we transition to the bump stops too harshly ... which a stock Insight does on every single corner and bump)
-Increase spring rate so that the car actually rides up on the springs and does not blow through its now increased travel (during braking, bump impact, and under cornering)
The final result is a car that has 1.5" of newfound controlled (linearly sprung and properly damped) travel on the front suspension where before we had springs sagging into bumpers and bumpers that are so stiff that they overwhelm the dampers (effectively oversprung and underdamped).
With these fundamentals addressed, the car ends up being more comfortable despite having stiffer springs on the front due to the fact that the car is now riding up on the springs (at 200 lb/in) instead of riding on the bump stops. The initial bump stop rate, once they are engaged, is very high and very non-linear (it ramps up to keep the car from bottoming out) which is why your teeth shake out in a stock Insight. You're riding on highly non-linear springs that can't be controlled by the dampers.
Since these replacement springs are nearly twice the rate of the stock springs, body roll is tremendously reduced, so much so that the original factory anti-roll bar is no longer a necessity. If the car had a strong front or rear traction bias remaining after getting the springs and dampers right, then it would be time to consider trimming the front/rear traction bias with anti-roll bars, but it turns out that this recipe is quite balanced.
It is definitely worth noting that my car with both a front and rear anti-roll bar is the crisper handling of the two but that both of them are very well balanced and neither has a tendency to oversteer (or spin out) unless you are actively coaxing the rear end around by feathering the brakes (or similar) on corner entry. If you were to just remove the front bar and not supplement the front end with stiffer springs, you would likely end up with a rather unsafe and very poor handling (worse than stock!) Insight.
A really excellent explanation of anti-roll bars can be viewed here: https://www.youtube.com/watch?v=WhWZ57baTOw
