I also mention swaybar rating in my answer, something that P4S never mentions. I assume his calculations are without a swaybar, and THAT WILL NOT WORK either.
Based on my suspension geometry that features unusual upper-to-lower arm length ratio and more aggressive angle of the upper, body roll actually can be used to a distinct advantage. Given the quite high amount of spring rate (I recommended at least 450 lbs, but it's better to use around 550 lbs) and limited coil-over stroke, my suspension can perform quite well even without a sway bar. The lack of the latter could allow a softer ride on uneven surfaces, which is very important for a stiff suspension.
If we assume that the default camber angle of the front wheel is set to exact 0 degrees (though -0,5 degrees is recommended) while the car is moving forward (no turn at all), then the worst camber angle possible for the front wheel* is 0.874 degrees happening at 3.75 degrees of body roll (with -0.5 degrees default camber, that will translate to 0.374 degrees). The virtual point of body roll for this calculation is the middle point on the bottom side of the chassis. However, body roll during moving in forward direction is rarely the case. More important is what is happening with the car while in high-speed cornering. With the front left wheel turning at 15 degrees to the right side, the worst possible camber angle is -1.461 degrees at 3.24 degrees of body roll (or -1.961 degrees if the default camber was -0.5 degrees). This means that the wheel is still in a negative camber angle to prevent excessive tyre deflection and wear in contact with the road patch, as well as reducing the understeer. This is achieved thanks to the use of two toe links instead of a single upper A-arm. The toe links will dynamically alter both, the camber angle and caster angle, resulting in a suspension geometry with superior high-speed cornering performance, compared to a regular double A-arm layout.
*front wheel on the side of the car that's pushed towards the ground to create body roll.
This subject could fill another thread, but let me give this brief example more to show a concept than to be absolutely accurate. A 100lb spring and a 300lb bar gives a total rating of 400lb on that corner. A 300lb spring and a 100lb bar gives a 400lb rating on that corner. The debate over which is correct has been going on since the wheel was invented, but you must consider them together. When P4S says 400lbs on the front, that is as much as you would want to go for both combined, I do not care what the geometry looks like.
I do not agree with what you refer as to "absolutely accurate" in the above examples. There is no way that a 100 lbs spring and 300 lbs sway bar will give a total rating of 400 lbs on a corner, since the combined spring rate for both wheels would be 200 lbs, which can never be more than that number even if you have a 1,000,000 lbs sway bar. A 1,000,000 lbs sway bar will not help a 100 lbs spring to achieve 1,000,100 lbs on that corner. Also, 100 lbs spring and 300 lbs sway bar does not equal to 300 lbs spring and 100 lbs sway bar. This is not a simple mathematics where 2+2=4. They both can't be compared, as you did above. This is most prominent while hard braking from a fast speed in a straight direction. The 3 times softer springs will undoubtedly perform a lot worse then, not to mention that the sway bar will not contribute with hardening the suspension in this situation. What's more, a too stiff sway bar may hamper the stopping process on an uneven road.
Realistically, to get this rate you need about a 250 lb spring and a 150lb bar. A 7 inch spring coil binds at 4 inches, 4 1/4 to be exact. That leaves 2 3/4 inches of spring stroke, forget the shock. Place the 530lbs guess of P4S over it and it compresses 2 1/8 inches. That leaves 5/8 of an inch for suspension travel. Put a passenger in the car and you do not have even that. If he misses that guess by even 100lbs you do not have that. If the ride height is not absolutely perfect (which it is not going to be in the real world, only on paper) you do not have that. Change the air pressure in a tire and you do not have it. For that matter, what sized tire is this based on, will everyone use the exact same tire? When the spring settles, which it is going to do, you do not have it. All of these will leave it coil bound before the suspension ever has a chance to travel. It may look good on paper, but it is not reality. Go to a 225lb spring and now any slim remote hope is gone.
Why change it to the shorter shock in the first place? This is the same question I asked when my problems arose. The shorter shock and smaller spring is less unsprung weight but the bigger spring that is now needed negates this, and it is much harder to make the geometry work with the short one. I do not find an upside to this change.
Considering the limited stroke the front wheels require, a coil-over with too soft spring and too long stroke would simply cause unwanted damages to the chassis, if not accident. This is the main reason for me to choose a shorter coil-over with higher spring rate. Also, the shorter coil-over makes it possible to install it in a more robust area of the chassis.
Also on the downside, I understand you have two years of development using the Hardpoint for the longer shock, which is the first starting point of chassis design. You are going to lose every bit of your suspension analysis data. Again just my opinion but any chassis design that is changing Hardpoints after two years of development has more problems that the shock length.
In my opinion, devoting more time on optimizing a chassis and suspension design could further make it superior to the initial state. Changing means that something is not as before anymore. It could be good, or, it could be bad. In my case, it proved to be better.
