I may be misunderstanding, but I think you've missed the part where I tested this and the ride height is most definitely chnaged when you put on a fully adj susp. exactly how much lower it goes is not obvious so the setting you'd need to input would not always be the same for every car. It even lowers between the three stages of suspension upgrades.
Sports suspension lowers a little
Ride-Height Adj lowers a little more (default settings)
ANd fully adjustable lowers a even more (default settings)
Not sure I understand this. If you take two cars that have identical chassis but different suspensions, then rip out the suspensions of both cars and put custom ones in, then set both to have the exact same settings, both cars should perform exactly the same. If the suspension number still mean different things, then the suspension system in GT is a pretty bad hack.
I was talking about same exact car, not two supposedly different cars like these "toyotas".
If you take a 458 Italia, for instance (one of the cars I tested) and put the different suspensions on, the number "0" means a different thing for ride height on each suspension. That's all I meant.
However, if you and Turbo are meaning to discuss whether the FR-S, 86-GT, and BR-Z using a racing suspension with the same settinsg would negate the inherent differences in the cars from the factory, I do not yet know this.
However, I can say that the numbers PD uses to allow you adjust are relative. That is, relative to where the car began. Especially ride height. Lowering one car by -5/-5 might be slightly different than lowering another by the same amount.
What I've been able to glean from the knowledge of others, such as Dan_Zitions at the deathstar, is that it is best to first look at a car's inherent numbers in the stock suspension and then think about how you'd like to offset the natural tendencies of the car by adjusting some ratio betweein front/back etc.
if the FR-S's and its brothers have a spring rate of something like (off of memory) 7/4, and you really feel that you wantto even it out, nevermind the fact that when you add the adjustable suspension that it defaults at like 10/6 (if that's innacurate just try to see the illustration here) because it also defaults LOWER in height.
"ZERO" for ride height means something different for stock and for each stage of suspension you look at. using a racing suspension and making it say +10/+10 RH doesn't mean you're going higher than stock. In fact you're probably closer to stock in most cars.
"Zero" for spring rate really has no bearing on anything because you can't zero out a spring completely. So the better term is "default" which because they notate it with kg's we should be able to figure that the same amount of force acting on the car in one trim vs another would mean the same thing. However, it's not clear that the forces acting on each car in respect to how their suspension components are aligned with the car, SHOULD be the same.
If one car has it's rear struts angled at a -10 degree angle, and another model has -5, then the spring rates are not being utilized in quite the same manner, even if they are loaded with the same "tension". Make sense? And PD doesn't actually model that angle of the struts, as I concluded from my experiment with the game's Evo vs the real thing. They appear to get a similar result by simply changing the tension on teh rear struts so that it mimics the behavior of a strut that is angled.
I know, it's really hard to wrap our heads around. They need to explain things better, use mroe consistent terminology and figures to represent settings.