Has anyone found or calculated suspension dimensions such as center of gravity, roll center and motion ratios? Also scrub radius and mechanical trail?
It would be really nice if there were engineering dimensions available, that would locate important points and planes like the angle of the strut tower top.
I have a factory service manual that has projected underbody dimensions and the side view has a reference line that can't be the ground (only 3.5"), does anyone know what this references, maybe the lower ball joint?
Thanks for any help and ideas.

 

Have any fellow autocrossers and racers ever gone into this detail of our suspension? I know all this data can be physically measured but I am hoping for a gracious gift of information or perhaps a source of factory engineering drawings if they exist to the general public.

 

Oh and I drive a 87 sport with no sunroof in STR class. And have 255/40R17 Rs-3's on 17x8's with 27mm offset, if anyone was curious.
My main goal is to have ideal suspension geometry; increase castor, king pin angle slightly, lower minimally, reduce bump steer and decrease mechanical trail. I believe I can accomplish this and be legal in street touring with an idea I have.
locally I beat most miatas except two, and our club is almost half miatas. And I am running stock everything except coilovers an tires/rims, and will soon add headers and a fuel tuner I bought for this season

 

if you do a little searching you can find most of this info, but its probably best to measure your car, as things like roll centers depend on ride height.

 

I did a lot of searching but found nothing, I even tried contacting mazdaspeed through email ( no response ). can you provide any sources?

 

Oh and of course I found all the basic stuff like king pin angle, castor angle, camber angle and ride height.
The Rx-7 book by Jack k. Yamaguchi provides a lot of info on the KM hub, and my driving experience has told me to leave it alone; smooth turn initiation makes the rear steer very predictable and desirable.

 

Good luck fixing all that and keeping the struts!
There's no such thing as "ideal". It's all a series of compromises.