New control arms are installed! The change in roll center is definitely noticable, and feels good. I'll try to explain in a bit.
First, by the numbers:
New control arm and ball joint setup places the outer pivot point about 1" lower than stock, and about 1/4" further out. This raises the roll center from about -0.5" to +3.0". Which should reduce body roll, move the wheel out 1/4" (and/or increase negative camber depending on how I adjust things).
Everything fit PERFECTLY with about 1/4" clearance from the bottom of the ball joint to the wheel. The only difference between the cheap aftermarket control arms and the stock ones is that some of the holes (not the critical ones) are not properly deburred on the cheap one, and believe it or not, there are more welds on the cheap one. Mitsu was trying to save weight and money on this car. There are places where they just welded one side of a joint, and the aftermarket part is welded on both sides. So, the stock part is lighter by that much, and had one less step in manufacturing. Interesting. That's how you make a car lighter, and how you can sell it for less money. Oh, and the factory ball joint doesn't have the snap ring holding it in. It's just a tight press-fit. (one less part, less machining on the ball joint, all replaced with one machine-crimping process)
I checked camber before I started. It was just under 3 degrees, call it 2.95. After the swap, it's right at 3.5 degrees. So, a gain of about a half degree. I'll probably dial that back, but maybe not. I've not been getting crazy camber wear at 3 degrees, even with the trip to Dunnellon, and driving it back and forth to St. Pete a couple times per week. As long as my toe is close to zero, I'm probably okay for the amount of autocross that I do.
I didn't check toe before, but I know it wasn't more than about 1/8" total toe. After, it was 3/4" total toe! (of course, that jives with the change in control arm length) Extending each tie rod end by 1 and 4/6 turns got the toe back to zero. Actually, it has just a breath of toe-out. Like 1/16" total toe. Good.
Didn't bother checking caster. It's not adjustable, and I didn't move the ball joint fore/aft, so it should not have changed the caster at all.
So, that's the math. That's what we've done. NO change in spring rates, ride height, or anything else. Just a significant change in roll center, and a minor change in camber.
Now, the FEEL:
Man, it's hard to explain. A lot of this will be lost to time. Once I get used to it, I'll forget what the difference was. So, I'm going to try to document it as best I can. First, yes, there is a definite difference that you can feel IMMEDIATELY. There is less body roll per the amount of steering input, but there's more to it than that. The body roll is still there. If you hang a turn, it rolls as much as it did before (more or less... probably less, but with larger steering inputs, it's hard to say "how much" less). But, smaller inputs, less roll. More precision.
That less roll and more precision feels really good in transitional maneuvers. But, the car also feels more "composed". This is a subjective thing. "Feel" is really hard to quantify. But, it feels like the front end is more connected to the road.
I can relate it to a caster change in a way. If you've ever played with Caster, you know how more caster angle gives you a sharper steering feel and more steering effort. And less Caster makes the car feel a little numb, but the steering effort goes way down. This sort of feels like less caster. The steering does feel a little more numb in a way... and yet, more precise at the same time.
Sidebar: One of the things I read somewhere (either in the Milliken book, or in one of the engineering forum discussions) is that if you could get your roll center and your CG at exactly the same height, you'd eliminate all body roll. Steering input would generate a force straight sideways. No body roll. As a driver, you'd HATE it because it gives you no feedback. A little bit of body roll is a good thing, it gives the driver's senses something to work with. So, by raising my roll center, reducing my roll couple -- I've reduced body roll, decreased one aspect of the driver's steering feedback, and translated more of the steering input into sideways force at the tire instead of into body roll. It's like a complicated balancing act. I definitely haven't gone too far with it. I have plenty of steering feedback, and body roll is still occurring. But, I can feel that more of my steering input is going into the tires vs. the body roll.
I can also relate it to a swaybar change in a way. You know how when you fit a fat front swaybar, your steering is suddenly WORLDS sharper and you have WAY less body roll? I'm pretty used to that one. This feels a little like that. Steering is lighter, but more precise. Swaybar would make it a little heavier, and more precise. But, there's a strange disconnect. The big front bar feel is accompanied by a change in ride quality. It's not "supposed" to. They say that a swaybar won't effect ride quality unless you hit a one-wheel bump. Well, guess what, you almost never hit a bump with both wheels at exactly the same time! So, yeah... a stiffer swaybar will, in my experience, always be accompanied by a somewhat harsher ride. So, that's the disconnect for me. If this was a swaybar change, I'd feel a lot of the same stuff... better steering response, less body roll... but, what I'm NOT getting is that harshness in the ride. My rear suspension still sucks, but the front... it's buttery smooth! The input and body roll feedback feels kinda sorta like a big front bar would, maybe with less steering effort increase... but absolutely no change in ride quality. Pretty cool.
Just puttering around on the street, so far I think that what the net take-away here will be is that because more energy is being fed to the tires in a sideways direction (rather than body roll trying to lift the inside tire), the front tires are staying more equally loaded. The reduced body roll and inside tire lift will hopefully solve my stability problem and make the car less scary to drive... or to watch. More evenly loaded front tires should increase cornering ability at the same time.
Any way you cut it, this is DEFINITELY an improvement. Very glad I did it so far!
I don't recall anyone ever getting pulled over in the FASTiva.
There are points involved 