Well, if you've been following the Custom Control Arms
discussion, you'll know that I have solidified a plan. Here it is:
Ball Joint Extenders/Spacers are out. Can't work practically for me for a variety of reasons. Going with an off-the-shelf extended ball joint instead. That limits me to 1" of extended ball joint length (was previously targeting 1.5-1.75"), but with much more confidence that stuff won't break (the ball joints I'm using are regularly used on 4000 lb cars).
To fit said ball joint, I'm going to have to modify the lower control arm to receive it. Not a big deal, just a little cutting and welding. I was trying to avoid it, but it's not difficult or scary. Spare lower control arms are already on the way.
To acheive my goal of getting the roll center height above 3" with just 1" of ball joint height change, I'll also be extending the lower control arm by 1/2". In addition to being a factor in determing the roll center geometry, that will also have the effect of making the front track width wider, and without requiring a wheel spacer to do it. Win-win.
The last thing I'll be doing to help with the roll "moment" is actually raising the front of the car by half an inch. Yes, this raises the CG, but it raises the roll center MORE than the CG, thereby reducing that "roll moment", which is effectively the length of the lever through which the weight of the car is applied to body roll.
There is also some benefit to having the front slightly higher than the rear on a FWD car, which is a different discussion.
A lot of this is discussed in greater detail in the other thread. But, in a nutshell:
Stock CG (estimated) - 20"
Stock Roll Center (calculated) - 5.75"
That gives a Roll Moment of - 14.25"
Goal should be to be no MORE Roll Moment than that, and ideally less.
Less Roll Moment designed in the suspension geometry = less body roll and more stability... even without adding roll stiffness.
Simply lowering the car by 2.5", netted:
Lowered CG - 17.5"
Lowered Roll Center = -0.5" (that's BELOW ground level)
Lowered Roll Moment - 18"
The new plan, lowered 2" and with modified control arms and tall ball joints:
Modded CG - 18"
Modded Roll Center = 3"
Modded Roll Moment = 15"
Still not ideal, but should be a lot better.