Hum good idea.

 

I'll just stay lurking in the back ground waiting for the results

I do agree that of you can learn to drive a ap1 s2000 at the limit you can get in any car and be able to drive it "well"

I have yet to get in a car that give me as much of a rush as my str s2000 when driving at the limit. The brakes on a porshe carrera gt did scare the crap put of me though. I honestly felt like I was going to get thrown thru the windshield.

 

what i am saying is that it appears that the SPC ball joint is in fact vertically taller then oem. i do understand the difference between camber and roll center
[/quote]


SO? anyone have oem and SPC for comparison?

 

I'll leave this here...

bushing install

https://www.s2ki.com/s2000/topic/484...nd-arm-refurb/

 

Reading some of this makes me want to try autocrossing an AP1...before I got my second AP2 I almost had a great deal on one too.

 

I agree that we really just need to understand the dynamic characteristics of the rear toe.

One additional data point that I believe is important along the curve is when the rear control arm is level. This would be when inner and outboard connection points are equal in height assuming the car chassis is level. I think this will be the point where the dynamic toe curve (slope or derivative) switches from toe out to toe in (changes sign) during compression. The opposite effect will occur during rebound.

Assuming this slope change occurs (hypothesis right now) you can then decide where on the overall toe curve you would like to operate by setting your ride height accordingly. I think if the control arm is slanted down from inner to outboard point there will be toe out on initial turn in during compression followed by toe in once past this point. If your ride height is low enough for the control arm to be slanted upward when at rest then only toe in would be experienced during compression. We'll let the data tell us what reality is. I also thing this point will be different for AP1 vs AP2, where on the curve the slope change is relative to the location in the compression/rebound stroke.

Also note that your springs, sway bars and shocks will control how much of the curve is used (traversed) for any given dynamic course situation. Higher spring/sway bar rates and shock damping will reduce how much of the curve is used. It could be that with a soft less controlled suspension the rear will be more "lively" because more of the curve is used.

So for anyone making the measurement please note on the curve where the rear control arm is level. Also note AP1 or AP2 along with year. We should be able to see if there is both toe out and toe in on the curve based on the shape.

Personally I don't care what the actual values of toe are through this toe curve. The only value of toe I care about is for alignment purposes. All the points on the curve are relative to the static alignment point and you cannot change (adjust) the curve. You can only change where on the curve you operate.

I may pull my right rear shock this weekend and try to capture the curve.

 

I have a feeling that this hypothesis is incorrect. I don't think that it's as simple this. The concept of "level" is a relative concept. Level to the ground doesn't have much bearing when there are multiple axis that the knuckle is controlled by as it moves through it's range. You have the axis that runs between the top and bottom ball joints of the knuckle (not level). You have the axis of the upper control arm mounting points (this one looks level). There is the axis of the lower control arm mounting points that's at a pretty serious angle relative to the upper CA. Then you have the axis of the toe arm mounting point relative to the upper and lower control arm axis which are not in alignment.

My kingdom for a toe curve! I mean, look at this thing. Axis everywhere.

 

I won't disagree with the complexity of the suspension and that "level" is relative or may not even be a correct word to use for this situation, but at some point on the curve I am betting that there is a transition from toe out to to in during the stroke in both compression and rebound. I look forward to some data to help us understand better.

 

I'm betting that in the range of motion we use, we will see only toe-in on compression and only toe-out under extension. The interesting part will be if that range of toe is more or less dramatic at different ride heights.

 

While I agree that actual values are not important (although they'd be nice, even if approximate), one thing that is important is figuring out when you're toe in, when you're at 0 toe, and when you're toed out. So however/whatever you're measuring, make sure there's a way to know this