Great topic and I wish I could test the active camber adjustments also. Some people just want to know what works, but I always like to ask why also... Hopefully the pro's can leave some feedback on what works and why... I'm not a pro, but I'm a semi pro armchair engineer.
here's my thinking and experience on the adjustments in red below....
I will honestly say I could be wrong. But that's the result I came up with in testing.
There are a few things that we are able to change on the xray that the setup guides don't offer an details on. I've made my own assessments of what they do. But id love to hear it from the pros.
Active caster;
We are able to change the amount of active caster the buggy has by changing the angle of the top arm. What's the effect of running more or less.
1. If the upper pin is parallel with the lower inner pin there is no active caster and the caster will behave like a standard front suspension (XB9, Kyosho, Losi, etc)
2. If the upper pin is angled forward in relation to the lower pin, the castor angle will decrease as the suspension compresses and increase as the suspension unloads
3. If the upper pin is angled back in relation to the lower pin, the castor angle will increase as the suspension compresses and decrease as the suspension unloads.
I believe most setups including stock have the upper arm pin angled forward. I can only comment in theory, on what this does as far as feel on the track since I have not tested this. But in theory active castor can give the best of both worlds when done right. With the upper pin angled forward like example #2. I'm gonna guess on corner entry as the front end dives the caster will decrease giving more steering. On corner exit (on power) the front suspension unloads and the active castor will increase giving more steering.
Lower roll center;
Changing your roll center at the lower hinge pin plates as opposed to the upper link.
For the sake of comparison, let's assume you keep the same ride height and the front lower arms are level. Changing roll center on the upper pin would not change the ride height or lower arm angle. Changing the roll center at the lower hinge pin not only changes roll center but also changes the angle of the lower arm slightly.
1. Lowering that pin would lower roll center, and lower the mounting point of the arm on the inner pin. The arms would angle up more.
2. Raising that pin would raise roll center, and raise the mounting point of the arm on the inner pin. The arms would angle down more.
The difference in arm angle by changing the pin height is probably not gonna be felt by a regular driver like me. But I do know if the arms are running too far from level, the car handles funny (traction rolls, unstable etc) This adjustment will change the arm angle by a minute amount.
Hinge pin width;
We see it more on the xb8 with guys running 1 Bushing in narrowing the hinge pin width. What's it effect.
Hinge pin width changes track width. Narrow width makes the car steer more aggressively and less stable, more width does the opposite. I think Jason B mentioned that in an earlier post.
It also sometimes changes the dogbone plunge which affects how the suspension binds and stiffens/frees up when on and off power.
King pin angle as we've already said. There's a few more but these were all I could think of at the moment