ok, i'm Mr thicky.
Just realised that the ARB is a torsion bar (d'oh), i guess meaning that one side can move independently via the bar twisting if enough sudden load is placed of that side.
I think part of my confusion whilst playing around with the movements on my 1:8 buggy is that
a) It's a 2.8mm dia ARB bar so it's relatively thick (??)
b) I don't yet have the wheels mounted or the engine etc back in which presumably will increase the ability/willingness for the bar to twist whilst driving more so than me working the suspension by hand on a car stand.
c) I've also got the drop links set a little way from the ends of the bar thus decreasing it's ability to twist.
...there, see, i've answered my own question
