Now you guys have lost me completely. Either I don't get you, or the other way around. If I'm wrong (in fact, in either case) then please bear with me a little more and enlighten me. So:

I have a simple 8 sided box with diffuse, normal and height textures. That's my track.
In xNormal it looks just fine. But unfortunately I can't get that shader.
In A8 the direction in which the white "high" areas in the height map (wheels) are projected is almost the opposite to as it should be. The angle is my main problem (1) and that the wheels don't get lit as they are in xNormal (as deserved ).
Maybe you (JibbSmart) are talking about the different sides of the model, like top, side, under etc. Then I don't see how the edges between these faces would matter. I don't know of any other edges.