Thanks!
Tonight, I finally managed to make Primal Prime walk on all four like a gorilla. Wasn't easy, had to redesign the hip transformation to make the leg higher and farther back to make them shorter overall. So instead of flipping just the front wheels to the back, now the whole wheel-fender-upper leg joint swing around to the back. Also slightly redesigned the neck plate to allow the front part to fold down to hide the gap it creates when I want the head to look up. The only downside is that the damn thing is really fragile now because of the outrageous number of joints to achieve the transformation. Superglue to the rescue once I know I'm 100% happy with the model!