actually on all the mn12's that i have seen, including my own, the rear lower control arms have a factory toe adjustment ecentric on the bottom, and a factory camber adjustment eccentric bolt on the top. if tha camber went negative by 2.5 degrees, then factory camber adjustment should be more than enough to bring the rear camber within specs. oh and if the bolt just spins but doesnt move the camber at all, you can still loosen the bolt up and "push or pull" the wheel to desired specs, unless the bolt is broken.