I experienced the same problem with my '80, once lowered. These cars are based on the same chassis as the 5 series E12, as someone else has mentioned. I would recommend hooking up with Dinan Engineering for their adjustable camber rear subframe. It did the trick. They can adjust the camber for freeway use or just about anywhere else, including heavy camber for track use or light for highway use. And have them check the differential mount at the same time, as another also mentioned. I had this repaired at the same time. By the way, E24 models after 5/82 (I think!) are based on the E28 5 series chassis, so don't think about swapping parts out of any of these cars, including 635's. Good luck!