Looking back from the driveshaft tunnel, spare tire well on the right.
Another common malady of the E9 chassis–and the later E12 sedans also–is stress fatigue at the rear differential mount area. Caused by inadequate care and replacement of the diff mount, as well as by upgraded engines feeding more torque through the driveline, when this area starts to go it is a true b***h to fix.
Better to forestall that first stress crack by reinforcing it first. Many ways to do this–welding in small triangles of metal to prevent flexing is another way–but the technique shown simply puts 3 spot welds where the factory chode to put 1, and in the most crucial and easily damaged areas. Need make sure to coat the spot weld areas with paint after all is done to prevent that other CS curse, rust.
