Today, after coming home for Thanksgiving, I heard a loud clunking noise and then persistent banging. I was very lucky to be less than 2 mi from home so I drove it home slow at 15 mph with my dad following me. Jacked the car up and saw that the torsional vibration absorber had come apart. The rubber between the inner and outer rings had broken and it was loose and flopping around my drive shaft.
http://www.realoem.com/bmw/diagrams/l/z/9.png part #2
I guess I'll just have to replace it.
