Im getting the same noise... Going crazy and losing a lot of $$$ trying to figure out the reason. 4-5 rapid knocks when coming out of 1st / 2nd gear then its gone... Please Please Please let me know what you learn from this.
PS: I was also informed that it may be the integral link. #4
http://www.realoem.com/bmw/showparts.do?model=FA53&mospid=47745&btnr=33_1029& hg=33&fg=30