Split a stereo track into 2 mono tracks

I am trying to split a stereo track with left and right audio to two mono tracks with the left channel in one track and the right channel in the second track. I have been reading and all I seem to get is select the audio clip and then goto to Clip/Audio Oprions/breakout to mono. Unfortunately the menu item BREAKOUT TO MONO is greyed out and does not let me select it. I also read that you can force all clips to send the tracks to mono tracks on import. This will not work for me in this case I have already created the entire production and now I need to remove the channels that have ambient sound on them and just keep the tracks that represent the mics that I used on the set that day. I hope this makes since and someone can help me with this.
Thanks
Sean Kimbell

Hi Sean,

I've always just used "Fill Left" and "Fill Right" audio filters dropped onto the audio clip. I've had footage with ambient on left channel and wireless on right, I just add FILL RIGHT and then have wireless sound only on BOTH channels

Jeff Pulera
Safe Harbor Computers

Hi I was wondering if someone could explain to me how to split the stereo audio on import. I use a lavaliere mic connected to my GH2 audio in and so all the audio I record on the camera is just one channel on a stereo recording. I want to simplify my workflow and be able to make 2 mono tracks and delete the empty track and duplicate and pan the good track.
The "Fill left" "Fill Right" way works great, but just out of curiosity (final cut user style) How do I do it on import the other way?