I had BTC in my Bitcoin Core wallet before the BCC fork, but I didn't claim the BCC before transferring my BTC to another wallet after the fork. Is it possible to claim the pre-fork BCC even though my Bitcoin Core wallet balance is currently 0? If yes, how do I go about claiming the BCC from my Bitcoin Core wallet?
What you did after the fork on the bitcoin blockchain has no effect on the BCC chain at all. All that matters is what you had at the time of the fork. You can follow the regular BCC claiming instructions.