The 31-year-old did not reach triple figures in any of his first 31 innings against the old rivals, but is currently unbeaten on 105 in the second innings of the fourth Test.
"It's been enjoyable this time to score some hundreds and maybe put to bed some of the stuff I have done in the past," PA Sport quote Bell as saying.
"I believed that I was good enough to score Test hundreds against Australia but it did take a while. My first two series were against arguably one of the best teams of all time. As a young player that was a real baptism. I learnt a lot from some great players.
"It's just nice to contribute. For us as a group we want to win the Ashes. We've done decently so far and tomorrow is a massive day for us."
England, looking to clinch the series victory, will begin day four 234-5 and aiming to build on a 202-run lead.