Technical director Ross Brawn explained that the Maranello-based team, off the pace at Melbourne and Sepang, had almost completed the design of the F2005's new transmission when the '05 regulations became clear.
"We realised our transmission and engine package was not very good," the Briton told Motorsport News.
"So we needed the extra time."
Brawn said enforced changes to the diffuser, in particular, made necessary a fundamental shift in engine and gearbox.
He added: "We decided we didn't have the right package, so we had to start again. Whether it was right we can judge at the end of the year." -GMM