From Dave Mandl, who follows us via Twitter: “Palm Grease,” from Herbie Hancock‘s Thrust (1974).
After the tonality wanders around a bit in the first few minutes of the tune, a stronger key change happens at 3:00, where Dave explains that “the piece moves from a bridge in F minor back to the tonic, A minor. I’ve always loved the way the bassist (Paul Jackson) slinks back to A minor. That main bass riff is a classic — the drum beat, even moreso. The piece is in 4/4, but drummer Mike Clark kind of splits it up as 9/8 + 7/8. It’s got to be one of the greatest funk grooves of all time — and that key change is one of my favorites.”