Cooper travelled down to the 1960 Argentine Grand Prix seemingly at the peak of their powers, and Trintignant won the Buenos Aires F1 event that preceded the main championship race. However this turned out to be the last major win for a T51, as the speed of the new Lotus 18 began to dominate. On the journey back, John Cooper made his mind up that to stay at the front he needed to build a new car, and at the next championship race at Monaco the lowline T53 made its debut. In the meantime Moss took the Walker T51 to second in the Glover Trophy and qualified on pole position for the International Trophy before retiring with wishbone failure. Rob Walker had already bought a Lotus 18 for Moss, but the Englishman was to miss a large part of the season through injuries sustained when his notoriously fragile Lotus lost a wheel at speed in Belgium. Cooper entered the T51 just three more times, with ex-Scarab driver Chuck Daigh and journeyman Ron Flockhart retiring each time.