Method for downshifting an automatised gearbox

Method for changing down gears by one or two ratios in an automatic gearbox equipped with an input clutch controlled by a calculator comprises an initial declutching phase, a gear change phase (2) and a re-clutching phase. The latter phase comprises a first step (4) in which the clutch is partially connected and the engine speed is maintained at a target speed and a second step (5) during which the sliding of the clutch is gradually replaced by a controlled application of the transmission torques by the clutch.