Device for distributing an engine torque between a first wheel set and a second wheel set of an automobile vehicle with at least two drive wheel sets, comprising: - a manual distribution mode selector switch, moveable between at least a first, stable, position and a second, unstable, position, the selector switch being mechanically returned from the second, unstable, position to the first, stable, position in the absence of any solicitation by the driver, the selector switch delivering a transient signal (S 2) for selection of an off-road mode when going from the first to the second position, - a torque distributor for distributing the engine torque between the first wheel set and the second wheel set, as a function of a torque distribution setpoint, - means for generating the torque distribution setpoint as a function of at least the movements of the selector switch and of the speed of the vehicle, comprising: - means for determining (31.1) a first setpoint value (C 1) for distribution of the torque, - means for determining (31.2) a second setpoint value (C 2) for distribution of the torque, and - selection means for selecting the first setpoint value (C 1) or the second setpoint value (C 2) as a torque distribution setpoint, the selection means going from the first setpoint value to the second setpoint value at least when the selector switch delivers the signal for selection of the off-road mode (S 2) while the speed of the vehicle is less than a predetermined threshold for engaging off-road mode (V pas), the selection means going from the second setpoint value to the first setpoint value at least when the speed of the vehicle exceeds a predetermined threshold for maximum speed in off-road mode (V max). - a manual distribution mode selector switch, moveable between at least a first, stable, position and a second, unstable, position, the selector switch being mechanically returned from the second, unstable, position to the first, stable, position in the absence of any solicitation by the driver, the selector switch delivering a transient signal (S 2) for selection of an off-road mode when going from the first to the second position, - a torque distributor for distributing the engine torque between the first wheel set and the second wheel set, as a function of a torque distribution setpoint, - means for generating the torque distribution setpoint as a function of at least the movements of the selector switch and of the speed of the vehicle, comprising: - means for determining (31.1) a first setpoint value (C 1) for distribution of the torque, - means for determining (31.2) a second setpoint value (C 2) for distribution of the torque, and - selection means for selecting the first setpoint value (C 1) or the second setpoint value (C 2) as a torque distribution setpoint, the selection means going from the first setpoint value to the second setpoint value at least when the selector switch delivers the signal for selection of the off-road mode (S 2) while the speed of the vehicle is less than a predetermined threshold for engaging off-road mode (V pas), the selection means going from the second setpoint value to the first setpoint value at least when the speed of the vehicle exceeds a predetermined threshold for maximum speed in off-road mode (V max).