Abstract: The invention concerns an apparatus comprising a housing (12) with a radial wall (14) coupled with another input shaft, a turbine wheel (104) coupled with a hub (54) and an output shaft; and a lockup clutch comprising a piston (40); an annular friction disc (152) with global radial orientation, coupled in rotation with the turbine wheel (104)/hub (54) assembly and bearing on a first surface a first counter-track (210) co-operating with a first friction track (200) integral with the piston to define a first annular friction zone (Z1), and which bears on its second surface opposite to the first surface, a second counter-track (230) co-operating with a second friction track (220) integral with the radial wall (14) to define a second annular friction zone (Z2). The invention is characterised in that the first and second friction zones (Z1, Z2) are radially offset relative to each other.