A clutch mechanism configured to be driven in rotation about an axis and comprising two assemblies (1, 2), each assembly (1, 2) comprising at least: - an outer disk carrier (106, 206) externally delimiting a cavity (C1, C2), - a clutch (100, 200) comprising a stack of coupling disks (101, 201) and friction disks (102, 202), the stack being housed in the cavity (C1, C2) and configured to be driven in rotation about the axis, - a reaction member (103, 203) of the outer disk carrier (106, 206) configured to enable compression of the coupling disks (101, 201) against the friction disks (102, 202) in a clutch engaged position of the clutch (100, 200), the clutch mechanism comprising at least one device for assembling the two assemblies (1, 2) to one another, each the outer disk-carriers (106, 206) of the assemblies (1, 2) comprises at least one first extension (1003, 2003) extending radially outwards beyond a peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206), at least the first extension (1003, 2003) of one outer disk carrier (106, 206) facing at least the first extension (1003, 2003) of the other outer disk carrier (106, 206), the assembly device comprising at least the corresponding first extension (1003, 2003) of each outer disk carrier (106, 206), characterized in that the reaction member (103, 203) of at least one assembly (1, 2) comprises: - a first part extending radially mainly outside the cavity (C1, C2), that is to say beyond the peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206), and - a second part situated inside the cavity (C1, C2), that is to say inside the peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206). - an outer disk carrier (106, 206) externally delimiting a cavity (C1, C2), - a clutch (100, 200) comprising a stack of coupling disks (101, 201) and friction disks (102, 202), the stack being housed in the cavity (C1, C2) and configured to be driven in rotation about the axis, - a reaction member (103, 203) of the outer disk carrier (106, 206) configured to enable compression of the coupling disks (101, 201) against the friction disks (102, 202) in a clutch engaged position of the clutch (100, 200), each the outer disk-carriers (106, 206) of the assemblies (1, 2) comprises at least one first extension (1003, 2003) extending radially outwards beyond a peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206), at least the first extension (1003, 2003) of one outer disk carrier (106, 206) facing at least the first extension (1003, 2003) of the other outer disk carrier (106, 206), the assembly device comprising at least the corresponding first extension (1003, 2003) of each outer disk carrier (106, 206), characterized in that the reaction member (103, 203) of at least one assembly (1, 2) comprises: - a first part extending radially mainly outside the cavity (C1, C2), that is to say beyond the peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206), and - a second part situated inside the cavity (C1, C2), that is to say inside the peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206). - a first part extending radially mainly outside the cavity (C1, C2), that is to say beyond the peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206), and - a second part situated inside the cavity (C1, C2), that is to say inside the peripheral edge (1001, 2001) of the corresponding outer disk carrier (106, 206).