Adjustment mechanism for motor vehicle seat

An adjustment assembly for a motor vehicle seat, comprising an adjustment mechanism and a flange that is part of a seat frame, the adjustment mechanism comprising:

• a housing, itself comprising a bottom and a cover,
• an output member having a base, an end opposite the base, and a pinion extending along a longitudinal direction between the base and the end, the pinion being mounted to pivot about an axis of rotation,
• a backplate comprising a base plate fixed to the flange and an upper part intended to partially receive the output member,
• a pumping mechanism housed in the housing and configured to drive the pinion in rotation,
• wherein the output member is in contact in the flange and in the upper part, the flange and the upper part allowing rotation of the output member about the axis of rotation, and wherein the bottom of the housing:
• comprises at least one assembly tab passing through the flange, the flange having a first face arranged on the housing side and a second face arranged on the output member side, the assembly tab bearing against the second face of the flange, and
• is spaced apart from the first face of the flange by a distance D along the longitudinal direction.