The present invention is generally directed to a drug delivery device for selecting and dispensing a number of user variable doses of a medicament. The device comprises a housing (10) having a tubular portion (12) with an inner thread, a piston rod (30) having a threaded portion (31) and a distal end, and a bearing (140) having a distal face and a proximal face. The bearing (140) comprises a retaining stem (142) protruding from the proximal face. The piston rod (30) comprises a distal portion having an outer diameter which is smaller than the inner diameter of the inner thread of the tubular portion (12) and comprising at its distal end at least one retaining clip (33, 33′) engaging the retaining stem (142). The axial length of the tubular portion (12) is smaller than or equal to the axial distance between the proximal face of the bearing disc (141) and the distal end of the threaded portion (31) of the piston rod (30). During manufacturing of the device, the retaining clip (33, 33′) engages the retaining stem (142) prior to the inner thread of the tubular portion (12) engages with the threaded portion (31) of the piston rod (30).
