Self-adjusting spacer device, comprising: a bushing having a cavity with a longitudinal axis, a pin having a shank inserted into said cavity and a head projecting outside of said cavity, the cavity of the bushing and the pin being provided with respective threaded portions that do not extend over the entire circumference of the pin and the cavity, and the pin being rotatable relative to the bushing between: an adjustment position in which the threaded portion of the pin is disengaged from the threaded portion of the bushing and the pin is capable of moving axially with respect to the bushing, and a locking position in which the threaded portion of the pin engages the threaded portion of the bushing and in which the pin is locked axially with respect to the bushing.