A seat track assembly for adjusting a seat assembly of an automotive vehicle. The seat track assembly comprises a lower track and slidably coupled to an upper track. A locking mechanism includes a fixed lock plate secured to the lower track and having a first plurality of apertures. A moving lock plate is secured to the upper track and includes spaced apart and parallel upper and lower locking plates sandwiched on opposing sides of the fixed lock plate. Each of the upper and lower locking plates include a second plurality of apertures for aligning with the apertures in the fixed lock plate. A housing is mounted to the moving lock plate above the apertures. A pair of shear plates are slidably disposed within the housing and have opposing offset engagement fingers. The shear plates are biased to a locked position for selectively engaging the first and second apertures to lock and secure the upper track to the lower track. The shear plates are moveable to an unlocked position disengaged from the first and second apertures enabling the sliding movement between the upper track and the lower track. Additionally, at least one of the shear plates is engageable with the first and second apertures regardless of a relative position between the upper track and the lower track to provide infinite engagement of the locking mechanism between the upper and lower tracks.