Modular door latch assembly

A modular door latch assembly comprising:

• a) a latch tube module for inserting into a cross bore hole of a door extending inwardly from a side edge of the door to a primary bore hole, the latch tube module comprising:
• a tubular housing having an outside end having an outside opening and being shaped to support the housing against the side edge of the door when the housing is mounted in the cross bore, an inside end opposed to the outside end, the inside end having an inside opening and being shaped to extend inwardly towards the primary bore hole when the body is mounted in the cross bore hole, and an inner wall extending between the inside opening and the outside opening defining a channel extending through the tubular housing;
• a latch bolt configured to extend outwardly through the outside opening and slidingly mounted within the channel of the tubular housing for extension and retraction along a longitudinal axis to latch the door to a door frame;
• and
• a connecting member coupled to the latch bolt and configured to extend inwardly through the inside opening towards the primary bore hole;
• and
• b) a cylindrical chassis module for mounting within the primary bore hole of the door, the cylindrical chassis module comprising:
• a cylindrical housing having a front face and a rear face opposed to the front face, each of the front face and the rear face defining a face opening for receiving a spindle-based driver of a door knob assembly, an annular wall extending between the front face and the rear face and defining an annular wall opening for receiving the connecting member of a latch tube assembly;
• and
• a locking mechanism disposed within the housing, the locking mechanism configured to couple to the spindle-based driver through the face opening and couple to the connecting member through the annular wall opening such that rotation of the spindle-based driver retracts the connecting member and the bolt to unlatch the door.