A down hole drilling motor shaft security apparatus is disclosed. The apparatus has a general body housing threadedly attached to a lower radial bearing housing and an output shaft extending from the lower radial bearing housing. Within the general body housing is a thrust bearing assembly that secures a portion of the output shaft within the general body housing and the lower radial bearing housing. An intermediate sleeve having a capture groove of an elongated predetermined width is threadedly attached to the output shaft. An interference structure that is secured to the general housing extends radially into the capture groove in a manner that prevents axial loads from being transmitted to the intermediate sleeve from the interference structure while the bearing assembly is intact. The interference structure is configured to secure the intermediate sleeve and the output shaft to the general housing by engagement with the capture groove of the intermediate sleeve in the event of axial movement of the intermediate sleeve a preselected amount.