My shank wasn't long enough to penetrate the door and the insulation inside the door. I cut out the glued in insulation, drilled a hole in a 1/4" backing board. I put that board flush against the metal inside the door and tightened down my shank retaining nut on that. Then I used new styrofoam to fill in the gaps behing the board bringing it back to the level of the original insulation.
Make Beer, Not War.