I made a model of a winch in Blender for the Hopper. It looks good in the program but when I export it to BeamNG, it looks like this: video: Did I miss a step or something while exporting the model in Blender? Note that I have not got to creating a jbeam structure for the winch.
Have you tried flipping the direction of the normals? EDIT - You're actually flipping normals. My bad!
Alternatively, highlight everything ('a' on keyboard) , click the "mesh" button on the bottom toolbar, then "Normals", then "Recalculate Outside". This should attempt to fix it automatically for you in a more intelligent way than flipping all normals. In my experience it very rarely fails. It attempts to figure out what should be outwards facing and make it so. This way if some are the right way around and some are the wrong way around it should figure it out rather than inverting the problem.