Tangents calculation gone wrong

Hi! I've downloaded model from 3d warehouse and reworked it completely(some holes in it, bad geometry, unwrapped it), but when i import it in unity and set shader to bumped specular i get the model lit up like nuclear explotion, or(if i change import settings) bumped correctly, but completely broken by separate parts like it has randomly flipped normals. I've spent few days but haven't find any answers what could it be and how to fix it. Any ideas?