Weird shading problems i have never seen before

Hey guys. I have a problem with some parts in my scene. There are some shading problems at the edges of some faces. There are NO double faces, the normals are checked. Did I miss something? Please help, I have a lot of experience but never encountered these problems…

Looks like overlapping faces which you said you don’t have. The only other thing I can think of is if you have your viewport/camera clipping distance set too small. This can cause strange issues but they generally don’t look quite like what you have.
Are you sure you don’t have overlapping faces? You can have overlapping faces without overlapping vertices/doubles.