Some parts of object are always completely black (with glossy shader).

So I’m beginner in modeling and now I’m trying to model a tractor, but I have problem I can’t solve.

When looking the rendered image, some of the parts are always completely black, even when I have background light giving light everywhere. If I mix Diffuse shader with glossy shader the diffuse shader seems to have effect to dark parts, but glossy shader doesn’t effect any way.

I tried to attach the project file and picture of the problem. I am new on this forum, so I hope I got them with the post

Attachments


täryjyrä_1.blend (497 KB)

You have smoothing issues which become very obvious when you in effect just use 100% of the very glossy shader.

Your model has a mirror modifier but you haven’t removed the faces that will be inside the mirrored mesh along the centre line (turn off the mirror modifier to see)
You also need to control the shading with something like auto smooth or edge split modifier https://docs.blender.org/manual/en/dev/modeling/meshes/editing/smoothing.html