Do threads in forums that are NOT displayed in the node list get indexed in Google? I want to move some old threads into a hidden archive forum for potential reference purposes, but don't want to lose any link juice from Google.
Are they already indexed? If yes then as long as the URL is still reachable you should be fine. If no then Google needs some way of finding them in order to index them. That means having links to the hidden forum somewhere or using a sitemap generator and making sure that they are included.