I will create categories on new forum install manually.
But how to transfer Members, threads and posts from old SMF? ((But thread forum IDs change I guess?)
I searched the forum. It's been asked few times. I haven't seen any solution in those threads.
possible?
What is your end goal? Seems like what you are trying to do isn't going to work. Are you trying to move your content from one domain to another?
No. On same domain.
I want to reinstall the SMF and move data to new install.
You probably just need a new set of files
http://wiki.simplemachines.org/smf/How_to_upload_a_fresh_set_of_files