Does move one domain to a subdirectory hurt ranking?

[cache]

does redirect to a subdirectory hurt my page rank?

I have a vbulletin forum site located at
old_domain.com/
I would like to move it to a new site in a subdirectory in:
new_domain.com/forums/

I plan to do a 301 redirect as follows:

Options +FollowSymLinks
RewriteEngine on
RewriteRule (.*) http://newdomain.com/forums/$1 [R=301,L]

Do you think I would loose my page rank and links because of moving
to a subdirectory /forums/ ?

thanks.