New forum sub-domain SEO strategy?

[len backus]

I operate a forum with a 7 year old domain name and I am about to start 2 more forum sites as off-shoots of this one and with their own, new domain names. Is there any way to set up the new ones as "sub-domains"of the 7 year old one in a way that they would get the same search engine juice that older domains get because of their age?

[briansol]

subdomains are treated as external sites more or less.

i think you'll find that domain age isn't very important. content is king.