301 redirect

I understand that 301 redirect passes most of the link juice, but is it permanent?
Lets say my 301 an expired domain to my money site(expired domain has clean BL profile) and the money site gets pen'd for SAPE links. Can I take the 301 off and redirect that expired domain towards another site and pass the juice to my new site? Or is it gone after the first 301?

It's not permanent it stays untill you move/remove the 301.
It depends if google catches the 301ing domain which probably shoulden't happen the first time.
But may happen after 5-10x as I read on the forums. I have no experience using it, but read alot of threads on this subject.

By the way don't index the 301ing domain as that's probably how google finds it.

It'll stay as long as domains are redirected.

Yes, you can change the 301 to other sites if your moneysite tanks due to some reasons.

Another thing, that most people miss is -- they do not maintain their 301s. Post ppl complain that 301 died in 3 - 6 months. Not maintaining/linkbuilding for them is the primary reason for that. They're just like normal domains and they need backlinks too - The linkjuice they pass, Has to come to them via their backlinks Simple as that.