Is there a way to do full disk encryption after the install?
I have Ubuntu 11.10 installed with /home encrypted but really need the whole drive encrypted. I would really like to do that with out a re-install. Is there anyway to do that?
No. Part of full disk encryption, Truecrypt or otherwise, is writing random data to the hard drive.
Best you could do (without a re-install) would be to migrate your home to encryption or make a encrypted data partition. You could use Truecrypt or LUKS (I personally use LUKS).