any tips on double flaring brake line, i am having trouble getting a proper seal on my fj40 brake lines. some seal, some don't.

Only really good brake line flaring tools seem to work well IMHO

Are you getting the proper double flare on your lines? Your flare should be centered on the tubing. If your flare is not even all the way around, it may leak. I have not had good luck flaring old lines that are not round. Any kind of kink in the tubing will not allow the flaring tool to work properly. Always flare on a straight section of tubing. I always try to use new tubing when flaring because it works better on the flaring tools that I have. Make sure your clamp is tight and the tubing is not slipping out of the bottom as you are trying to flare it.

Also,
Are you reaming the inside edge of the tube after cutting with a tubing cutter?
Are you setting the "stick out" for the first compression step at the correct height?
Is the clamping "anvil" tight?
Is the end to be flared on the champhered side of the anvil?
And, What jason said:flipoff2:

Sorry, the Auto teacher coming out again:D

Cory