I have done brake line several times, and have the tool for making single and double flares. I believe most automotive applications call for double flares, where the cone of the flare is two wall thicknesses. The flare tool kit comes with several size dies for different size lines. Buy one and it's good just about forever for any vehicle that uses flare fittings. Then instead of buying short lengths and using a bunch of unions you get a 25' roll of the right size line and make the new section out of one piece. Don't forget to put the fittings on the line BEFORE you make the flares. I am guessing the rusted spot is where a clip held the line to the frame, maybe had a bit of sand holding water and acting as an abrasive on that spot? Check the rest of the length of that line for other potential problem areas.
The only time my flare tool kit didn't work for me was once on a car that had a wierd "donut" looking flare. I went to the dealer and was talking to the parts guy who had never seen one like it. As we were talking about it a mechanic came in and looked at it and said "You need a tool like the one I have out in my box". He made me up the flare in a couple of minutes and I threw him a ten-spot to have a few cold ones on me.
Last edited by thedaddycat; 01-19-2008 at 02:33 AM.