Brake Line flaring

[Subzilla]

I'm replacing a brake line on the '84 S10 due to a rusty hole! I cut the line in half because of the extremely long length and am only replacing a section. So I need to put a fitting on the good "cut" end and flare it out. I go to buy the kit to do this and find a simple flaring kit AND a double flaring kit.

Which do I need? Single flare or double flare? When is one used over the other?

[DmaxMaverick]

You need the double flare kit. The tubing needs to be in pretty good health where you make the flare. Be sure to use a tubing cutter to make the cut (no hacksaw job), and ream the inside and outside well (remove any burs). If it splits when you flare it, the tubing is not suitable for flaring, which is likely to happen on old tubing. The end needs to be clean and perfectly square. You can keep cutting it until you get to a place it flares well, though. Don't "over-flare" it. Once the tubing folds in and is shaped like the anvil (the part the inner tubing it pressed against to shape it), stop. You don't want to squash and deform the metal. There should be a little space (width of a hair or less) between the inner and outer flare. The shaped inner flare should have at least 1/8" of smooth, clean sealing surface, on a 1/4" line, and a little more/less on larger/smaller lines. Tubing is measured/sized by the outside diameter, and hose by its inside diameter. Be sure to use steel couplers and nuts, not brass. SS is OK.

Single flare is for low pressure (less than 500 PSI). Your brake system can see pressures up to 3000 PSI (1500 PSI is typical, though).

[JohnC]

IMHO, not worth the trouble. Replace the whole line, or replace it in two sections.

[Subzilla]

Mav,
Thanks for the very detailed answer! That helps alot. You've been most helpful to me over the last couple of posts. Thanks! BTW, I used the old air cut off tool to get a fairly clean cut. Hard to imagine over 1500 psi in that little line!

John,
I first considered doing that. It's just that the rest of the line disappears into the frame and snakes around here and there. I first looked at it and the challenge looked like it would be more trouble. So I then chose the cut and flare route. I'm going to take another look at it tomorrow and see if I can get the rest of the line out. Then I'll decide to either flare or replace. I had to drop the gas tank skid plate just to get to remove bad section as it was nestled quite tightly between the frame and the gas tank. Gotta love that forethought from the automotive engineering industry.

Thanks for ya'lls help.

[JohnC]

If you decide to flare it, don't forget to put the fitting on the line first! :(

[Subzilla]

Yup, I thought about that a couple of times but knowing my short memory, I would have forgotten it once I started working on it. Thanks!

[Subzilla]

OK, so I started the flaring process on the line and dang if I didn't forget to put the fitting on first, John! I had to recut the line, put the fitting on, then start flaring again. It turned out fine after that. Got it all put back together and we're good to go. Thanks for the help.

[JohnC]

OK, so I started the flaring process on the line and dang if I didn't forget to put the fitting on first,


:o

Been there....