Break line help

[cope99]

I'm having issues with my stainless steel brake lines. The lines are double flared (flared with a handheld Vevor hydraulic flaring tool) and seem to be in good shape, however the union at the master cylinder is leaking when I vacuum to bleed the brake lines. Any help or suggestions would be greatly appropriated.214947214948

[JohnK]

Get a small jeweler's loupe from Amazon or wherever, and inspect your flares very closely under magnification. SS is easy to get micro-cracks in when flaring. When I was doing my SS lines, there were a couple that looked fine to the naked eye but had tiny cracks when inspected under magnification. Luckily they were on smaller pieces so easy to re-do.

Edited to add: After some practice, I realized that the micro-cracks were a result of applying too much pressure on the second flaring step. With a lever-actuated tool like the Eastood tool I was using, you can get a "feel" for the correct amount of pressure with some practice. With a hydraulic tool it's possible that you're applying way too much pressure and not even realizing it.

[Derald Rice]

Most brake lines (and AN fittings) are a 37 degree flare, and a lot of flaring tools have 45 degree dies and cones.

On SS lines, annealing can help with preventing the micro cracking..

[JohnK]

The standard SAE brake line flare is a 45 degree double flare. AN flares are 37 degrees, and use a different die set.

[rich grsc]

Get rid of the pigtail's in the line. Make them the correct length, better results & looks.

[cope99]

Get a small jeweler's loupe from Amazon or wherever, and inspect your flares very closely under magnification. SS is easy to get micro-cracks in when flaring. When I was doing my SS lines, there were a couple that looked fine to the naked eye but had tiny cracks when inspected under magnification. Luckily they were on smaller pieces so easy to re-do.

Edited to add: After some practice, I realized that the micro-cracks were a result of applying too much pressure on the second flaring step. With a lever-actuated tool like the Eastood tool I was using, you can get a "feel" for the correct amount of pressure with some practice. With a hydraulic tool it's possible that you're applying way too much pressure and not even realizing it.

I bet you are correct, I go pretty hard on it for the 2nd flare. Thank you!

[cope99]

Good to know, yes my flare tool is 45 degrees... that would cause the problem. Looking into annealing, thank you.

[cope99]

Thanks, would you also use annealing vs the harder SS?

[cope99]

I was under the impression pigtails were recommended for brake lines vibration dampening, flex and thermal expansion. It would be easier to leave out.

[Mike.Bray]

45 degree SAE double flares on stainless steel tubing is a very tall order even with fully annealed tube. My recommendation would be to use NiCopp for SAE double flares or 37 degree single flares for AN fittings.

[Mike.Bray]

I was under the impression pigtails were recommended for brake lines vibration dampening, flex and thermal expansion. It would be easier to leave out.

They are actually for OEM cars where the master cylinder is mounted to the firewall on the body and the body is mounted to the frame with rubber donuts. The pigtails take up the relative movement between the body and frame. This does not apply to an FFR Cobra.

But steam gauges.....

[cope99]

They are actually for OEM cars where the master cylinder is mounted to the firewall on the body and the body is mounted to the frame with rubber donuts. The pigtails take up the relative movement between the body and frame. This does not apply to an FFR Cobra.

But steam gauges.....


Mike, I came back to my post to ask a few other questions in regards to dealing with AN fitting and stainless steel lines, I noticed your thread link on stainless steel AN brake line below... super, super helpful, I wish I had noticed this before. Thanks for putting this together, it helps a newbie like me, big time.

[Tooth]

I was having similar issues with ss lines. Finished the lines, then took them all out and made nicop lines. Just felt more confident that all my connections would be better with the nicop. Not a material issue, just a user issue in my case. I have all the nice flare kits that go in the vice, just wasn't getting consistent looking flares with the ss.

[OB6]

I was having similar issues with ss lines. Finished the lines, then took them all out and made nicop lines. Just felt more confident that all my connections would be better with the nicop. Not a material issue, just a user issue in my case. I have all the nice flare kits that go in the vice, just wasn't getting consistent looking flares with the ss.

With the SS, were you using a 37 single flare (AN) or 45 double flare?