DIY stainless brake lines ( hardlines)

[mc1984ss]

On my next project it is going to require all custom bent brake lines. I would love to do stainless but am getting a little gun shy because a lot of people seem to struggle with them and getting them to seal. I am not sure if this is due to faulty tubing, a bad flare tool or???? I have access to a hydraulic flare tool so I feel.very confident in that. I've made my own stainless lines in larger diameters so I know what I'm up against. I've just never don't my.own stainless hardlines that see that kind of pressure. I'm open to tips and suggestions. I'd also like to know who sells a coil of quality stainless brake line. Thanks!!

[camcojb]

My thoughts...

With stainless I use a cut off wheel to cut the line, and then dress the end from there. There is a consensus that tubing cutters work harden the end of stainless tubing and can crack. With that said, I had used a quality tubing cutter in the past for years without issues, your mileage may vary.

I use AN fittings when I build stainless brake lines which are 37 degree vs 45 degree. With 37 degree I do a single flare. Use a quality tool (mine is a Ridgid (https://www.speedwaymotors.com/37-Degree-Flaring-Tool-for-Stainless-Steel-Line,9067.html?sku=91089524&utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE)). If you think you're going to do more of this in the future for fuel lines or future projects and the budget allows I just picked up a flare lapping tool from Koul Tools (https://www.speedwaymotors.com/Koul-Tools-P-51B-Sure-Seat-Lapping-Tool-Kit-37-45-Degree-Flare,246739.html), leaves a perfect sealing surface on the stainless flare.

In the past I still had stubborn fittings that leaked (before I used the lapping tool), so now I just use conical an washers (https://www.summitracing.com/parts/ear-169212erl?seid=srese1&gclid=CjwKCAjwx7GYBhB7EiwA0d8oe937o6rZ2XRSGCjDgsoL 5l8erzwY5pa4xhyjADU1uGPrKqYa5FAppRoCMmQQAvD_BwE) on all the AN connections. They come in aluminum and brass, and the softness of the washers allows the connection to seal even if there is a small imperfection in the stainless flare. I do this automatically to prevent any leak issues when I go to fill and bleed the system, cheap insurance.

[mc1984ss]

Excellent advice. I actually own the Ridgid tool and have used it on larger diameter tubing with great success. The conical sealing washers are something that I try to keep in stock and I get them from pegasus racing. Thanks for telling me about the burnishing tool. I actually searched for one in the past but couldn't find one at the time. Who's brake line do you prefer and where are you able to buy it?

[dontlifttoshift]

+ one on the lapping tool.

I get the stainless seamless tubing from McMaster in straight, six foot lengths. Order your fuel lines at the same time and get extra of both....paying shipping for one tube sucks.

[camcojb]

Excellent advice. I actually own the Ridgid tool and have used it on larger diameter tubing with great success. The conical sealing washers are something that I try to keep in stock and I get them from pegasus racing. Thanks for telling me about the burnishing tool. I actually searched for one in the past but couldn't find one at the time. Who's brake line do you prefer and where are you able to buy it?

I've actually been buying my stainless tubing from Mc Master Carr. (https://www.mcmaster.com/tubing/smooth-bore-seamless-stainless-steel-tubing/) Most local AN fitting places also carry it. For 1/4" (#4) brake line I'd probably get .035" wall thickness. For 1/2" fuel line get the thicker tubing (065") so it doesn't wrinkle when bending.

[joeko23]

I used nicopp lines for my build. It was my first time doing brake and fuel lines from scratch. I bought the nicopp line from Amazon for like $20 for 20 or 25’. It was so cheap that I made the brake line then had enough left over to make a template for fuel line. It was super easy to bend and do double flares best of all so far no leaks!

[Pro Touring Store]

+1 on the McMaster 6' lengths.

Another thing to mention, is I prefer to use stainless tube nuts and sleeves. I've seen the effects of over tightening aluminum tube nuts, and I'd like to never have that risk on a brake line.

[IMPALAMAN1]

I use .028 wall seamless stainless. for 3/16, 1/4, 3/8 I have had good luck with it, For 1/2" it will flat spot on tight bends. If you can find a place local to you to get stainless tubing some will deliver it for a small fee. For the most part you are going to be under 10' for your longest run.... I don't like putting in unions if I can avoid it. if you need to, relocate an adjustable proportioning valve to under the car. once you set it.... it is pretty much left alone. I have used aluminum and stainless fittings on the stainless line. if you are an all out race car pushing the limits of brake pressure you may want to do it all in stainless.

some will argue that aluminum fittings will stretch over time. considering a stock vehicle may use a brass Tee or brass ends on a steel line. I think for street cars the aluminum is a viable option. I will say that an aluminum fitting can round off just as fast as a brass one. the stainless... not so much.

for cutting I use a rigid hand cutter. and deburr the ends. I also take the time to file them flat. yes file. I have found if you miss anything on the deburring and try to flare the tube, you end up with a sort of Galling mark.

for the actual flaring I use what is called a Roloflare. I think it was an aircraft tool originally. mine does 3/16 to 3/4. in a 37 degree flare. it is a hand tool and will give you a workout.

this is like the one I use but a different brand.
https://www.aircraftspruce.com/catalog/topages/flaringtools2.php

keep it oiled nice on the threads and the tip.


I have used the hydraulic tool and find that it is cumbersome and gets heavy after being all over the car. and if you have a line in a tight spot, it is almost impossible.

another tip..... I absolutely hate uncoiling tubing. buy straight sticks if you can.

use your scrap pieces to have generic bends. place them where you need and make your bends on the long pieces. tape them to the care and measure between them.

If you mess up..... fix it. you now have a template for what you need. They are brakes or fuel nitrous or fire suppression. A simple $30 line and 2 tube nuts and 2 sleeve could be the cause of a failure.

last, take your time to map it out on the car, painters tape... pinstripe tape. a marker. if you have the factory lines they may show you a route to follow.

[DRJDVM's '69]

I did all my brake and fuel lines in SS. non seamed, as a complete newb..... and I was shocked NONE of them leaked.

I used Rigid flare tool and what I did was clamp the line in the tool with my cut line on the back flat surface of the tool, then use a fine hacksaw to cut it flush with the flat side of the tool.... that gives you a nice 90 degree cut or damn close.....file it dead flat with the tool surface, then debur the inner edge..... then take the tube out, flip it around and flare

Everything I read was to avoid putting heat into the SS before you flare it.... hence the fine hack saw by hand at low "RPM" and a file.... no power tools.

Mine worked great.... I was kinda shocked since it was my first time at doing flares.

I did have a few goofs with not getting the bend quite right.... of forgetting to put the tube sleeve or nut on before flare :)..... but none of the flares leaked on me