Stainless Steel AN Brake Lines

[Mike.Bray]

Hello everyone. I've seen a few comments and had some questions & PMs sent to me about my stainless steel AN brake lines. While my car is away at the paint shop and I'm stuck with an empty garage I thought I would share some tips on making SS AN brake lines that I've learned over the years. Just throw it all out there in one place for you.

When I first started building street rods back in the early 80's I attempted to go down the 45 degree double flare automotive route. I bought a flaring tool:


Never got the hang of it though. No matter how hard I tried I just could not make a good double flare. One day I ran across a small shop here in Dallas that sold Earl's fittings and brought up my struggles with flaring while I was there. The owner either took a liking to me or felt pity as he spent quite a bit of time showing me all about working with hard lines. He showed me the 37 degree AN stuff, how to flare and bend it, and from then on I was hooked. Looking back I realize it also meant he would sell me a lot more Earl's stuff lol

37 degree AN lines and fittings come from the aerospace industry and are literally as good as it gets. Honestly, for street cars they are way overkill. But they look soooo nice!

Tube
Obviously you want stainless steel tubing but not just any SS tube will work. You need either type 304 or better, type 316L material. It must be seamless and must be fully annealed. 3/16" OD x 0.028" wall thickness is the size, -3 in AN speak. You can get it from Earl's or Brakequip. Dash numbers are the size in 16ths so a dash 3 is 3/16".

I have used tubing cutters before like this one but you have to deburr the ID with a countersink. Most of the time I use a fine-tooth hacksaw or maybe a Dremel with a cutoff wheel.

Benders
For benders I prefer level style. I have a set of old Ridgid benders from 3/16" up to 1/2"


Unfortunately I don't think Rigid make these anymore but Fragola make 3/16 & 1/4" ones that I found here.

The lever benders give you nice tight bends without kinking and are very precise. My Ridgid benders came with great instructions showing how to achieve bends in exactly the right place.


Sorry for the quality, or lack of, with the instructions but they are over 40 years old.

This is my 3/16" Ridgid lever bender.


I wanted to point out a modification I made to it. AN fittings have a sleeve that backs up the single flare. For tight bends near the tube end the sleeve needs to be installed, the tube flared, and then the tube bent. With bends 90 degrees or less the nut will go around the bend so it can be installed later.

I milled a notch in my bender to give the sleeve clearance and allow the bend to be as close to the tube end as possible. Very handy!


Flaring
As mentioned these are 37 degree single flares so you need the appropriate flaring tool. I have this one although today I think it's about $400. Ouch! It is a very good quality aerospace grade tool with hardened rollers that burnish the flare. But honestly not really necessary for street cars. Eastwood has a nice flaring tool that I understand can be ordered with a 37 degree tip for AN fittings.

One thing that is really important when forming 37 degree AN flares is to use the depth stop for the tube. All 37 degree flaring tools will have a stop as the tube must be at the correct depth. Otherwise the flare will be too deep or too shallow and it won't seal.


Fittings
I've always used Earl's fittings and never had an issue. Other brands might be a little risky, I've heard horror stories. On my street rods I used aluminum fittings and never had an issue. Obviously steel fittings have a higher PSI rating and with the FFR Cobra and its big Wilwood brakes and huge tires I felt more comfortable with steel fittings on the pressure side. In addition to the nuts & sleeves you need for the tube Earl's has all kinds of adapters & fittings. Anytime I go through something I use a bulkhead fitting just like the aerospace industry. Probably a little overkill but I fell better about it.


Tube Clamps
These all kinds of fancy machined aluminum clamps, again Earl's is a good source. Lodestone has some nice ones but kind of pricey. I used quite a few of these and really like them.

Flexlines
Not much to say here other than you want -3 PTFE lined hose rated for hydraulics and at least 3000 PSI. I tend to use either Earl's or Wilwood premade hoses for brake and clutch flexlines.

If you've read this far you are a much better person than I am. But I hope this is helpful and not confusing.

[Mike.Bray]

A few more images as my original thread limited me.

A couple of bulkhead fittings I used.


Lines out of the master cylinders.


Flexlines on my 32 roadster. I took a piece of round stock, drilled thru it, and tapped from each end with a 1/8" NPT. Then welded it into the frame to pass the brake line through.


Fuel lines on an EFI injected blower setup for a BBC.

[Nigel Allen]

Thanks for taking the time to provide a great write up, along with pictures. I love learning new stuff on this forum, even if I don't have a need for it right at this time. There is an awesome assortment of people with an abundance of skills, gained from their career or their hobby. It is certainly worth appreciating.

Cheers,

Nige