Bubble flares and Copper/Nickel tubing

[The Carrot]

Morning Samba,

I am preparing to replace the two metal brake lines on the rear trailing arms of my Van. They are still functional, but the plastic coating has failed in places and they are showing signs of corrosion. While reading up on the copper nickel brake line and the flaring and bending techniques applied to it I began to wonder about the characteristics of the more malleable copper/nickel material itself.

Specifically when it comes to the formation of a bubble flare I see that there are two distinct bubble flare standards; DIN/ISO bubble flare which is what came on the van, and then there is the SAE bubble flare. (Stage 1 of an SAE inverted flare) The tooling that I am practicing with can produce the SAE bubble which has an angled transition from flare to tube vs. the square transition of the DIN/ISO bubble. I can see that the brake tube nuts do not appear to be interchangeable, so I am wondering if it is appropriate to simply replace the tube nuts for those with an appropriate chamfer to match the SAE bubble flare.

Given that the copper/nickel brake tube is more malleable am I correct in my understanding that the final tightening of the tube nut into the associated brake component ( for example the wheel cylinder) will have a final forming effect on the bubble flare to the sealing surface of the component, a final “crush” akin to a copper sealing washer on a banjo bolt. Bentley is mum on tightening torques of hydraulic fittings, so I was wondering about that too. Since the original tubing is steel on steel, what is recommended for the softer metal on steel?
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1990 Orly Blue Carat

[skills@eurocarsplus]

you need the proper bubble flair and tube nuts to match the metric stuff on the car. it will leak otherwise.

you will need to buy the double bubble flair kit if all you have is a standard kit at your disposal. they have special dies in the kit to make the bubble
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[pbrown]

You can probably buy pre-made tubing with the proper metric fittings and bubble flair at your FLAPS (I hate this acronym BTW). Then bend to fit the area. It won’t be a perfect fit as there are only so many different lengths available.

Another option is to get a single long piece and cut it to length from each end. This will give you one good flair and you’ll have to add the other. Don’t forget to insert the nut before adding the flair. I’ve been there many times.

Get the best flair tool you can afford. The low cost units are tricky to get a square and symmetrical flair. Read the product reviews.

Good luck with your project.
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Patrick Brown

1986 Westy Syncro EJ25
Flickr --> https://flic.kr/s/aHsmQNUXEF

[nemobuscaptain]

[crazyvwvanman]

Yes, the South America trip happened, back in 2000.

That trip was actually the trigger for Syncro De Mayo which then spawned Syncrofest.

Mark

[Vanagon Nut]

[DanHoug]

i really like the Cu/Ni line and highly recommend using it due to the corrosion resistance. plus it is so dang easy to get the bends where you want.

you CANNOT simple replace the tube nuts with SAE fittings because the seat area of what the tube nut screws into is also ISO/DIN shaped. buy the correct flaring tool and practise. i have 2 different ones for ISO/DIN and each has good and bad reviews on the net. probably the one i use the most is the OTC one but i'll still goof up flares with this.

the only time to use an SAE flare on our vehicles is when you are joining two lines with a coupler. then it doesn't matter what flare is used as long as the tube nuts and the coupler match.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Jeffrey Lee]

I've had difficulty making trustworthy flares using sub-$100 tools on the new copper-nickel tubing, so I often use pre-made poly-coated steel lines with the nuts already installed. As mentioned, they're available in something like 10" increments, so measure up each piece of hard line you need, and buy pieces slightly longer than that. Bend to shape, using the original line (or a section of stiff wire) as a pattern.

If the new piece is, say, 4" too long, just add a 4"-circumference loop somewhere that won't interfere with anything. I like to make loops oriented horizontally to aid bleeding, and I coil them in a direction that will encourage air bubbles to migrate toward the bleeder.

A tubing-bender tool like this one is quite versatile for bending a variety of curves in brake lines, and usually includes a few different sizes of dies for various diameters of tubing.

Good luck!
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Camp Westfalia
Camping Tips • Newsletter • Cool Campervan Apparel
www.CampWestfalia.com

[MarkWard]

I have an old wheel cylinder that I will seat a newly flared tube into a few times prior to installing. That seems to help.
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☮️

[Vanagon Nut]

[The Carrot]

I am using this tool for my initial training on creating a bubble flare on the copper/nickel brake tubing that I bought for the job.

https://cal-vantools.com/products/bubble-iso-in-line-tube-flaring-kit/

Look closely at the clamping blocks and you will see that there is a chamfer in the clamping blocks and that is resulting in a flare that looks like this:

SAE Bubble Flare

Contrast with this.....

Din/ISO Bubble Flare:

I note that the sealing face of the two flares is the same so my question remains; what about replacing the M10x1.00 tube nut for the DIN/ISO flare with a M10x1.00 SAE Bubble flare tube nut.

The reply by mark ward leads me to want to try this in an old brake component on the bench as he suggests. I am not interested in replacing the rust prone steel lines with more steel lines of indeterminate length, so I want to learn to form and shape the copper/nickel tube.
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1990 Orly Blue Carat

[Thor-bob]

Great line can be had at Federal Hill:

http://www.fedhillusa.com

and you may buy it in metric sizes for fuel and hydraulics also.

Cunifer is the bomb for me-last-long-time lines, BUT.... you are dealing with brakes here, so practice making flares until you are happy (perfect), then the rest is gravy.

Do Nots:

1. Don't have long and heavy lengths unsupported... I worry about fatique from vibration over the long haul....... Pure Copper will work harden and fail quickly, so treat this alloy nicely and it will do the job. This applies to making pretty loops that make the install easy.

Do's:

A. Try to mimic the original line - remember that the trapped air wants to float up when bleeding.

B. Buy the best flare tool you can afford - True Dat. Use oil and practice.... you will learn, Luke.......

C. Follow best practices and remove any burrs that form. After forming the end, CLEAN out the line.

D. Have a blast hand-forming this magical line and wrenching it home. Gob's o' fun, and you did it all-by-yourself!


This line has such great properties that I bought big rolls to do all the 25+ YO autos in the family. Don't care that it may cost points in a Concours, it's a safety thing.

Not Van Related Content:
American cars pre-fuel injection used a mechanical pump at the engine that sucked gas from the rear mounted tank. The galvanized metal supply line was clamped to the inside of the rocker panel, and would often rust under the clamps. Tiny pinholes formed, and whilst not really dripping gas, air could be pulled in while trying to start the car after a few days of sitting. The symptom mimics vapor lock.... Most people think to add an electric booster pump back at the tank to "solve" the problem, without going through every inch of the line first. Think about it - the car worked OK when it was new.... so what changed since then? I was gob-smacked when I learned that that rust happened this way..... hence the fascination with Cunifer lines.

Just sayin'.

Also, Speed bleeders are neat.

Thor-bob

[tbd]

Just a note, I replaced all the lines on my 89 with CuNi and found that it does not work well to use one of the copper tube rolling cutters. It would form a little ridge around the opening just like in your pictures. I did a few test installs and found that the ridge would make the opening "crush" smaller than the ID of the tube. I switched to cutting the tubing with a Dremel and cut-off wheel, it gives a nice flat cut. The resulting flares did not crush any further so the hole in the end was the same diameter as the ID of the tube. Also cleaned up the cut with an inside/outside burr remover.

[vanagonjon]

You can use a nice quality tubing cutter, but it will also distort the end of the tube. Use a good hand file and file the end of the tube flat and true. Deburr the inside of the tube with a deburring tool or a nice sharp pen type knife. The end of the tube should look perfect with a nice flat face and no burrs at all. Practice getting it right. It is like painting, preparation is 80% of a good flare.

I bought a Blue Point (SnapOn) ISO (bubble) flare set on Ebay for a very reasonable cost. It makes a good ISO flare for me.

You will need to practice to see how far to extend the tube out of the block for the first of the two presses. Varying the extension will change the final product quite a bit.

Joh

[Abscate]

If you remove the wheel cylinder bolt and can move the cylinder and flare, threading is a breeze!
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.ssS!

[tjet]

[The Carrot]

This weekend I picked up an Eastwood vise mounted flaring tool. Orders of magnitude better than the previous types that I have used.

I found that using the cunifer tubing only requires a mild amount of force to form the flare, then as poster MarkWard suggested, I did a final forming of the bubble in a spare brake component off of the Van to finish the flare. I prefer using the SAE bubble flare with a chamfered tube nut and the copper tubing allows me to do this.

Nice to have the tooling provided by the Eastwoood tool to experiment with the different flares. I did learn that there appears to be unmarked “cunifer”tubing sold at the flaps, and then there is the SAE marked tubing which has noticeably thicker tubing walls. Went with the SAE tubing for consistency.
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1990 Orly Blue Carat

[vanagonjon]

I didn't think the DIN/ISO and SAE bubble flare were different things. Either you have a bubble flare, or a double flare. Some folks call the DIN/ISO bubble flare an SAE. You can look it up.

John

[DanHoug]

i like this site for the flare naming conventions... their information is correct and you can scroll thru 7 images of flares.

http://www.fedhillusa.com/?page=flare
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[The Carrot]

The SAE bubble flare is an older seldom used type of bubble flare. The important difference between the SAE and the DIN/ISO bubble flares is in the type of tube nut that is required. Here is a link to an image of the “old style” bubble flare with what they are calling a Girling Tube nut.(page 1, lower right) I have also heard of the Flare itself referred to as “Girling”. http://www.fedhillusa.com/webnuts/common%20flares6.pdf

Here is an image of the two flares in question:
(Disregard the Double Flare)

Now that I am making consistent quality flares, I am trying to establish a benchmark torque tightening value.
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1990 Orly Blue Carat