Brake line flares

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Mark Luichinger
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Brake line flares

#1 Post by Mark Luichinger »

Replacing my MC with a dual MC. ED at Klasse pointed me to the correct lengths of tubing and referred to using a VW supplier. When checking the tubing the flares seem different than my originals. Both to me are bubble flares but the after market bubbles seem not to be as robust. Wondering about the quality’s of the flair. Hate to go to all the work of bending the lines and find out I bought junk. What say you?
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David Jones
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Re: Brake line flares

#2 Post by David Jones »

Try your local parts house. They all sell various lengths in all configurations and in inconel.
Usually very good quality I have found.
If I had known I would live this long I would have pushed the envelope a little harder.
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Patrick Ertel
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Re: Brake line flares

#3 Post by Patrick Ertel »

The one that looks like a bubble is an ISO Bubble Brake Flare used in older European cars
The flatter one is a DIN Mushroom flare use on Asian cars and modern US and European cars.
It's hard to find the old ISO flare any more, but as far as I know you CAN use the DIN flare in a ISO fitting as long as you use the DIN nut with an unthreaded "lead" on the end. I have, and I haven't had any trouble with leaks.
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Martin Benade
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Re: Brake line flares

#4 Post by Martin Benade »

Isn’t the nut with an unthreaded lead a problem going into an old shallow fitting? I think the regular “”nut” would be better.
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Mark Luichinger
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Re: Brake line flares

#5 Post by Mark Luichinger »

Both lines I have have unthreaded leads. I have done some more research and it appears the iso and din are considered the same. But there is no specific statements that Din is backward compatible nor are they incompatible. Given with Patrick’s real world results I would say they are compatible. David I did go to local source and they do not have the older(iso)flare. They are calling th mushroom (din) style a bubble fitting. Thanks everybody. It’s a little clearer but not definitive
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Re: Brake line flares

#6 Post by Patrick Ertel »

Martin Benade wrote: Thu Dec 01, 2022 2:09 pm Isn’t the nut with an unthreaded lead a problem going into an old shallow fitting? I think the regular “”nut” would be better.
I'm just reporting what I read when I researched this last year when I replaced the lines in my Speedster. The ISO fitting in the OP's picture has the unthreaded lead. Whatever. The end of the nut does need to be flat with a small chamfer, not flared. Notice the back side of the flare is 90 degrees to the brake lines the OP.
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Mark Luichinger
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Re: Brake line flares

#7 Post by Mark Luichinger »

Sorry forgot to add this photo of the new line with fitting
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Re: Brake line flares

#8 Post by Jon Bunin »

The factory manuals have a section on flanging (flaring) brake lines, and Porsche provided a tool to do so.
The text and illustrations are the same in the pre-A, A and B/C manuals.

The manuals don't show a flare facing the fastener, and the 5mm hole in the tubing vise will not create one.
Even so, I do seem to recall some 356 brake lines with some degree of fastener-side flare.
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Re: Brake line flares

#9 Post by Patrick Ertel »

I don't understand the use of that tool. The upper images show the brake line being held in some sort of flat faced die and the flare being formed with a round, punch-like die.This appears to form a DIN style flare. But the bottom two photos show a die with a beveled holes and tools with tapered ends. These tools would produce a common single flare as on a domestic copper gas line.
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Martin Benade
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Re: Brake line flares

#10 Post by Martin Benade »

I think just the smallest hole in that tool is for brake lines, that one is square shouldered as it should be.
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Re: Brake line flares

#11 Post by Jon Bunin »

Patrick Ertel wrote: Fri Dec 02, 2022 10:41 am I don't understand the use of that tool. The upper images show the brake line being held in some sort of flat faced die and the flare being formed with a round, punch-like die. This appears to form a DIN style flare.
But the bottom two photos show a die with a beveled holes and tools with tapered ends. These tools would produce a common single flare as on a domestic copper gas line.
Patrick, the tools are consistent with the illustrations.

As Martin said, the 5mm hole in the tubing vise is square-shouldered and will not create a flare on the fastener side.
In the 3rd image, the punch nearest to the tubing vise is also consistent with the illustrations.

The illustrations include flare dimensions and angles, for Mark to compare with the brake line(s) he purchased.
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Re: Brake line flares

#12 Post by Hugo Karasawa »

Are these the correct bubble flare that we should use in our Porsches ?

This one with the green tubing are from PolyArmour.
Bubble Flare 1.jpg
bubble flare 2.jpg
This one with the silver tubing from Wagner.
bubble flare 3.jpg
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Re: Brake line flares

#13 Post by Al Zim »

Without digging through the inventory I believe that we have sold over 1500 dual master cylinder kits. This includes the master cylinder VW style and all the fittings to properly install it including the front metal brake lines. You are welcome to call Doug at 817-267-4451 and he can help you figure out what you need. Zim
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Martin Benade
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Re: Brake line flares

#14 Post by Martin Benade »

Hugo, those look fine.
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Patrick Ertel
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Re: Brake line flares

#15 Post by Patrick Ertel »

To Hugo: I can confirm that those flares work with the old ISO fittings in our cars.

Al: I installed one of your kits in my '56 coupe. I don't notice any difference in braking (didn't expect to, so that's a plus). It makes me feel a little less apprehensive about driving a 60 year old car in modern traffic - another plus.
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