49 replies to this topic

[gav]

I think it is a bit of a worry that you are carrying out repairs on safety related components with little knowledge of the basics.

No matter which material the pipes are made of the correct pipe flair, single or double, must be used.

I suggest if you cannot identify the pipe flair that is required for each application then STOP and go no further until you can.

Steel, copper or kunifer materials are perfectly suited for brake pipes, and normally copper or kunifer are the aftermarket preferred material.

Copper is a bit "soft" and can sometimes be difficult to get straight on long runs and maybe not so pleasing to look at against the more rigid nature of kunifer.

Until you can identify which flair is required go no further, then recheck your earlier work and amend as needed.

 

That is incorrect, you shouldn't be using a single flare on Kunifer lines, they are much softer than steel.

[sonscar]

So concave pipe flare fits into concave fitting?Does not seem right to me.I have always matched the flare shape to the fitting and it has always worked.I will continue to use my method.Steve..

[Ethel]

That's a handy picture for showing the differences between SAE & DIN flares. The obvious one is the flat back on the Metric DIN

[mbolt998]

 

 

You should be double flaring them if using Kunifer lines, every brake pipe we sell is double flared, a lot of confusion comes from comparing the original steel lines to Kunifer lines.

I'm using copper lines (which are also apparently deadly but what MiniSpares sell so they surely can't be that bad). The flaring tool I have basically puts a dome on in the first pass, and then a little indentation into the dome if you repeat with the other end (this is a "double flare"). Are you saying I want the double flare even though all the (mostly steel) lines that came out had bubble flares? How is that double flare going to match up to the presumably concave shape on the other side of the unions?

 

 

 

No that is incorrect, we (Minispares) only sell Kunifer lines not Copper.

 

Sorry my bad, I might not have got it from MiniSpares. But it is meant to be brake line (I guess copper/nickel rather than kunifer).

[Nial]

"But it is meant to be brake line (I guess copper/nickel rather than kunifer)."

 

I think Kunifer is coper/ nickel, and AIUI it's what you want .

[mbolt998]

You should be double flaring them if using Kunifer lines, every brake pipe we sell is double flared, a lot of confusion comes from comparing the original steel lines to Kunifer lines.

So just to be clear: the flare you're putting on all pre-made Kunifer lines sold by MiniSpares is a standard SAE double-flare? If this is the case then that's good enough for me. I won't redo my double-flares.

[mbolt998]

"But it is meant to be brake line (I guess copper/nickel rather than kunifer)."

 

I think Kunifer is coper/ nickel, and AIUI it's what you want .

So confusing. Lots of people saying "never use copper brake lines or you will die" but the apparently coppery lines that most places sell (and that I think most people use who are doing their own lines) aren't pure copper anyway, but some suitable alloy.

[Earwax]

Kunifer  -- CUNIFe  ( Copper Cu   Nickel Ni  Iron  Fe) - and manufactured with no seam or to withstand a large pressure-  is sold as brake line  - that is my understanding anyway.

 

The confusion is there for me still too, but I am not skilled or confident enough to offer a definitive answer ( these are vital bits for safety)

 

I would take your machine and your pictures and maybe some line down to a brake specialist who does stuff on old cars for peace of mind

[gav]

 

You should be double flaring them if using Kunifer lines, every brake pipe we sell is double flared, a lot of confusion comes from comparing the original steel lines to Kunifer lines.

So just to be clear: the flare you're putting on all pre-made Kunifer lines sold by MiniSpares is a standard SAE double-flare? If this is the case then that's good enough for me. I won't redo my double-flares.

 

 

I think it's referred to as the universal double flare but yes every pipe we sell is the same.

[GraemeC]

Usually pre-made kits from proper suppliers are the correct grade of tube - usually made by Automec.

Rolls of tubing are sold by some and these can be either copper or copper/nickel (Kunifer (which is a brand name)).  There is usually a price difference, but not much.  Kunifer is a little harder to work with though:

https://www.carbuild...arts-brake-pipe

 

The reason copper is generally frowned upon is that it work hardens.  So if it is subjected to vibration it can become brittle and fail.

 

Generally (but not always!) for a male threaded union you need a bubble/single flare and for a female threaded union a cone/double flare - I know them as single and double as they either need one operation or two on my flaring tool.  Again, different tools may be different.

*edit* CBS sell a very similar tool to the one I have and the instructions show the different types of flare:

https://www.carbuild...pe-flaring-tool

Edited by GraemeC, 14 October 2022 - 08:16 AM.

[mbolt998]

Usually pre-made kits from proper suppliers are the correct grade of tube - usually made by Automec.

Rolls of tubing are sold by some and these can be either copper or copper/nickel (Kunifer (which is a brand name)).  There is usually a price difference, but not much.  Kunifer is a little harder to work with though:

https://www.carbuild...arts-brake-pipe

 

The reason copper is generally frowned upon is that it work hardens.  So if it is subjected to vibration it can become brittle and fail.

 

Generally (but not always!) for a male threaded union you need a bubble/single flare and for a female threaded union a cone/double flare - I know them as single and double as they either need one operation or two on my flaring tool.  Again, different tools may be different.

*edit* CBS sell a very similar tool to the one I have and the instructions show the different types of flare:

https://www.carbuild...pe-flaring-tool

Thanks! This clears more things up. The lines I have are copper not kunifer based on the illustrations in that page. Kunifer is a yellow more bronze-like colour. Copper is copper-coloured.

 

Based on other comments in this thread I think a lot of people do what you do-- "half double" SAE flare if the thing it's going into looks like a bowl not a volcano (all the fittings I've looked at are bowls). I have no doubt this works well. But you can also do an SAE double flare and this will also work fine into the same fittings: it's what MiniSpares do on all their premade kunifer lines. Since that's what I've already done on a bunch of lines I will leave them in for now and see what happens when I start adding fluid and trying to bleed it and get pressure.

[Ethel]

Just match them to what you're are mating them with:

 

Double or "trumpet" flares go with make ends of hoses. Single "outty" flares go into machined holes with a concave bottom - be sure they don't screw all the way in before they nipped the flared end against the bottom of the hole.

[gav]

Just to reiterate I wouldn't use a single flare with any Copper/Kunifer pipe...

[weef]

I would be interested in reading the technical explanation as to why the singe flare as opposed to the double flare is not suitable for the copper alloy type brake tubing but is suitable for steel tubing to help my understanding.

Brake tubing no matter which material it is made from must reach the standards set out in BSEN 12449 as regards sizing, cleanliness and make up and there are similar standards for the flare end sizing.

The copper alloy type tubing provides superior reliability and assures both the manufacturer and vehicle owner of improved durability and long life of the braking system.

I do not think the manufacturers of the tubing and the associated flaring tools go to all the trouble of meeting these standards if the end user is just going to make up pipes with whatever flare profile they fancy, and why supply flaring dies for both the single and double flare ?.

Regarding the work hardening of the copper type tubing it is an MOT requirement that the pipe must be clipped in as per original and by doing this will help negate any work hardening.

If you have the facility to make your own pipes replicate the end that the vehicle manufacturer used, I am not too sure how the "universal flare" works other than when tightening up the tube nut it somehow crushes the "flare" to the profile it is presented to. 

[mbolt998]

Just to reiterate I wouldn't use a single flare with any Copper/Kunifer pipe...

Why not? (Assuming by "single flare" we mean doing only the first part of an SAE double flare and so ending up with something that is a lot like a bubble flare). Lots of people are saying they do this and it's fine.