Brake Pipe Flare

[MuddyWinny]

Hello,

While replacing the os front flexible brake hose I found that the thread on the female nut was ruined on the pipe that comes from the master cylinder (ok, from the t-piece where the pipe is split to each front side). For a new pipe that connects to the flexible brake hose I would make a female flare (i.e. where the flare cone mandrel is used without a die to create a trumpet type of end).

I just wanted to be double sure this is the right type of flare.

Vehicle is a 1986 Landrover 90

Thanks

Mark

[GBMUD]

As a rule, you want these flares for Landrovers. A single flare where you have a male thread on the pipe as on the left, a double where you have a female thread, on the right. You can usually see which by the shape of the seat it will thread onto. The double flare is made by making the single flare and then inverting it with a cone - see Youtube for demonstration videos - so that the flared part is double walled.

I nicked the picture above from http://marcossportscarenthusiasts.yuku.com/sreply/23712/Brake-pipe

Chris

[MuddyWinny]

Chris,

Thanks for replying.

The flaring tool I have describes two types of female flares, one known as a double flare that you have shown above and another made omitting the the first step in making the double flare (i.e. single step just using the cone straight into the end of the brake pipe) which is where I was getting confused.

Having dug around a little as far as I can tell this latter female fare suffers from the wall if the flare being thin and weak compared to a double flare.

The brake nuts fitted are like this (I guess it makes no difference):

Looks like I'll be making a double flare.

Mark

[Scotts90]

Yes, the fitting above requires a concave flare. On my flaring tool this involves creating a convex flare first, then flipping the die to create the concave or double flare as some term it.

[David Sparkes]

It sounds as if it may help to share an appreciation which I've only recently become aware of myself. I'm not sure why 'recently', perhaps it was because I was using an unfamiliar flaring tool, with no instructions, and found I had to work out the correct process from first principles.

Anyway, enough excuses, the appreciation I came to, or read online somewhere, was that the terms 'single' and 'double' don't directly relate to the shape of the flare (although the finished flares are different).

Rather, single and double relate to how many operations are needed to create the flare.

A single flare results from a single operation, and looks like an olive has been formed on the end of the pipe.

A double flare results from a second operation, which converts the olive to a funnel on the end of the pipe.

I think it's inherently confusing because until you accept that 'single' and 'double' relate to the forming operations, you look at an 'olive' style flare and think it's a double flare, because it flares out and then in. In fact, an olive style flare is a single flare, because it's made in a single operation.

HTH someone else, as well as me :-)

[Boydie]

Single flares are used for air conditioning connections, double flares are used on brake systems as the former are not DOT approved as they can under certain conditions, movement and vibration experienced in vehicles, flex in the union joint, these unique conditions are not experienced in static situations such as home and commercial air conditioning even though the pressures are generally far greater in air conditioning systems.

[bushwhacker]

Hello.

Any chance someone could do a techy thread on brake pipe flares ie which to make for each type of fitting.

I just do the same as what is there when they come apart. I also keep a few samples for reference but I don't know which goes with what for sure.

Thanks in advance.

[MuddyWinny]

Thanks for the replies, they have helped me understand the flare I need.

I have the following flaring tool:

It makes 3 different types of flares on different size pipes:

Single Female (concave). As mentioned above not suitable for braking systems. Formed in a single operation.

Single Male (convex), as shown on the left in the picture from GBMUD. I have used this flare on the brake pipes on the rear axle where they fit into the calipers and the T-piece. Formed in a single operation.

Double Female (concave), as shown on the right in the picture from GBMUD. As mentioned above is used as the female flare in braking systems such as connecting to a flexible brake hose and requires a two stage operation to form.

I'll be forming a Double Female for the connection to the flexible brake hose.

Thanks again for all the help.

Mark

[Scotts90]

Single flares are used for air conditioning connections, double flares are used on brake systems as the former are not DOT approved as they can under certain conditions, movement and vibration experienced in vehicles, flex in the union joint, these unique conditions are not experienced in static situations such as home and commercial air conditioning even though the pressures are generally far greater in air conditioning systems.

Not all brake systems are constructed with double flares though. Caliper, mastercylinder, wheel cylinder etc all use male fittings so require a single flare to give the appropriate mating face. These single flares are either SAE which slightly differs with an angled shoulder against the male fitting, or DIN which has a flat shoulder to fit against the male fitting. As mentioned previously it requires a 2nd operation to create the double flare.

Can't see why a single isn't DOT approved due to its use throughout the brake systems.