Correct Flare type for Bundy lines

[pharriso]

I am building up my new chassis & am at the stage of making up Brake lines. I have purchased 3/16 bundy from the UK & have 3/8-24 male & female fittings from a variety of sources including FedHill here in the US - https://store.fedhillusa.com/britishgirling-316475nutsandfittings.aspx

I purchased the Blue Point TF528E Flare & Double Flare tool & was quite happily putting double flares on both male & female fitting ends.

Coincidentally I just overhauled my Front brake calipers & noticed the small pipe had a diffferent form on the male fitting end of the short pipe - looks like what FedHill refer to as "British Girling nut with old style bubble flare" on page 1 lower right hand corner of the attached document.

FedHill_common flares6.pdf

(745.97 KiB) Downloaded 627 times

I've done a lot of research trying to confirm this, best document seems to be this info from Dave Bean's catalog:

DaveBean_BundyConnections.pdf

(665.96 KiB) Downloaded 444 times

So can someone please confirm or correct:
1. Male fittings use a Bubble flare,

2. Female fittings get the double Flare

Fortunately I've only made one (1) male fitting & looks like the bubble flare can be made with my tool - Like this: - https://www.youtube.com/watch?v=HVbHk0kkX8k

[Andy8421]

Phil,

I think your 'male gets a bubble' is correct, I can't think of a fitting on the Elan where the opposite is true.

I would bring your attention to the advice that 'serrated grips should not be used' in the Fedhill document. I used to have the same type of flaring tool you have, but I was unhappy with circular marks left on the pipe by the serrated grip. I had a pipe fail, and I managed to convince myself this was due to the stress concentration caused by the indentations left by the tool.

I paid up for a 'proper' tool with split dies, and while it still generates faint marks, they are longitudinal not radial. It produces great flares every time.

Andy.

Edit:

I have a similar tool to this, bought a few years ago at a much lower price. The picture shows the smooth, split dies.

https://www.demon-tweeks.com/uk/automec-universal-flaring-tool-s-caft100/

[Mike Ostrov]

Hi, Phil. A bit late for you, but for decades I have bent all the hard lines for my Climax Elites in stainless tubing, as I also fabricate the three AN -3 stainless/Teflon lined flex lines. All the fittings are AN/JIC at 37 degrees and only single flare or bubble flares as needed. The tubing does stay bright and shinny, so far. All flex brake lines are tested at 1500+ psi.as the .70 bore brake single master cylinder generates 800 -1000 psi under normal (non panic) operating conditions.

Same for my two Elite/Elans including the -4 oil pressure line which I cover in black shrink tube.

Fuel lines for both my Weber and Stromberg Twin Cams are done in -5 or -6 AN.

A bit more effort, but easy to remove and no banjo fittings anywhere, as they do not work for me!

Hope this helps someone next time.

Cheers. Mike.

[Certified Lotus]

Phil, I?m on my fourth Lotus restoration and I am currently replacing every single hydraulic line on the 72 Europa I?m in the midst of restoring. I?ve owned a number of flare tools over the years and finally broke down to buy a K Tool brake tube flaring tool KT-70081 when I started restoring my Elan S1. Next to my media cabinet, it?s the best tool I ever bought. You can make any type of flare effortlessly and correctly the first time. By the way, I only use copper nickel brake lines, they are easy to bend to the desired shape and have a long life once in place.

[pharriso]

Thanks for the recommendation on the Tool Glen.

You can make any type of flare effortlessly and correctly the first time.

What type flares do you put on the male & female connections?

[nmauduit]

Phil, I?m on my fourth Lotus restoration and I am currently replacing every single hydraulic line on the 72 Europa I?m in the midst of restoring. I?ve owned a number of flare tools over the years and finally broke down to buy a K Tool brake tube flaring tool KT-70081 when I started restoring my Elan S1. Next to my media cabinet, it?s the best tool I ever bought. You can make any type of flare effortlessly and correctly the first time. By the way, I only use copper nickel brake lines, they are easy to bend to the desired shape and have a long life once in place.

same here, excellent tool (I recall I purchased mine via Eastwood - no affliliation), I use mostly stainless tubing, including larger diameter on big american cars (fuel lines, hydraulics...) : it's very comforting to be able to rely on an exact cut after you've spent some time bending a pipe just right...

[Certified Lotus]

Thanks for the recommendation on the Tool Glen.

You can make any type of flare effortlessly and correctly the first time.

What type flares do you put on the male & female connections?

Phil, I am very careful to duplicate what ever flare was originally on the fitting taken off. All my cars have never had the lines and fittings replaced from the factory and I document and copy what ever flare was used. I have found that your male and female fitting of bubble flares is correct.

[pharriso]

I have found that your male and female fitting of bubble flares is correct.

Hmmm don't want to beat this to death (q plates come to mind)...

But I am saying Bubble flares on male fittings... Double flares on females....

You are saying Bubble flares on both Males & Females?

[Mike Ostrov]

Having fabricated numerous brake/clutch lines over the past 4 decades in a variety of metals, I have found the simplest way to determine the type of male end flare is to examine the female internal design.

The majority are 3/8 x 28 tpi. .We have: master cylinders, alloy or brass T or straight connectors, brake calipers and stop lamp fittings.

Most internal female configurations are; 1. an inverted cone shaped bottom, usually at 45 degrees, hence a bubble flare is appropriate. 2. a "volcano" bottom, like a small raised circle in the middle which will require a double flare to fit over the "volcano" .portion.

Many brake calipers use banjo fittings with either alloy or copper compression washers or a single compression washer on the end of the rubber flex line..

Early stop lamp T fittings used a Lucas bull nose type of switch which bottomed out if the female fitting is an inverted cone. Later switches used a single compression washer and some can use NPT threads.

Keep it simple, match the male and female requirements and pressure test each joint with compressed air in a bucket of water or a spray of soapy mixture at 100 psi or more. Any leaks will be visible.

Just had to split a side entry front caliper. Even at 1200 psi hydraulic pressure one piston did not move, even after repeated soaking and heating cycles. Sadly, rust can be an excellent adhesive.

Cheers. Mike.

[pharriso]

Having fabricated numerous brake/clutch lines over the past 4 decades in a variety of metals, I have found the simplest way to determine the type of male end flare is to examine the female internal design.

The majority are 3/8 x 28 tpi. .We have: master cylinders, alloy or brass T or straight connectors, brake calipers and stop lamp fittings.

Most internal female configurations are; 1. an inverted cone shaped bottom, usually at 45 degrees, hence a bubble flare is appropriate. 2. a "volcano" bottom, like a small raised circle in the middle which will require a double flare to fit over the "volcano" .portion.

Mike, think you'll find they are 3/8-24tpi... All the 3 ways I have have the inverted cone shaped bottom - so need bubble flares.

Based on comments on here regarding the use of flaring tools that mar the brake pipe & a recent rear brake pipe failure whilst racing I will buy a split die flare tool.

Even more research found this link - http://www.dimebank.com/BrakePlumbing.html from which I quote "British cars have a bubble flare (aka Girling flare) backed up with a male swivel nut or a 45 degree double flare backed up with a female swivel nut."

Just to add to my frustration / confusion the 3/16 Kunifer that I bought in the UK came with what was meant to be 3/8-24 male & female fittings. Turns out they are all 10mm x 1, which will assemble onto flex brake pipes with male 3/8-24 thread, ask me how I know!

[Certified Lotus]

Here are photos of the correct flares for each type of fitting as per the factory:

Hope this helps!

[pharriso]

Thanks Glen, that confirms things, a Male with Girling "Bubble" flare & the Female with the 45 degree double flare; the latter with some serious brake pipe corrosion!

I know way more now than I ever wanted to know about Brake flares...

[Certified Lotus]

Nothing like being an expert Phil

As you noted, there was a very good reason why I replaced all the hydraulic lines on my Europa......