I have had an interesting discussion with an american race car builder today.

He belly laughed when I suggested using copper alloy pipe for brake lines instead of steel. I told him that UK 7 builders use copper pipe.

I don't have a problem using steel brake lines as production cars all have steel lines anyway.

We then tried to put a double flare on a piece of the 3/16" steel brake pipe How difficult is that crap! We screwed up 3 in a row.

What are peoples thoughts on brake lines, steel or copper alloy?

I had assumed I was going to use copper alloy brake lines but now I'm not sure if they are available in the states.

[Edited on 19/6/08 by liam.mccaffrey]

Steel is horrible to work with + goes rusty - kunifer is the best compromise tho' copper is softer & easier to bend - better still use stainless steel braid throughout!

Copper alloy lines are available in the U.S., just not very popular:

http://store.fedhillusa.com/

It's the way forward, I think.

Kunifer is supposed to last longer than normal copper. Manufacturers use mild steel cos they can get away with it and it's cheap (and nasty).

i had to replace the pipe for mot on my tin top on seat alhambra front to back used copper (that id got for the kit :mad
and had to flare the steel pipe under the car, the steel "production" pipe was shot in several places im actually glad it was caught at mot i really believe if i had to anchor on the pipe would have blown at the corroded part it was that bad, so now its copper all the way for me or kunifer

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Originally posted by pbura
Copper alloy lines are available in the U.S., just not very popular:

http://store.fedhillusa.com/

It's the way forward, I think.

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Originally posted by russbost
better still use stainless steel braid throughout!

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Originally posted by Peteff

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Originally posted by russbost
better still use stainless steel braid throughout!

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How is it better? It costs 5 times more and is more flexible so you get a spongy pedal.

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Copper should never be used for brake lines.
Commercial copper pipe fails through fatigue and what metallurgists term season cracking. If you have any doubts about this just ask anybody who has worked on pre-1930s cars or with industrial or marine heat exchangers.

Kunifer is the trade name for a special copper-nickle-iron alloy and which was specially developed in Scandinavia specially for use in brake lines. It was adopted in the late 1960s by Volvo and SAAB and has proved highly successful.
It is easy to work and dosen't suffer from the problems that beset coper and steel tubing, Kunifer is the stuff to use.

Steel brake pipe should be "Bundy" tubing, Bundy was a trade name for a zinc coated seam welded automotive pipe that was developed to an SAE specification because of the problems being experienced with copper in automotive applications.
Contrary to what you guys might think proper steel Bundy is actually quite good, while harder to flare and bend than copper or Kunnifer this isn't a proplem with proper flairing tools it is also fairly corrosion ressistant. However in Europe and Asia most of the bundy tubing sold and fitted as OEM is not the genuine article the zinc coating is too thin and as a result apart from corrosion problems the outside diameter of the tubing is too small causing it slip through dies when flairing.

Plastic coated bundy is also avialable this pretty good stuff but be aware the exposed metal where the coating has to be stripped back at the ends should be protected.

Braided flexible lines are used for single seater racing cars for a specific reason, a fully plumbed & bled brake system from master cylinder to caliper complete with pads could be kept in the transporter and just fitted as an instant drop in replacement.

That just leaves stainless steel tubing -- although popular in racing circles the USA avoid it is too difficult to work may require the use of non-standard compression fittings.



[Edited on 20/6/08 by britishtrident]

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Originally posted by Peteff

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Originally posted by russbost
better still use stainless steel braid throughout!

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How is it better? It costs 5 times more and is more flexible so you get a spongy pedal.

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Originally posted by chris_smith
i had to replace the pipe for mot on my tin top on seat alhambra front to back used copper (that id got for the kit :mad
and had to flare the steel pipe under the car, the steel "production" pipe was shot in several places im actually glad it was caught at mot i really believe if i had to anchor on the pipe would have blown at the corroded part it was that bad, so now its copper all the way for me or kunifer

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Copper pipe should never be used on high performance cars.

It age and work hardens and eventually becomes brittle.

I hate steel brake pipe on cars, had 2 crashes and one very scary near miss due to rusted pipes, I refuse to use it now. Not once have I had a copper pipe fail even when battered offroad in the landys.

If it is work hardening then it is mounted wrong as the pipe should be unstressed in operation, steel pipes fatigue as well. I remember years ago articles showing you how to replace rubber hoses with, just coiled up copper tube. A totally dumb idea.



[Edited on 20/6/08 by Mr Whippy]

Within reason steel provided it is not subject to strain beyond the elastic limit steel has an infinite fatigue life.

Most non-ferrous metals and alloys don't have a true elastic limit and suffer from the effects of fatigue even at low levels of cylclic stress ie vibration.

With old copper pipe if you disturb it you really should anneal it before refitting or the odds are it will split on the outside of a bend.

Just consider what happens to to copper pipe in domestic plumbing, it starts out in a coil easy to work but through working (ie bend and stretching) and time it work and age hardens and becomes hard and brittle.
As a result even a simlpe dIY job like changing a ball cock or tap and turn into quite a major plumbing job.

[Edited on 20/6/08 by britishtrident]

[Edited on 20/6/08 by britishtrident]

A few points...

Everyone is talking about Kunifer. The same generic stuff is available at Partco and is cheap.It's the only stuff they sell for brakes. Absolutely no reason to even consider copper, as dangerous as it is.

Plated steel is no cheaper than copper/nickel to us low volume users. It can be had from Pipe and Tube Group, plated and plastic coated.

Stainless steel tube is no more difficult to use, in 3/16 or 5mm, than copper/nickel, if you buy the proper annealed stuff made for the job. I use it often in the raceboats in high pressure hydraulics, and cars, and no need for special compression fittings either.

Cheers,
Syd.

It's not easy to make iron brake lines.

So Cunifer (Copper/Nickel) is my thing. Easy to handle. And making a double flange is easy with the right tools.

just to clarify,

in my original post when I said "copper alloy" I really meant cunifer. I agree using "copper pipe" is foolish.

some good info in this thread

Hi

Just a point on the assumption that a rigid pipe won't flex if correctly mounted as voiced by Whippy.
Any pipeline will try to straighten when pressure is applied, clamping can resist this tendancy but not eliminate it........so......use a material that is less susceptible to work hardening.

Regards Mick

The copper folk are very insistent about proper mounting to avoid flexing and vibration. Lots of good data here:

http://www.copper.org/applications/automotive/brake.html