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Go Back   Madabout Kitcars Forum > Mad Build Area > General Build Chat

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  #1  
Old 10th March 2015, 21:01
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peterux peterux is offline
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Default Copper or Kunifer Brakelines

It was not until Scimjim and Robin (aka Martinclan) posted concerns about Copper brake and fuel lines, that I was made aware of the controversy surrounding pure copper brake lines.
I've started this new thread so as not to hijack Robert's Marlin Berlinetta's restoration thread.
Robin posted this comment....

Quote:
Originally Posted by MartinClan View Post
Just catching up with this thread :-)

Copper is generally frowned on for fuel lines (and brake lines) as it work hardens with vibration and then cracks. I believe thats the reason it is not accepted by the IVA testers. I used Kunifer for both brake and fuel lines. Its an alloy of copper and something and doesn't suffer so much from the work hardening issue.

Cheers, Robin
So I've pulled out this issue in a separate thread to draw others attention to the issue.
It does seem to be a very controversial subject with some folks seriously falling out on some forums! Just try Googling "Copper brake lines illegal" and read some of the other forums debates on his subject. (I hope we will have a much more typical MAKC discussion )

I used 'pure' Copper brake and fuel lines on my Marlin Sportster that was SVA'd in 2008 and passed with no comment about the use of Copper. Either the inspector didn't have an issue or maybe thought they looked like Kunifer due to the length of time it took to build the car

I have already discounted using Copper for the fuel lines due to the issues of Ethonal being added to petrol thanks to European legislation (but that's another can of worms...), but I was planning on using copper brake lines as copper is easier to flare than Kunifer. I have even recently bought a reel of the stuff from Halfords when I was in there the other week and saw it at a very reasonable price.
http://www.halfords.com/motoring/gar...pe-tubing-25ft

I remember that I bought the copper pipe for my Marlin from a company specialising in braking components called Automec, so I thought I'd take a look at their website and found that they sell both types of tubing...

http://www.automec.co.uk/collections/brake-pipe-coils

...and seem to make the point that their copper pipe is " high quality thick walled copper tubing is manufactured in Great Britain and specifically designed for use with brake systems." (and it's over double the price of the Halfrauds stuff)

The Kunifer seems to be the preferred choice by the automotive industry.

But from my limited research it does seem that Copper pipe for brake systems is banned in some parts of Australia, New Zealand and possibly the USA?

I think for the price a reel of Kunifer I'll ditch the copper and use Kunifer, if nothing else but to avoid an unnecessary fail at the IVA test.

I hope this is of some interest to other forum users.....


....peter
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  #2  
Old 10th March 2015, 21:40
8 Valve Ed 8 Valve Ed is offline
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Thanks for raising this Peter, I think we do need to be aware, sometime we beaver away in our own little bubble blithely unaware of issues which may have profound consequences.

The copper pipe I am using for the brakes is designated brake pipe with the appropriate standard E? marked along it's length. I have noticed when doing MOT rectification that the steel ends tend to corrode like crazy in the presence of copper. I worked on a Land Rover last year and the front female nuts connecting the copper pipes to the flexies had eaten right through to the threads. I had never seen a nut so badly corroded. (I assume) it had also caused the swaged retaining collar which retains the rubber brake pipe onto it's fitting to corrode away completely, the rubber brake pipe pulled off with little or no effort. Generally the copper pipes are not reusable unless they are very recent, I frequently replace them if they need removing for any reason.

I haven't noticed any difficulty flaring the ends of Kunifer, although I have noticed the part which has been clamped is almost impossible to bend close to the nut, which can be an issue if space is at a premium. I use a Sykes Picavant flaring tool.


As for fuel pipe, I accept the 0.6mm wall thickness is somewhat thin but my concern with plastic/nylon it it's vulnerability to being cut and melting in a fire.

I have actually experienced the former in an Astra Van, while driving on a mission near Oxford, I ran over an object in the road which flipped up and cut my main diesel pipe clean in two. Diesel all over the road and the engine dead, 250 miles from home with almost no tools. I taped the two ends together with gaffer tape, and made it to Benson Lock where a boat yard kindly gave me a foot of rubber hose to push onto the two ends of my main feed pipe. I lost a lot of fuel but I was able to get home under my own steam.

On the Berlinetta I have routed all my critical pipes and wires where they are not likely to suffer that sort of damage, but I am still not keen on plastic fuel pipes.

To add another dimension to this discussion, perhaps slightly OT, clutch hydraulics; There is a school of thought that the clutch pipes need to be 6mm OD. The only justification I could find was that 5mm pipe can inhibit (slow) the engagement of the clutch and cause judder under certain circumstances. Once upon a time all brake pipes were " steel pipe, I think the move to 3/16" was to make bleeding easier and to make savings for the manufacturers.

I have rabbited on quite enough...
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  #3  
Old 11th March 2015, 16:01
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MartinClan MartinClan is offline
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Hmm. Maybe the issue is that there are different grades of copper. I noticed that the Automec website specifically mentions "soft" copper for brakelines.

I am going to ask my metal expert....

Robin
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  #4  
Old 12th March 2015, 08:50
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MartinClan MartinClan is offline
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There's an interesting article here that sums the advantages of cunifer (and spells it correctly - oops).

http://www.brakeconnect.com/cunifer-brake-line

Cheers, Robin
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Old 13th March 2015, 19:39
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I also found this article which may be the source of some of the information in Robin's article above.

http://www.copper.org/applications/a...ube/brake.html

The way I read it is that it doesn't actually say that pure copper is bad, just that Cunifer has better strength and fatigue characteristics.

I think the key paragraph is ....
"Copper had been proved since the early days to have many good attributes. It was easy to bend and had very high corrosion resistance, but there was concern about its low corrosion-fatigue strength. When copper-nickel was introduced, it displayed corrosion resistance similar to copper, higher general strength and better fatigue strength. Good formability allows ease of flaring and bending, and although the metal cost is greater than that of steel alternatives, copper-nickel is very attractive in view of its extra life, trouble-free installation and safety/reliability characteristics."

But I've still not found any examples of copper pipe failure?


...peter
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Old 13th March 2015, 21:57
8 Valve Ed 8 Valve Ed is offline
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Quote:
Originally Posted by peterux View Post

But I've still not found any examples of copper pipe failure?

...peter
I don't think you will Peter, however I remain convinced the copper causes a sacrificial corrosion of other critical parts of the system. I don't have a photograph of the corroded crimped retainer from the Land Rover brakes I mentioned above, I did keep one of the nuts. The other nut I recovered, I gave to the owner as a reminder of the need for occasional checks. That nut was worse than this one. The male threads were visible through the sides of the nut. When it was removed, you could see through the series of slits caused by the threads. I have seen some rusty bolts in my time but never as bad as these, not on a working vehicle anyway.

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