16 replies to this topic

[mister bridger]

I've recently replaced all my brake pipes on my mk1 with copper but have just read that they are banned almost everywhere in the world except the UK. What is the issue and have I got to do it all over again?

[zinzan]

Straight copper hardens and goes brittle, I think. The Mini ones are a copper-nickel alloy I think. My mechanic just told me he won't fit the alloy ones either as he feels they're still not that safe (?) and is doing up stainless steel instead.

[jaydee]

I can bet you havent got copper brake pipes but cunifer brake pipes, which is what on market today for minis, and thats safe.

[tiger99]

Stainless will make mincemeat of the average flaring tool! Apart from that minor problem, it should be very good.

The problem with copper is that it does not hava a fatigue threshold, unlike steel, and therefore under cyclic stresses due to vibration, and even more importantly, pressure cycles due to actually using the brakes, it fatigues, and fails. It may have a static burst pressure of 6000 psi, but it will not take all that many pressure cycles to 2000 psi, very hard braking, for it to fail. Certainly not the 10 million cycles to which production brake systems are tested. Flaring and bending count towards the accumulated fatigue damage.

Even worse, the criminal suppliers of that junk are keen to pretend to be selling something reputable and safe, so they often quote a BS standard. One of the quoted standards was, when I checked it, nothing to do with either copper or pipes, just a number they had picked out of the hat. Another was for "copper pipe for general use", and we have a copy at work so I checked it and it was clearly unsuitable for brake systems. In short, there is no BS or other standard anywhere in the world for copper brake pipe, because technically (and legally, as certain suppliers are going to find out when they are sued out of existence), there is no such thing as "copper brake pipe". There is, however, microbore central heating pipe, which is what has been sold as brake pipe.

On the other hand, copper-nickel alloy C70600 is, in the appropriate diameter, fully specified for brake use and has a more than adequate fatigue capability, provided it is installed and supported properly. It is good for hundreds of millions of pressure cycles in a car. It is used by most of the top-end manufacturers, military, etc, and is approved to proper standards, SAE J527, ASTM A254 and SMMT C5B (Society of Motor Manufacturers and Traders in the UK), ISO 4038 and SAE J1047. These standards mostly are about vehicle braking systems, so if you use cupro-nickel, aka Cunifer or Kunifer, you are using a properly specified and approved product.

Edited by tiger99, 13 October 2012 - 03:18 PM.

[tiger99]

jaydee,

Most of the suppliers are still supplying serious quantities of copper. They charge more for cunifer. That will only change when they are faced with a criminal prosecution, which is inevitable as it is only a matter of time until someone is killed.

[tiger99]

Oh, and if anyone wants to know what they have, you can tell very easily by the colour, when new at least. Copper is basically a red colour and shiny, cunifer is reddish but with a distinct greyish tinge and much duller. Bend them between your fingers and the diffecence is even more obvious, cunifer is hard but still workable, copper is soft until it work hardens, before it fails.

Edited by tiger99, 13 October 2012 - 03:17 PM.

[jaydee]

Minispares pipes are actually cunifer, cant comment on ebay crap, but if what they sell is just copper, they're criminal

[tiger99]

Actually, I know for a fact that Minispares are supplying copper, or were quite recently, and their web site confirms that.

[midridge2]

http://www.brakepipe...t&product_id=83 and http://www.brickwerk...uemart&Itemid=3

[Old Bob]

Never too old to learn something new! I have always used copper pipe believing it was the right thing for the job. Never had a pipe fail either but I have probably never exceeded the failure cycle rate.

Just don't understand why this situation is not better understood or regulated.

Bob

[tiger99]

midridge2,

Your links actually prove the point rather well. The first one is copper, to the appropriate BS for copper, and will withstand 8000 psi at least once, but that spec is the one which is specifically not for brake pipes, i.e. just "copper pipes for general use", and it will not stand very many pressure cycles. The second one is to a later BS spec, which covers much the same thing, and its rated pressure, 1841 psi, is LESS than what a heavy-footed driver will achieve.

The people selling that stuff are criminals, and will be found to be such in court one of these days, but probably only after people have been killed.

[[email protected]]

Actually, I know for a fact that Minispares are supplying copper, or were quite recently, and their web site confirms that.

All our kits are cunifer, as Jaydee correctly says

[minirage]

wait Ive just renewed the brake lines on my rebuild in copper which I made up myself, so you saying this is wrong???

[tiger99]

Yes, it is downright dangerous, and you should replace them all with cunifer as soon as possible.

[minirage]

hmm may explain all the puddles on the garage floor under the mini