Brake pipes

Ask the Yanks. As they have commonplace access to pure copper aircon pipe, this is a common bodge. The problem is that pure copper work hardens and you _will_ see brittle fractures around the flares. Put your foot down hard and you can pop a pipe clean in half.

If this was kosher "copper" brakepipe, it wasn't pure copper but it was

10-15% nickel alloy. This looks and handles like copper, but it doesn't have the cracking problem.

IMHO the real KuNiFer (the three layer stuff) is the worst of all worlds. A pain to flare by hand or to fit, and you can still get rust damage on it. I always use the correct copper alloy.

You seem to be under a misapprehension. Kunifer pipe is is made from cupro nickel. An alloy of copper and nickel. For brake pipes it's basically 90% copper, and 10% nickel.

As far as flaring is concerned, I've completely replaced all the brake pipes on a couple of cars, and made up many more individual pipes using Kunifer.

The flaring was the easiest part of the job, but then I have decent flaring tool. Bought s/h about 15 years ago at an auction selling off the contents of an independant garage that had gone bust. Getting the lengths, bends and runs perfectly right was more difficult.

And no way does cupro nickel rust. It is highly resistant to corrosion, which is why it's one of the favoured alloys for marine hardware, inc propellors for smaller craft. Tugboats, fishing boats etc.

I don't know what you mean by "correct copper alloy". AFAIC cupro nickel 'is' the correct copper alloy for brake pipes. Kunifer is just a trade name for one particular make. There are other Co's that make similar spec cupro nickel brake piping. Mike.

I just got a catalogue in the post from Demon Tweeks. They sell parts for motor sport. Including pure copper pipe for brakes. If it were such a problem surely scrutineers wouldn't allow it?

The scrutineers I came across were quite easy to fool if you wanted to, both private circuit and RAC

Maybe the scrutineers are not aware of the potential problem. Or ignore it if the pipes look comparitively new, because in general, new copper pipes don't suddenly fail.

There is nothing wrong with using copper pipes over the short term, and if they have been fitted and supported correctly they can last for years. In a sense that 'is' the problem. They are like a time bomb waiting to go off.

Dependant upon how well they are fitted it could take as little as weeks up to years before they fail. Maybe not at all before the car is scrapped.

Thing is, you can't predict when a copper pipe is likely to fail. Unlike Bundy tubing which can be checked for rusting and other signs of deterioration, copper shows little signs at all. Chances are that if and when a copper pipe fails, it will be when you least expect it. Probably when you most need your brakes to stop or slow down quickly.

I think pure copper brake pipes should be made illegal, but I suppose that since there are no figures to show it's not a suitable material, or any public awareness of the potential danger, the likelyhood of that happening is zero.

A simple experiment to prove the point about the unsuitability of copper piping. Try bending piece of domestic copper pipe that's years old and see how hard and brittle it is compared to a new piece. Mike. .

I really can't see how work hardening presents a problem. On every car I've owned the brake pipes are firmly clipped to the 'chassis'. Anywhere there is movement is accommodated by flexibles.

Not a good example. Modern thin wall domestic copper pipe is half hard already - and doesn't take kindly to bending unless specialised techniques are used. Older stuff was easy to bend with a spring. And any of the older stuff I've reclaimed still bends easily.

Maybe it wasn't that old. In any case I doubt it bent as well as the new stuff. IME it is harder than new stuff, and that is purely from it age hardening. Throw in weathering, vibration and the possible flexing that it can be subjected to if used for brake pipes, and you have a potential problem.

Given that other opinions of copper brake pipes are similar to mine. I cannot see the point of using it, when cupro nickel piping without any apparent problems can be used instead, and when the difference in price can be as little as £1 more for a 25ft roll of 3/16" Kunifer. £8 as opposed to £7 for copper piping. £1 is not much to pay to have no concerns about durability. Mike.

Dave Plowman (News) ("Dave Plowman (News)" ) gurgled happily, sounding much like they were saying:

Never owned a 2cv, then? Movement is accommodated by flexing coils of metal hydraulic piping. Same with accommodating engine-to-body movement of the main pump pressure pipes on hydraulically suspended Cits.

Oh I agree that there's no point in using copper since the alternative costs so little more - but I have a suspicious feeling those who go on and on about copper for present day brake pipe use failing are simply jumping on a bandwagon. I have used it in the past without problems - nor would I really expect there to be.

Copper in the home is often badly supported and can vibrate a great deal too - but I've never known it to fracture through this. And if it could work harden and fracture through poor support on a car, so I'd guess would cupro-nickel - it would simply take longer. No material on earth is immune from fracture due to flexing.

Ah. Then of course a more suitable material is needed.

Could account for the poor reputation, then?

But on every car I've owned there is no movement planned into the 'solid' brake pipe runs - apart from when a component is removed.

& "No Copper brake lines" is a fairly common motorsport rule.

Where are you buying your copper then? Everywhere I've seen recently is at least twice that - due to the chinese, coper is now £20k a tonne!

Mike.

Personally I wouldn't use it. You must have seen the state of some distributor capillary pipes on older cars. A couple of the older machines at work had copper lubrication pipes some of which broke simply because they had to be bent slightly to release them after the unions were unscrewed.

Agreed, but if the time it takes is longer than the average life of a car, does it really matter?

All I'm really saying is that I don't think the risk of using copper piping can be easily dismissed. Not because I'm jumping on a bandwagon, but because I've seen what can happen to copper piping myself.

The fact is that copper does corrode, especially when exposed to weather. It's a slow process, but given time crystallised copper salts form, giving old copper it's greenish colour. If left long enough those copper salts go deeper and deeper into the metal substantially weakening it. Alloying copper with nickel effectively stops that corrosion as the nickel acts as a corrosion inhibitor.

I've never seen those affects on a car admitted, but I see no reason to suspect the effects of ageing, vibration, and particularly weather, not to mention the high pressures involved, can do anything but hasten it's potential for failure if used for car brake lines. Mike.

Usually a relatively long unsupported run. But I've not known one fracture in use. Or those to the oil gauge - and that had to take up engine movement. You just put a couple of coils in it.

If old presumably you didn't know how often they'd been flexed by removal?

My point is brake pipes don't get flexed.

Heh heh. I started this thread because the car my brother's just bought has needed new brake pipes at 7 years old. And under 50,000 miles.

I've a feeling in my bones it would last *far* longer than the rubbish makers fit from new. ;-)

Ah - right. Seems strange you can buy it if it's so not suited to the job.

Possibly, but I wouldn't like to put it to the test. My '94 525i and '97 528i appear to have perfect unrusty brake lines at about

180k on both. I took the opportunity to look around at their last MOT's while they were on the hoist. OTOH the '98 528i which has only done 112k, received a caution for a rusty brake line to the back axle, and a rusty petrol pipe in the same area. Not serious, even the MOT guy reckoned that a good spray with something like Dinitrol or Waxoyl, should be enough to check any further corrosion, but it just goes to show that mileage is no guide as to the condition of brake pipes.

If I were in your brothers position, would certainly replace the pipes with Kunifer ones. Might cost a few quid more but it would be a fit and forget solution. Might even help with the resale to be able to say to a prospective owner that he need never worry about corroded brake pipes. Mike.

Competitions break lots of things that are rarely a problem on road cars :-)