corroded steel brake pipes

I've been helping someone get an elderly Toyota pick up through the MOT, one failure is two steel brake pipes which run from the front to a load
proportioning valve at the rear. They are only corroded at the rear immediately adjacent to the valve and look like a right pig to fit as they run over the fuel tank. Is it allowable to cut out the corroded section , fit a joint to a short length of new tube?
AJH
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On 16/10/2018 17:37, AJH wrote:

yes
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Yes. But if you can't get at the rest of it, how can you be sure it isn't corroded too?
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On 17/10/2018 14:14, Dave Plowman (News) wrote:

Only *visible* corrosion is an MOT failure!
More helpfully, with normal dual circuit brakes the first thing you will notice is a pool of brake fluid. The next is a low brake fluid light. And even then it is a little while before you will notice a loss of braking.
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On 17/10/2018 14:37, newshound wrote:

Although that might be very nearly the last thing you notice. :)
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On 17/10/2018 14:41, GB wrote:

When I had such an unrevealed failure (in a car that had been parked up for a while in a tight space where the leak was not visible until the car was moved) I was alerted by the spongy brakes as I backed it out. And pumping the brakes gave me all the braking I needed. Subsequent to that, I was happy to drive it on the road after topping up the reservoir, driving with due caution.
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On 17/10/2018 14:55, newshound wrote:

Why bother with MOT tests at all, really? They had none of that when I was a lad. Mind you, road deaths were higher, despite having far fewer vehicles on the road.
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On 17/10/2018 15:09, GB wrote:

It's about proportionality. Dave's question was related to parts that are hard to inspect. There are two answers, firstly that concealed pipes are generally less likely to corrode because they should not be exposed to the same levels of salt and moisture, secondly that actually the consequences of pipe failure are not so great for dual circuit brakes. You get most of the benefits from the "easy wins", things like tyres, lights, windscreen washers and wipers, dampers, suspension wear, brake efficiency.
Inspection of brake flexible hoses and the exposed steel pipes are also easy.
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On 17/10/2018 15:09, GB wrote:

Because all too many people would drive dangerous vehicles. Some still do, either not bothering with MOT's, tax, insurance or getting 'dodgy' MOT's.
While an MOT only checks a limited number of things and is a spot check, it is better than nothing.
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On 17/10/2018 14:55, newshound wrote:

May be 35 years ago, I remember a 'craze' for copper brake pipes, soon followed by concerns that they were prone to 'work hardening' and failure due to vibration. Then something called, I think, Kunifer? as a replacement for steel brake pipes. Whatever it was/is called, I used it to replace some pipes on our Escort and still have a reel somewhere- it must (almost) be an antique.
I acquired a beautiful Sykes and Pickavent flaring kit which I still have.
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On 17/10/2018 19:43, Brian Reay wrote:

I used to use Kunifer too, but I was able to borrow the tools from work. This was late 70's.
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Like all such things they've come down in price. If you need to make a few pipes, the cost soon saved over buying ready mades. Maybe even more so on an old car where you can't get spares so easily.
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Decent copper would need a lot of flexing before it fractured. Not sure it would be any better or worse than steel in this respect.
Think the other is Cunifer - Cu for copper Ni for nickel. It's much easier to work and bend than steel - but might benefit from more fixing points to the chassis, etc.
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On 18/10/2018 15:19, Dave Plowman (News) wrote:

That isn't unreasonable. There are always 'stray' theories floating around.

It may have been/be Cunifer, it was a long time ago. I'm sure there is a reel somewhere in the garage/loft but heaven knows if it still has a label.
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Thing is copper pipes were common on many very old cars etc - things like oil and fuel, even before hydraulic brakes arrived.
I did wonder if the theory was based on poor quality half hard thin wall tube?
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On 18/10/2018 18:07, Dave Plowman (News) wrote:

Could be. As you say, vintage / old cars did (do) use copper for non-brake pipes. A combination of age, more vibration, perhaps thinner walls would make them more prone to failure and people read this across to copper brake pipes which were being promoted at the time.
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I'd be more concerned about safety than just passing an MOT. ;-)

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On 17/10/2018 16:45, Dave Plowman (News) wrote:

That was rather GB's point. I'd expect you to be more pragmatic. Unlike a friend of mine who spent 16 hours being Relay'd from Cornwall to Bristol with a two year old because of what turned out to be an untraceable one-off flicker of a brake warning light. Plus being without her car for a week while the AA replaced the sump and both drive shafts, having wrecked them getting the car on and off the two vehicles that they needed.
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On Wed, 17 Oct 2018 14:14:48 +0100, Dave Plowman (News)

I can't be but :
1 the corrosion is only around the valve which is on the chassis by the wheel arch and constantly sprayed in wet conditions whereas the rest of the pipe is still black paint and the bit out of sight is shielded by the fuel tank and its bump shield. I have to change the valve anyway so I expect the pipe to break when I undo the nuts.
2 the corrosion is surface rust and had I wire brushed it and painted it it would probably have lasted for a long time.
I have experienced brake failure from corroded steel brake pipes in a lovely Alfa 164 gifted me by a denizen of usenet, I wished to demonstrate the effects of ABS to my brother and chose to do it on the road by glen Nevis. A pipe burst but I had braking on the other two wheels but didn't realise how quickly the reservoir would empty with subsequent braking. I managed to get on the Corran ferry and park up the other side. In the morning a chap at a small garage, who was too busy to do the work himself, sold me a length of cunifer and the loan of his swaging kit and I replaced the pipe, topped up the fluid and drove back on the ferry and south to Surrey the following day.
AJH
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On Tuesday, 16 October 2018 17:37:51 UTC+1, AJH wrote:

You'll need a decent flaring tool to do steel pipes in situ - I have a coup le of these types https://www.machinemart.co.uk/p/draper-expert-475mm-din-h and-held-brake-pipe-f/ (note to do a double flare you need the sae version, not sure but Toyota maybe sae bubble).
I've also hear it said that a union should be used to join the pipes, as op posed to just mating a bubble and double flare in a single joint - even tho ugh manufactures often do it that way.
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