Brake pipe temporary repair ?

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ellevie
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Brake pipe temporary repair ?

Post by ellevie » Sat Jun 10, 2006 12:14 am

As a result of replacing my trailing arm bearings, the brake pipe on one side near the calliper has started to seep at a particular rust spot. The condition of the pipe away from this spot is not too bad. I have ordered a replacement pipe from Citroen, but it will take a few days. Does anyone know how to make a temporary repair to the pipe ?
David

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AlanS
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Post by AlanS » Sat Jun 10, 2006 12:28 am

If there's not too much rust and general grot around or on it, cut the pipe, clean up, sleeve and silver solder with brown tip silver solder.
It'll probably last as long as the new one will.
Did it on a CX once when the handbrake cable rubbed the HP pipes through just below the firewall (a common CX problem) and being out here it seemed an impossible task to be able to get a new one, so took the busted pipe to a mate of mine who did hydraulic repairs to see about getting a new one tailor made. He just took one look, reached for his pipe cutters, cut a bit of pipe about 30mm long, cut the original, cleaned up with sand paper and a wire brush, slipped the sleeve on, silver soldered it and sent me on my way all within a couple of minutes.
Pipe was still perfect when the car was written off about 100K klms+ later.


Alan S
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ellevie
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Post by ellevie » Sat Jun 10, 2006 12:41 am

Thanks Alan,
This sound pretty good. Is the sleeve a piece of copper pipe of a larger diameter ? What equipment do I need to do silver soldering ?

David
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AlanS
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Post by AlanS » Sat Jun 10, 2006 2:52 am

I suppose you could use copper, just remember if you do, to fan the flame so you don't end up with one metal getting hotter than the other.
Ideally, oxy acet is the go, but I have also done them using an LPG blowtorch.
It is important to get the correct grade of silver solder. Over here it's referred to as "brown tip" (all sticks are colour coded at the end) which is a grade suitable for steel or copper to steel. If you go to buy it, ask for one suitable for "ferro" and the guy at the shop should point you in the right direction.
You'll also need a jar of flux to go with it.

Something like this will do the job easily.

http://cgi.ebay.com.au/YANES-BLOWTORCH- ... dZViewItem

or one of these:

http://cgi.ebay.com.au/IRODA-Long-Nose- ... dZViewItem


Alan S
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ellevie
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Post by ellevie » Sat Jun 10, 2006 8:51 am

My soldering experience is limited to electronic circuit board soldering and I don’t have any welding experience. Are sleeves of various sizes made of appropriate material commonly available for this type of soldering ?

I think I would now be pretty cautious about helping someone to replace their trailing arm bearings due to the risk of brake pipe failure, unless I had a suitable “way out” prepared in advance.

David
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AlanS
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Post by AlanS » Sat Jun 10, 2006 9:02 am

Wouldn't it be just as easy to whip the pipe off and get someone with the right welding gear to do a cut and sleeve job on it?
Providing you marked it so any bends were pointing in the right direction, it shouldn't be all that hard to do.



Alan S
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ellevie
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Post by ellevie » Sat Jun 10, 2006 10:00 am

I'll be happy enough if whipping my new pipe back on proves to be simple. The pipe seems to disappear up behind something in the middle of the car --- I hope it will be easy enough to trace its route.

So what would you use for a sleeve ?

David
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AlanS
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Post by AlanS » Sat Jun 10, 2006 10:13 am

I've got to do the arm bearings on my estate soon, but from memory I think you undo those 16mm bolts that hold the sway bar in and there's a saddle that fits under the edge of the clamp. From there I think it goes to a connection in the centre of the rear axle which isn't all that hard to access.
As I say, it's been a while since I was poking around under there and last time I was pulling exhaust pipes and driveshafts off as well as delving into the mysteries of the dreaded auto transmissions, but I think that's somewhere near the mark on what needs doing. No doubt, someone whose been there more recently than me will refresh all our memories on this.:wink:
As regards what we used, from memory I think we just simply used a slightly different sized steel pipe, reemed the inside edges out and sanded the faulty bit prior to cutting and then pushed one inside the other.
One trick I've used in the past that often works well, is to use an imperial sized pipe as a sleeve for a metric one as the differential usually is about right for the job.

Alan S
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ellevie
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Post by ellevie » Sat Jun 10, 2006 10:47 am

The standard UK brake pipe is 3/16" or 4.76mm with an inside diameter of 3.34mm which is just too small for the Citroen 3.5mm pipe, unless it could be expanded by heating.
David

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Post by AlanS » Sat Jun 10, 2006 11:17 am

I think you'll find, cleaned and sanded then heated, it should be a nice tight fit and the silver solder would then only be used as much as a seal as it was a way of retaining it there, after all the difference of approx .3 of a mil should be easily taken up if the above is followed.
Option #2 of course is to swage the one end of the pipe and solder it after it's fitted over the other.


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ellevie
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Post by ellevie » Sat Jun 10, 2006 1:30 pm

Well I've got a reel of 3/16" brake pipe here, so I'll cut off some and give it a try to see how it fits for future reference. I presume "swage" refers to a tool for expanding pipes or the process involved.

In any case, my pipe has arrived from Citroen --- they got it delivered overnight from their Midlands central depot. The new pipe is quite short, so wherever it disappears to in the middle can't be very far.

Thanks for your help Alan.

David
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Post by AlanS » Sat Jun 10, 2006 11:27 pm

FWIW, "swage" is basically stretching the pipe so it fits over another pipe which was of equal size.
With copper, a "swaging tool" is in fact a flaring tool with a slight difference in that where a flare punch has a 60 or 45 degree tapered end, the swaging tool will start at a size below that of the pipe it's being used on and steps up in gradients to a couple of sizes above that required for a neat swage.
With copper, the pressure of screwing down the punch onto the pipe held in the flare block will stretch the tubing enough for it to become a neat fit. With steel, the pipe is usually held in the block which in turn is held in a vice. The pipe is heated and a swaging "punch" is used which is like the end of the one described but instead of screwing down, it is tapped in with a hammer until it stretches the pre heated steel pipe to the desired diameter.

The swaging punches for this flaring/swaging set can be seen at the bottom LHS of this pic.
This is the type used for copper.

Image

I think you'll find it's easy to get to like I said above, but going to a bit of drama re: swaging as I reckon as these cars get older, there's more going to need this info.:wink:


Alan S
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ellevie
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Post by ellevie » Mon Jun 12, 2006 6:27 pm

I had a look at mating the Citroen 3.5mm pipe with 3/16" standard UK brake pipe. They don't even come close to fitting, but the good thing is that if the 3/16" can be used as a sleeve by heating it up, then it should make a really tight fit. I think I will buy a soldering torch and have a play around with it --- it will be useful to get some experience of this type of soldering.

Interestingly, I have some 3mm internal diameter polythene pneumatic tubing, and I had a go at cutting the brake pipe and using a few inches of this as a sleeve. It makes a pretty tight fit, but predictably when the brakes were applied, a piston action tended to push the pipe ends apart resulting in a slow leak. However, I managed to tie the two ends of the pipe together securely with multiple turns of string and this has "held" so far. I will leave it in for a few days to see what happens. It would be interesting to see if this trick would work with the suspension pipes.

I wonder if there is some way of temporarily fixing a small leak in a brake pipe or suspension pipe, without cutting the pipe in two, by using some kind of liquid metal or similar paste ? This would be really useful if it worked.
David

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jeremy
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Post by jeremy » Mon Jun 12, 2006 6:35 pm

Unless I'm much mistaken brakes have a rather more important and immediate safety function than a central heating system.