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Just had my astra 1.4 95 mot, it passed! first time, the garage guy said you want the good news or bad,before my joyous mood expires, he gave me some advice on some of the car niggles, the metal pipes on the brake is rusted up, the handbrake needs adjusting, god knows how to adjust it,one of the rubber bush needs replacing, and thats it also it needs a lick of underseal, my question why the hell vauxhall make metal pipes for the brakes, why not plastic or rubber..
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sajid
Metal mesh reinforced, flexible, plastic pipes are used for connections that require movement, for example where the brake pipes feed the wheels. The pressures in a brake system are very high (several hundred pounds a square inch), and so these metal reinforced plastic pipes are unsuitable for use all through because although they hold the pressure, they expand too much. It would be impossible to use unreinforced plastic pipes. The actual quantity of fluid moved during braking is very small, and too much of this flexible pipe in the system would cause problems with pedal travel.
So, Vauxhall, like all other makers, use small bore rigid pipes for the majority of the system, as these expand very little under pressure. These are usually, these days, made of zinc coated steel in a plastic coat for corrosion resistance. Inevitably, stone damage may pierce the coating, and rust can start. Aftermarket copper alloy pipes are available, and are very popular for classic cars. I believe they were used by Volvo a while back. I don't know if that's still the case.
Regards
john S
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Sajid
John is right, copper pipes repace steel ones, because they are easier to fit as replacements, and have better anti corrosive properties, whereas zinc coated steel is much cheaper than copper and it is much easier to fit preformed steel pipes on the production line than it is as a repair afterwards.
I replaced all my pipes on a Renault 11GTL I had about 11 years ago. Preforming long copper pipes prior to fitting them doesn't work, especially if you're working in a confined space. There are so many physical obstacles to overcome when feeding the pipes through that all your hard work in this respect will be wasted.
The method I adopted was as follows using a reel or two of copper break pipe available from motor factors, a handful of connectors and some string. Oh and you'll need a break pipe flaring kit. About £10 to £20 I think (I borrowed one).
1)Bleed the system (or at least that part affected by the pipe(s))
2)Remove the pipe to be replaced (one at a time)
3)Using the string, measure the length of the old pipe and mark/cut string
4)Measure length of copper pipe using marked or cut string, leave an extra 0.5" for flaring.
5)Insert connectors at both end BEFORE FLARING (no good afterwards)
6)Flare both ends
7)Offer one end up to connection on car, connect loosly, then form the rest of the pipe to the approx profile of the old one as you go.
8)You should end up with the other end meeting the appropriate connector with little adjustment/forming. connect and tighten
9)Tighten first connector and double check both connectors.
10)Make sure that the brake pipe is properly clipped in as the old one was and check for sharp corners/edges that could chafe it.
11)If you're to replace more pipes, start at (2) again, othewise continue to (12).
12)When you're satisfied it has been well fitted - refill and bleed system.
13)CHECK FOR LEAKS and remidy as necessary.
H
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All Vauxhalls have had plastic coated brake pipes since before '90, which shouldn't corrode. Our '90 Nova has failed several Mot's for several things but never corroded brake pipes. Have the pipes checked independently to recheck whether you're being conned.
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Sajid
Any update on this?
Roger,
I don't think he's being conned as such because the car did pass the MOT.
H
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Copper pipes are a good replacement, easy to form and easy to flare. Trouble is, they tend to 'stick' in the steel nut attaching them to the component. Removal often results in a twisted pipe.
The last time I bought a roll of steel pipe, the 'new' copper stuff was cheaper and easier to work with.
Why then, don't manufacturers use it from new?
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Because, for the volume that they need, steel is cheaper.
Steel currently weighs in at a scrap yard for about £15 per tonne (1.5 pence a kilo)
Copper currently weighs in at not far off 100 times that.
Lead is around half that of copper.
Stainless steel is either 5 or 10 pence per kilo
Aluminium is a lot more than that -50p a kilo?
I only know this because I have cashed in plenty of scrap removed from properties in the course of renovation. I guess the exact prices depend on market forces and where you are in the country.
I'm surprised that the steel pipe was more expensive. I can only assume it was priced like that due to some perceived advantage that the manufacturer thought it presented. Also it may have been stainless.
If you're concerned about use of steel nuts twisting, use brass nuts.
H
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Hugo, my astra had the brake pipes from the rear replaced when i bought it secondhand, although my astra has passed the mot, with no work at all being undertaken, i was given advice on what the car may need doing in the near future, the garage recommended a lick of underseal to stop it rusting, and i am not sure what the rubber bush is but it was the near side one that is going soon in the near future,any idea of the cost of the rubber bush is it a complicated job??
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There are loads of rubber bushes on these cars, however, chances are it is not a complicated job. These are on the anti - roll bar and the front wishbones that form part of your front suspension. Ask him where this bush is.
Suggest you do the underseal first, as you can do that yourself.
H
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does anybody know the diameter of the copper pipes needed?
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does anybody know the diameter of the copper pipes needed?
For brake pipes you need 3/16"
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