Repairing a steel brake pipe with kunifer?

Question

On daughters new to her 2010 Meriva checkover the local garage mentioned a couple of instances of brake pipe surface corrosion but only minor and that would likely only be 'advises' on the MOT in Feb.

Q. Given that from the ABS unit, all though the engine bay and all the way under the car and nearly up to the rear wheel looks like new, would it be a viable solution to cut the steel just before the rusty bit, flare and then continue in cupro nickel to the flexies? *Can* you flare the factory steel pipe with the std d-i-y type tools?

I replaced the n/s/f pipe from ABS to inner arch in cupro on my Meriva a while back and that wasn't too bad because it was only short and mostly in the engine bay but I understand steel is better from a anti crush-ability POV so might be a better solution under the car?

Obviously it would be 'better' in one continuous length but I believe I've previously worked on cars with in-line couplers here and there (probably to ease manufacturing).

Cheers, T i m

Roger Mills · Accepted Answer

If it's only surface rust, I'd be inclined to clean it up with wire wool and then smear some grease over it.

T i m · Answer

Where the pipe crosses over from the n/s/r (after running down the length of the car) to the o/s/r brake, it looks like there is a 30mm long section that was held in a clip that now has some rust on it.I think the bits on the front are where it curls under the front wheel inner arch and onto the bracket to the flexy.I assume if I was to go wire wool > grease the "Brake pipes corroded, covered in grease or other material" are just an advisory and wouldn't constitute a fail.Cheers, T i m

Roger Mills · Answer

I'm not sure that it's even an advisory if you have removed the obvious signs of rust and if there's no visible pitting.

Fredxx · Answer

1.1.11. Rigid brake pipesIf the metal brake pipes have surface dirt that needs to be removed before it’s possible to assess their condition, you can lightly scrape the pipe with a specialist brake pipe corrosion tool or the corrosion assessment tool ‘spade end’. It must be done with care so that any protective coating does not get damaged.Chafing, corrosion or damage to a rigid brake pipe so that its wall thickness is reduced by 1/3 (approximately 0.25mm for typical hydraulic brake pipe) justifies rejection, although it’s accepted that this is not easy to determine. If you are not sure whether the pipe is sufficiently deteriorated to justify rejection, you should give the benefit of the doubt.____________________________________________________Tricky one, minor pitting is ok.

T i m · Answer

If we assume it is sufficiently badly pitted that someone looking to be 'better safe than sorry', what about the idea of chopping off the pipe just before the rusty part (in the case of the o/s/r in this case) and replacing from there to the brake area in Kunifer type stuff (on the grounds it's easier to form than steel)?

The idea is that ... if it's 'perfectly feasible' to apply an appropriate flare using the std flaring tools used for the copper based pipes, could leaving the 'stronger' steel pipe in place though the majority of the car but having a joint, be better than replacing it from end to end?

Given it's something quite important, my 'do it right, do it once' ethic says replace it end to end but that might mean that you end up with a more crushable pipe being exposed over a greater length?

I'm guessing you can't buy OEM brake pipes pre-formed for something that old (or anything)?

Cheers, T i m

Repairing a steel brake pipe with kunifer?

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