flexi brake hoses

[voucht]

Hi Paul,

That is a legitimate question

Actually, technically, when it comes to overall brake pressure, for us, there is no real upside of using full SS (stainless steel braided Teflon hose) lines instead of copper pipes on the non-flexible lines of the brake circuit.

However, on the paper, SS braided hose has a higher service pressure than copper pipe (that is the reason why it is preferred in racing cars for the whole braking circuit, as very high braking pressure can be reached):
- service pressure of 3/16'' copper pipe is 250 bars
- service pressure of dash-3 SS braided Teflon hose is 320 bars.

But I doubt these kind of braking pressures are reached in our cars, so this is not a valid argument when it comes to our Roadsters. Therefore, we can consider that there is no difference in that matter between the 2 kinds of hose, and also that there will be no deformation under pressure on both of them (which is different when it comes to flexi only: SS braided ones will always be better and offer better braking consistency than OEM "rubber" ones, because they don't swell, or get dilated, under heavy pressures, as OEM flexi might do).

But there are other things to consider, and there, SS brake lines have some upsides that might be worth considering:
- durability. They won't rust. I personally saw damages of the corrosion on copper fuel pipes in my Renault Rodeo (which is basically a Renault 4), and it is blood scary! But I'm sure you've seen worth in your career
- stainless steel braid provides protection against both wear (friction) and shocks (such as projections of stones)
- no tools required to bend the pipe. Easy to assemble as it is flexible.
- no tools required to make the seats on the pipe: proper fittings are crimped on the flexi lines.
- fittings of the brake lines the company I used to work for supplies are in stainless steel, and not in plated steel, so they are also more durable than the cheap fittings usually used with copper pipes.
- very neat finish on the car: SS lines looks very technical and professional.

The downsides, if you compare to copper pipes are:
- of course, the price. But it is less a hassle to install also,
- you can't achieve very tight curve radius with the SS braided hose (not as tight as with copper pipes): 38mm mini for dash-3 SS braided Teflon hose, 10mm for 3/16'' copper pipe,
- with copper pipes, you “fabricate” the lines directly on the car, while installing them. With a full SS line circuit, you need to plan for each line which will compose the circuit before ordering (length and both fittings). It is not hard to do, and I provide help for that (schematics, etc.), but it has to be considered.

So, I think it is like most of the other elements of the car: it is just a question of choice, what to favour between technicality, practicality, durability, cost, look, etc. but it is good to know the perks and the downsides, so thank you for your question, and I hope I answered it

[Richard Dryden]

Hello Sylvain, thank you very much for all the information will have to work out what I need exactly. I will get back to you as soon as I do some measuring etc.I almost just private messaged you but I thought it may be a useful question for other builders too.

Cheers Richard

[flyerncle]

Valid contribution (not argument ) for and against for both,it just gave me food for thought and other peoples thoughts on the why and wherefore for both.

Just checked my pipe stock and they quote theoretical burst of 965 bar and working pressure of 214 bar so safe enough for our use and that is 3/16 pipe.

Merci Mon ami.

[loony]

So - what rear fitting setup is optimal for Sierra rear disk brakes with "angled" (or Talon) uprights ?
I thought about straight fittings, but maybe angled 45deg. or 90deg. fittings will suit better ?

My build is not at this stage at the moment

[voucht]

Hi Lucas,
I would say it depends where are the brake line brackets located on your chassis. This will have direct influence on the angle the brake line arrive on your rear calliper with. The angle should be as natural as possible.
Straight fitting are very nice because they are very compact. Angled fittings, (45° and 90°) are not as compact because of the angled tube, so better chose them only if you can not fit a straight fitting.
We use a 45° fitting on drum brakes with "book" upright, because they allow to fit the brake line directly into the drum cylinder without using the piece of copper pipe as explained in the book.
Personally as I have "Talon" uprights (angled RU8) like yours, and drums, I have a straight fitting in the wheel cylinder.
For rear disk brakes with "Talon" uprights, I think a straight fitting should be OK. But of course, as I said above, it depends where your brake line comes from: the important thing is to have a natural angle between the hose and the fitting once the brake line fitted.
Hope this will help