what size solid brake line

[dullbird]

Hi Guys

does anyone know what size brake line is used for the series vehicles and a rough idea of how much would be needed?

are there different wall thicknesses?

[d@rk51d3]

Hi Guys

does anyone know what size brake line is used for the series vehicles and a rough idea of how much would be needed?

are there different wall thicknesses?


3/16
comes in rolls about 20ft long, from memory.

[dullbird]

excellent thank you:)

[dullbird]

so next question

what material

now last time I suggested copper everyone was saying you shouldn't use copper for the brake lines however it specifys in the book that the lines are made from copper.

so

Copper
steel
Stainless steel
galvanised steel
any others?

what should I get a roll of this is the next stage for our car making up the brake lines

[JDNSW]

The originals are galvanised steel. My understanding is that it is no longer legal to use copper for brake lines (this is because copper will work harden and crack) although I'll bet it is still being used, and provided the line is supported properly I doubt it is a serious problem. I think there is a special corrosion resistant alloy you can get (at least in those parts of the world where salt is used on roads). Have a talk to a brake place.

John

[dullbird]

copper is still used in the UK I think.....

I have seen aluminum as well while doing a search online.

[Lotz-A-Landies]

DM

The tube is 3/16", it is still legal to use copper brake lines, but it has to be special thick wall tube branded for brake lines. It is not legal to use thin wall or industrial copper tube, unless it has the branding for automotive brake applcations.

Diana

[JDNSW]

I think you will find that the brake line branded copper is not pure copper but is a special non-work hardening alloy, even if described as copper.

John

[chazza]

I think the work-hardening "issue" is a bit of a Furphy, given that steel and aluminium brake tube can also work-harden. There appears to have been problems in some jurisdictions where people in their ignorance have used the wrong thickness copper tube with disastrous results, leading to all sorts of untruths being told to myself by motor parts factors that; "copper pipe is illegal"; "no longer made" , etc. The best thing to do, is to ring your licencing authority engineering section and ask them for the truth and their advice.

Dullbird, if you are re-doing the whole car, buy two rolls of tube for good luck. If you use steel, ask for bundy tube. As Diana says it is most important to tell the shop what it is for i.e. brakes. If you use steel you will need to buy a rather expensive double-flaring kit; if you use copper, a cheap single flarer and the ability to heat copper to a dull-red heat so as to anneal it, will be needed,

Cheers Charlie

[dullbird]

Hi Chazza we already have a double flaring kit :)

[JDNSW]

I think the work-hardening "issue" is a bit of a Furphy, given that steel and aluminium brake tube can also work-harden. .........
Cheers Charlie

I think that it is a bit of a furphy in that work hardening is very rarely a problem - I have seen copper brake lines used many times over the years, and have never seen this as a problem. On the other hand, I have seen copper fuel lines work harden and crack on quite a few occasions - perhaps because they are larger diameter than brake lines. But copper is certainly a lot more easily work hardened than most grades of steel, particularly those used for tubing of any kind, and also work hardens much more readily than most aluminium alloys, although I have had no experience with aluminium brake pipes.

John

[dullbird]

what do you guys mean when referring to work hardening? a hardening of the metal causing fatigue/cracks perhaps?

[d@rk51d3]

A bit like when you bend a piece of wire back and forth. It's flexible at first, but soon hardens, becomes brittle and snaps.


...... Something like that (I think).

[JDNSW]

what do you guys mean when referring to work hardening? a hardening of the metal causing fatigue/cracks perhaps?

Some, perhaps most, metals, when subjected to repeated deformation have the structure of the crystals that make up the metal modified in a way that makes them harder and at the same time more brittle. The increased hardness is rarely a problem (but see the comment below) but the increased brittleness is, as it can bring the amount of deformation into the range that results in fatigue cracking with relatively few cycles, even though this is not a problem with the original properties of the metal.

There are two metals in common use where work hardening is very pronounced. The first of these is copper. This was first discovered in prehistory where copper was the first metal used, and it was found that repeated hammering hardened the cutting edge of tools and weapons. Apart from brake lines, it is also a problem with electrical wiring and is the reason that all wiring in vehicles is made with very fine individual strands - it is not just so they can be bent during installation.

The second metal is most grades of stainless steel. For this reason, the use of stainless steel must be avoided in ant place where it is subject to vibration and carrying a heavy load. If it is absolutely necessary to use stainless, then it is necessary to use a design that minimises the cyclic deformation, so that it is bad practice to replace carbon steel bolts with stainless, especially in critical or high load positions. A further effect is to make stainless steel difficult to machine, as the work hardening makes the surface harder than most cutting tools unless every cut is deeper than the depth of hardening created by the previous cut.

John