All American cars manufactured in the last 70 0r 80 years and most Foreign
cars manufactured since the end of WWII have used a doublewall furnace
brazed steel tubing which was zinc,tin or terne coated for all of the hard
lines. This tubing is usually called Bundy tubing after the name of the
original patent holder. It is far more likely to rust from the outside in
than the inside out. I am familiar with this product because I manufactured
it,under license, for 20 years in South America. Regards, John Harden
----- Original Message -----
From: "Mark Palmer" <mgvrmark@hotmail.com>
To: <vintage-race@autox.team.net>
Sent: Monday, January 15, 2001 1:48 PM
Subject: Brake Line wrap-up
> Listers,
>
> Thanks to all who responded to my request for advice on brake lines.
Since
> some of them responded to me privately, I thought I'd pass along a summary
> to the vintage race list for those of you who may be interested. All
> others, hit the delete key now.
>
> Interesting that about half the respondents had flex lines throughout the
> car (no hard lines), and about half had hard lines with flex at suspension
> points only. The "hard liners" nearly all said that if you use flex lines
> throughout, the pedal will be mushy ... HOWEVER, every single respondent
who
> had 100% flex lines reported that they have a very firm pedal! So I
> conclude that the "hard liners" concern is probably misplaced, possibly
> because they haven't tried 100% flex lines recently. I'd conclude that
> either method works fine.
>
> The only real disadvantage with 100% flex lines, seems to be cost. It is
> more expensive per foot. It may be a little heavier, but that seems
> insignificant to me. Some people feel that it looks out of place in a
> vintage car, particularly a vintage production car. It is, of course,
> easier to route through the car -- but must be supported very well. Some
> folks feel that flex lines have a life of no more than ten years, and
you'd
> have to replace it about that often, which again is costly.
>
> For hard lines, the most knowledgeable respondents recommended steel.
Hard
> lines may last virtually "the life of the car", (not sure what that means
in
> vintage?) but plain carbon steel could suffer internal corrosion over
time,
> since most brake fluid is hygroscopic. The tubing is apparently available
> galvanized, which would address the corrosion concern. Stainless was
> generally felt to be overkill, and may be hard to bend smoothly. The
copper
> alloys (NOT generic soft copper, as used in fuel lines) were felt to be
> perfectly suitable for the job, HOWEVER that may trigger questions &
> skepticism by some Tech Inspectors who are not familiar with the various
> grades of copper alloy. So, simply in order to avoid a perceived issue at
> Tech, I wouldn't recommend copper.
>
> There were several people who recommended specific types of fittings,
> flares, etc and I haven't sorted through that yet.
>
> A few people brought up VERY good points about brake line routing
> (regardless of whether it's hard or flex): avoid routings that could
expose
> the lines to damage by jacks, by engine removal/installation, by track
> debris or an off-course excursion, or by accidents in general. Also,
avoid
> the area around the flywheel/clutch (or shield the line), so that if the
> flywheel grenades the shrapnel won't slice a brake line. Also, obviously
> avoid high-heat areas like exhaust pipes.
>
> Sizes: general agreement seems to be -3 flex for brakes, or 3/16 hard
> tubing. For clutch, -4 flex and 1/4 hard (clutch line typically has more
> displacement -- i.e. more flow -- than brakes, and much lower pressure).
>
> Thanks for everyone's input, I learned a lot & remain impressed by the
> combined knowledge of this list's inhabitants!
>
> Regards,
> Mark Palmer
> _________________________________________________________________
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