At 02:52 AM 5/31/2002 -0400, you wrote:
>I
>have never had a copper pipe rupture and I have had plenty. Is this risk
>particular to heavy U.S. cars? If so I will ensure that the replacement pipes
>are steel.
>
>Tony V.
Tony, I am not sure if Imperials have particularly higher brake line
pressures than your usual car in Britain. I think that the higher brake
forces are achieved by using larger calipers, brake cylinders, and master
cylinders rather than higher pressure. Also, drum equipped cars like yours
have inherently lower line pressures. I would guess the shop manual will
help with the question of how high pressure is built up inside the brake
system. If I recall, on a 68 (disk brakes) the pressure can reach 1200
psi. Now, does copper have sufficient strength? Well, some of these pipes
(flexible hoses) are actually rubber, so if rubber can take the pressure,
then copper should too. Of course, the rubber hoses are of much higher
thickness than the steel lines to limit expansion. Then again, we do not
know how thick wall the copper lines used in the UK are. They might be of
thicker wall than the steel lines used in the US.
Calculating the stresses in a pipe based on pressure, pipe ID and wall
thickness is not difficult. If you can provide me this information, and
the copper alloy used (I can hopefully find info on the strength of the
material) I may be able to do some rough calculations and tell you if the
material selection is improper. My guess though is that if they use it in
a large scale over there, it should be fine. Here in the US, often the
"safety" regulations go beyond sense...
D^2
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