The great thing I learned from this thread is that it's the copper ions (from typically copper brake lines) that causes the pitting in the iron components. Not water!
I bow to information presented. However, water vapor does play a role, albeit not the only role, in brake component deterioration.
Brake fluid in an open container will absorb moisture. In a closed system, it shouldn't absorb water. Since most systems get opened and fluid added as the pads and/ or shoes wear, when they are replaced. many mechanics just force the pistons in without removing the extra fluid. this causes the seal on the master cylinder to be damaged as the excess fluid finds somewhere to go. The result: water vapor can enter the system.
Most cars and trucks use Steel brake lines as Copper lines can't take as much pressure Steel can handle more heat than copper lines too.
...not so fast Jim...
Current double-wrapped, brazed and coated steel tubing is susceptible to brazing voids, coating voids, poor coating adhesion and discontinuities. These susceptibilities, combined with random service damage, mean the actual service life of the brake tube materials presently used in U.S.-manufactured vehicles should be considered unacceptable.
...trailer test results demonstrate that 90-10 coppernickel tube is a significantly better choice for automotive brake lines than low-carbon steel .
For many years the tubing in automotive brake systems has been manufactured from low-carbon steel. One or more superficial coatings are applied after brazing to protect the steel substrate from corrosion, because steel has no inherent corrosion resistance to the road environment. Although coating composition has changed since the original hot-dip lead-tin coatings were used, coating flaws remain a problem. The addition of zinc-rich paints did little to improve the protection of the tube. Current aluminum-zinc coatings and added polyvinylfloride coatings are still inadequate to totally protect the steel tube.
...not so fast Jim...
Current double-wrapped, brazed and coated steel tubing is susceptible to brazing voids, coating voids, poor coating adhesion and discontinuities. These susceptibilities, combined with random service damage, mean the actual service life of the brake tube materials presently used in U.S.-manufactured vehicles should be considered unacceptable.
...trailer test results demonstrate that 90-10 coppernickel tube is a significantly better choice for automotive brake lines than low-carbon steel .
For many years the tubing in automotive brake systems has been manufactured from low-carbon steel. One or more superficial coatings are applied after brazing to protect the steel substrate from corrosion, because steel has no inherent corrosion resistance to the road environment. Although coating composition has changed since the original hot-dip lead-tin coatings were used, coating flaws remain a problem. The addition of zinc-rich paints did little to improve the protection of the tube. Current aluminum-zinc coatings and added polyvinylfloride coatings are still inadequate to totally protect the steel tube.
I would be nice if more of the copper nickel tube was on the road. Most of the cars coming into your view are running the mild steel stuff. and rotting from inside and out.
Most of the color change is from seal residue. The C clamp in my tool box that spread pads in years gone by has a new use. Times change and having that junk in the system does no good at all.
The junk as I see it being the water raising the boiling point leading to fade and corrosion and the particulate debris that clogs the various components. whatever is in suspension in this brew getting rid of it is good and the right thing to do. I do it my my own.
karl
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