Text 258, 93 rader
Skriven 2009-07-10 10:53:46 av Roy Witt (1:387/22)
     Kommentar till en text av Robert Bashe (2:2448/44)
Ärende: Master Cylinders
========================
10 Jul 09 07:25, Robert Bashe wrote to Dan Ceppa:

 RB> Dan Ceppa wrote to Robert Bashe on Thursday July 09 2009 at 09:59:

 RB> [Brake fluid]

 RB>>> It is clear, and your statement surprises me. I thought all the
 RB>>> stationary lines were made of stainless steel and the flexible ones
 RB>>> of synthetic rubber. How would such a system get contaminated with
 RB>>> iron oxide? I can't imagine brake lines being made of plain iron
 RB>>> tubing if...

 RB> "... only because the tubing could rust through or be thinned by
 RB> corrosion from the outside."

Sheesh! Nobody cut it off, you just didn't complete what you meant to
say.

 RB> You have a nasty habit of cutting off the important part of a
 RB> sentence in your quoting.

In spite of his many bad habits, he is innocent of that.

 DC>> There are still cast iron calipers and wheel cylinders out there.

 RB> The calipers don't contact the brake fluid,

Oh? By 'caliper' do you mean the linings? The caliper is the unit that
houses the brake fluid that powers the piston within the casting (I think
they're forgings, but that's beside the point). The flexible brake hose
you mention connects to the caliper and brake fluid does flow into the
caliper. The caliper is iron, some are made of stainless steel, but those
are usually aftermarket calipers. The Corvette has stainless calipers from
the factory.

 RB> and the cylinders are continuously in contact with the pistons,

Not exactly. The piston is fitted with neoprene o'rings that contact the
cylinder walls to seal the piston so that brake fluid doesn't leak from
it.

 RB> making it hard to develop corrosion - particularly in the absence of
 RB> air.

Heating and cooling of brake components, especially calipers, creates
condensation, which in turn creates iron oxides in the brake fluid. If
your brake fluid is brown, you have rust in it.

 DC>> Not all tubing is stainless.

 RB> Presumably anything exposed to the outdoors is, but of course even
 RB> iron doesn't corrode merely because of the presence of water. You
 RB> also need oxygen in some form.

Brake fluid attracts moisture, and this moisture can rust the insides of
the brake system. This moisture wasn't that big of deal 10 years ago, but
on ABS brake systems of today, the rust and other debris that accumulates
in the fluid can do lots of internal damage, and can be very costly to
repair.

Brake fluid can also break down over time from excess heat that is created
from within the brake system.


 DC>> And, even stainless will rust.

 RB> Since when?

Since it has been around. Even 300 series stainless steel contains enough
iron to attract a magnet. Anything that attracts a magnet will rust.

 RB> About the only way you can get stainless to corrode is
 RB> with chloride ion-containing chemicals such as calcium chloride, and
 RB> even then it's not surface corrosion, but point corrosion. You can
 RB> get holes in stainless, but surface rust? C'mon.

 DC>> Brake temperatures can approoach 1,000 deg F.

 RB> On the pads, and even then only when braking is hard and continuous.
 RB> Not in the hydraulic system.

LOL! That's why brakes fade...the heat generated in the pads and rotor
affects the rest of the system by convection, thus making the brake fluid
boil. Of course you won't get this from driving down the street, but you
will get it if you're having some fun on curvey roads.

                R\%/itt

Joy lives in the fight, in the attempt, in the suffering involved, not in
the victory itself.

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