rogtwo@aol.com

   

OK, here I go causing trouble again. Well, I don't mean to cause trouble,
but that's what often seems to happen -- sorry.

First the disclaimer -- I'm no expert on brake fluid, so what I say below is
mostly speculation based on the little I know about grease.

In the aircraft industry, there is some disagreement about whether it's
better to have hygroscopic grease (ones that ABSORB water) or hydrophobic
grease (ones that REPEL water). The argument boils down to this: If the
grease is hydrophobic, then any water that gets in will sit in little drops
and possible cause significant corrosion right where the drops sit. If the
grease can absorb the water (is hygroscopic), then any water that gets in is
absorbed and distributed throughout the grease, thus eliminating the drops of
water that can cause excessive corrosion. Of course, the grease is now damp,
and may cause corrosion over a larger area. This is why there is
disagreement about which is better -- drops of water in limited locations, or
having the water diluted in the grease. Obviously hygroscopic grease should
only be used in a well sealed environment where it won't be absorbing water
out of the air.

So, now to brake fluid. Since the brake system is well sealed, hygroscopic
brake fluid (e.g., DOT 3), MAY be advantageous. That is, if a tinny bit of
water gets past the wheel cylinder seals when you are swimming, this water
will be absorbed into the fluid. This MAY be less corrosive to your wheel
cylinders than having the water sit as a drop in the bottom of the wheel
cylinder as would happen with a hydrophobic brake fluid (DOT 5).

I really don't know which is better, but in either case it's a good idea to
bleed all the 4 wheels regularly (like yearly). Personally, I'm not going to
bother to switch to DOT 5.

Roger St. John
White '63
Seattle

PS - There is no need to start with clean fluid in your bleeder jar. There
is no way that you are going to suck fluid all the way up your bleeder hose
from the bleeder jar. That is, all the fluid (if any) that gets sucked back
in through the bleeder screw is going to be the dirty fluid (that just came
out of the wheel cylinder) that is still in your bleeder hose. The clean
fluid in the jar isn't going to get near the wheel cylinder.


[Non-text portions of this message have been removed]

Bill Connelly

   

Seeing as how brakes are such a critically important matter and all, I thought
some folks might be interested in a reprise of something I originally posted to
this List in February 2001 when the subject of DOT 3 vs. DOT 5 brake fluids last
came up. The second link below might be of particular interest since it's a
word-for-word transcription of two items on the matter from a well-respected
source, _Auto Restorer_ magazine.
~Bilgey~
=================

> I have a question for the group, I,m getting ready to rebuild the
> complete brake system. I am going to use silicone brake fluid in the
> system. I would like to know everyone's feelings about silicone
> fluid.

Search the List Archives on the topic "brake fluid" at:

http://www.escribe.com/automotive/amphicar/search.html?query=brake+fluid


There's lots there from an earlier discussion on the subject of DOT3 vs.
DOT5, including a transcript of an article from _Auto Restorer_ (October
1999 [ v 11, n 10]. p. 6 and 23-25) at
http://www.escribe.com/automotive/amphicar/m1656.html


~Bilgemaster


[Non-text portions of this message have been removed]

Larry & Nancy Solheim

   

I can't comment on the technical differences, but
after 9 or 10 years, the silicone (DOT 5) fluid has
been great in our application.

When initially preping Amphi ('66) we found the RR
horizonal line to be rusted through (the wet sprinkle
on my neck when bleeding the brakes was a nasty
surprise). I removed all of the cylinders and lines &
cleaned w/ alcohol. We did the same when rebuilding
MetalBeast ('64) later. We also turned the pistons to
remove the extensions, so standard Wagner or Raybestos
kits fit, at about $6.00/ cylinder. Because of that I
have been removing, honing, and replacing the rubber
components every three years. From experience I know
now that it actually hasn't been necessary, but
because of our heavy road/water use as we travel the
country, it seemed to be a good idea.

BTW, beacuse Hugh was out-of-stock on standard linings
when needed, I had semi-metallic (black) linings
bonded to Amphi's shoes in 1999. They require some
double-footing to dry after swimming (although no more
than the original linings) and show no no adverse wear
after four years. Because there are no rivets I would
think I would have more life to the brakes. too.

--LarryS

--- Bill Connelly <billiam@erols.com> wrote:
> Seeing as how brakes are such a critically important
> matter and all, I thought some folks might be
> interested in a reprise of something I originally
> posted to this List in February 2001 when the
> subject of DOT 3 vs. DOT 5 brake fluids last came
> up. The second link below might be of particular
> interest since it's a word-for-word transcription of
> two items on the matter from a well-respected
> source, _Auto Restorer_ magazine.
> ~Bilgey~
> =================
>
> > I have a question for the group, I,m getting ready
> to rebuild the
> > complete brake system. I am going to use silicone
> brake fluid in the
> > system. I would like to know everyone's feelings
> about silicone
> > fluid.
>
> Search the List Archives on the topic "brake fluid"
> at:
>
>
http://www.escribe.com/automotive/amphicar/search.html?query=brake+fluid
>
>
> There's lots there from an earlier discussion on the
> subject of DOT3 vs.
> DOT5, including a transcript of an article from
> _Auto Restorer_ (October
> 1999 [ v 11, n 10]. p. 6 and 23-25) at
>
http://www.escribe.com/automotive/amphicar/m1656.html
>
>
> ~Bilgemaster
>
>
> [Non-text portions of this message have been
> removed]
>
>


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