I just read last week that DOT 5 has a higher boiling point than DOT 3 &
4. I read this in a suspension tuning book, that I would consider quite
reliable.
James Nazarian
'71 B roadster
'71 BGT rust free and burnt orange
'74 BGT going by-by soon
'63 Buick 215
On Thu, 24 Feb 2000, James H. Nazarian, Ph.D. wrote:
> Hi Max,
>
> As I have understood, DOT 5 does have a lower boiling point than the other
>brake
> fluids. The difference is not great, and falls into the vicinity (I think) in
> excess of 400 F. Most amateur LBC racers, in their wildest dreams, will never
>see
> brake fluid temperatures like that. So be it if Silicone isn't the best for
>race
> cars, but it is great for street cars. IMHO it is silly to be changing brake
>fluid
> once, twice or more times per year when there is a better solution available.
>I
> hate to think where all that DOT 3 & 4 brew gets dumped every year. Silicone
>is
> inert, non-irritating, non-toxic and, for the most part, non-allergenic. As
>for the
> breast implant controversy, I prefer Coke: "It's the real thing."
>
> Jim
>
> Max Heim wrote:
>
> > Actually, I seem to recall that the knock on silicone is that it had a
> > lower boiling point, and that with hard driving and disk brakes, it could
> > potentially boil. Steam is highly compressible. For this reason it used
> > to be strongly recommended for show cars (safe for paint) and
> > contraindicated for race cars (obviously), with everyone in between free
> > to choose. Haven't heard this lately, perhaps newer formulations have
> > fixed this.
> >
> > James H. Nazarian, Ph.D. had this to say:
> >
> > >Gents,
> > >
> > >> The three problems with silicone are that,
> > >> 1. it does not absorb water. This allows water to pool in the lines
>unless
> > >> you bleed it out every year.
> > >
> > >Hydrophobia is not a detraction of DOT 5, but a benefit. Can someone site
>an
> > >example of definitive research showing that water will pool in silicone? I
> > >don't
> > >think so! Try leaving some in an open graduated cylinder for a year or two
> > >and
> > >see if the volume changes, or any pools of water show up.
> > >
> > >> 2. it is (or was in original formulation) just a bit more compressible
>than
> > >> DOT 3 or 4 brake fluid. This may only be in early silicone fluids and
>could
> > >> be much better now. Barney, you use that A for some serious
>autocrossing.
> > >Did
> > >> you notice any difference in pedal feel between DOT 5 and DOT 4?
> > >
> > >Compressibility? Of a liquid? If such a thing could occur, I seriously
> > >doubt one
> > >could detect it with a foot.
> > >
> > >> And 3. the above seal swelling problem.
> > >
> > >I respectfully suggest this is a myth. If the stuff is no good I'd
>appreciate
> > >some proof before I remove what appears to be perfectly performing, 10
> > >year old,
> > >anhydrous brake/clutch fluid, and replace it with rust-worm food.
> > >
> > >Jim
> > >
> > >
> > >
> >
> > --
> >
> > Max Heim
> > '66 MGB GHN3L76149
> > If you're near Mountain View, CA,
> > it's the red one with the silver bootlid.
>
|