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.
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