There is no one perfect brake fluid. There are advantages and disadvantages to
each. You've brought up a few points, but somewhat muddled them.
Silicone brake fluid is not hydroscopic. It does not absorb water, quite the
opposite. Standard DOT 3 or 4 fluids do this, they are the hydroscopic fluids.
This can be good or bad, depending on the situation. A brake fluid that absorbs
water will disperse it throughout the fluid. This reduces the amount of water
in
critical heat areas like the caliper. Water expands dramatically when heated,
and in a caliper this is certainly not a good thing. Silicone fluid, by not
absorbing the fluid, and being lighter then water, tends to puddle any water
that
does get in the system, with the caliper being the lowest point, and the natural
place for entrained water to travel to. Not good when braking hard. Puddling
also tends to exacerbate rust in the area of the water puddle. In any case,
brakes should be flushed regularly, eliminating water from any brake fluid.
Silicone tends towards a spongy pedal for several reasons:
1, It is quite compressible. I know the old drill about fluids being
incompressible. That drill is wrong, especially with regards to silicone
fluids,
they are quite compressible.
2, Silicone fluids become progressively more compressible as they heat up. DOT
3, 4, and 5.1 do not, until they boil. So silicone fluids will become steadily
spongier as you work them hotter by braking. It's an inherent property of
silicone brake fluids.
3, Silicone fluids tend to entrap air bubbles. The viscosity of the fluid does
not allow minute bubbles to dissipate. This is why many times silicone fluids
look opaque. You can help this greatly by heating the fluid prior to
installation, promoting the dissipation of the air bubbles already in the fluid.
And, by not causing more air to be frothed in when you work with the fluid.
But,
air entrapment is another inherent property of silicone brake fluid.
Make no mistake about things like DOT3 and DOT4 fluids being the same. They are
not. Not even within their own categories. That would be the same as thinking
that all 10w-30 oils are identical. Many racers run Ford Truck Heavy Duty DOT3
fluid. It is excellent. Castrol LMA is also quite good. The new DOT5.1 (more
logically, it should have been DOT6, since it is not a silicone fluid) is even
better.
As for paint resisting DOT3 or DOT4 fluid, certainly there are many paints that
shrug it off without a problem. Japanese cars have been painted with this type
of paint for decades now. My truck has had brake fluid leaking on its inner
fender for about 16 years now, with no paint damage. Similar my Hondas. When
selecting a paint, simply specify that you want it to be resistant to brake
fluid.
And the gauntlet question, I'd suggest going over to the racers board of your
choice and posing that question. You will find serious drivers there who have
tried it, and gone back because it sucks for hard driving.
/// spitfires@autox.team.net mailing list
/// To unsubscribe send a plain text message to majordomo@autox.team.net
/// with nothing in it but
///
/// unsubscribe spitfires
///
|