Max Heim wrote:
>
> Chris Kotting had this to say:
> >...
> >If you assume that DOT 5 and SBBF are the same (which they aren't but
> >this is the last time I will say that), I suppose if you hold your head
> >just right, this is theoretically true. But in the real world, if SBBF
> >doesn't absorb water (as the writer notes), and it's put into a clean
> >system (as the writer recommends), how is the water that's supposed to
> >be catastrophically "pooling" going to get in there in the first place?
> >Inquiring minds want to know.
>
> As for the water, it can (and does) condense out of the air in the master
> cylinder (which, you may have noticed, has a breather hole in the cap).
Yep. Several years ago I put this into both my completely *new* clutch
and brake systems on the '65 hoping to never have to replace the fluid
or these parts again, or at least not for several years. Two years
later the brake master went out, and sure enough, it was corroded from
condensation. (I live in the damp NW, and the MG lives outside.)
At that point I decided there was absolutely no reason to pay three
times as much for a fluid that has no benefit. Even worse, it wouldn't
dissolve and carry out all the condensed moisture even if you did flush
it with new every couple of years. At least glycol fluid will dissolve
the moisture and keep it from pooling so it can be flushed out. Makes
no sense to me to use this stuff unless you live in Phoenix maybe.
>
> >...
> >> DOT 5 is slightly compressible (giving a very slightly soft pedal),
>
> Hmmm, I don't think you are correct here. It's true that water doesn't
> compress. And hydraulic fluids are chosen from among the liquids that do
> not compress (hopefully!). But I don't think you can make a blanket
> statement to the effect that ALL liquids don't compress. But it's been a
> long time since chemistry class...
I got my BS in chem in '69, but back then all liquids were
incompressible. Things may have changed, I've long since lost touch
with this discipline>
>
> *I suspect the actual sequence of events was that, first, someone
> formulated a silicone-based brake fluid; and then, secondly, the DOT
> wrote up a spec based on the measured properties. If so, then there would
> not be any good reason to make a distinction...
I tend to agree here. Most govt safety and transportation standards are
developed "after the fact" and tend to follow industry recommendations.
See http://www.latimes.com/business/20000918/t000088124.html for a good
discussion of how NHTSA comes up with standards, or doesn't as the case
usually is.
>
> --
>
> Max Heim
> '66 MGB GHN3L76149
> If you're near Mountain View, CA,
> it's the red one with the silver bootlid.
--
Stuart MacMillan
Seattle
'84 Vanagon Westfalia w/2.1
'65 MGB (Driven since 1969)
'74 MGB GT (Restoring)
Assisting on Restoration:
'72 MGB GT (Daughter's)
'64 MGB (Son's)
Parts cars:
'68 & '73 MGB, '67 MGB GT
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