Paul,
Agreed. Guy also mentioned (in our off-post discussion)the possibility
that one could "pre-condition" a seal for an adverse reaction to the
other.
Looking back, the only time I can remember converting from DOT 3 to
silicone was when I went to silicone fluid, in my daily-driver '72 Super
Beetle. However, I DID replace the master cylinder, at the same time.
Drove it another 100K (total mileage: 387,000), following the
conversion, with no ill effects. In fact, although it's been out of
service for the past 8 years, I frequently have to start it, and move it
around, to access various Spridget projects, and others. The brakes are
still fine.
However, after re-reading Adler's article, I have to agree that, when
converting from one fluid type to another, the smart thing to do is to
replace ALL seals/cups in the system, just in case.
BTW, on my Porsche 356B, when I rebuilt the brakes (new M/C, new hoses,
and rebuilt wheel cyls) I elected to stay with the DOT 4 ATE blue brake
fluid, and just renew it every two years (just like the factory
recommended, all those years ago). In addition to the '73 Midget I'm
working on, now, my '73 Beetle project (neck & neck with the Midget, for
completion date) will also get the DOT 4 fluid.
Since the cars are parked/stored in a very dry building, in a fairly
low-humidity climate area, I expect that the 24 month brake fluid
renewal will suffice.
Bud Osbourne
-----Original Message-----
From: Paul Asgeirsson [mailto:pasgeirsson@worldnet.att.net]
Sent: Monday, March 27, 2006 2:33 PM
To: Bud Osbourne; 'Guy R Day'
Cc: spridgets@autox.team.net
Subject: Re: Brake fluid question
Hi Bud,
It has nothing to do with contamination causing minor increase in seal
swelling compared to conventional brake fluid. It's simply the nature
of
Silicone that causes it. It doesn't really turn the rubber bits into
flower
pedals, just makes them swell a tiny bit more than the other does. And
because of that, sometimes a change in adjustment of the M/Cyl pedal is
needed.
Paul A
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