I have seen several people indicate that DOT5 is not good for racing or
autocross. Maybe I am naove, but I have had it in Tiny Tim (The
autocross Spit) ever since I built it in 2000. I have not seen any
adverse things that I would attribute to brake fluid. Maybe I should
change to Castrol LMA for a while and make a comparison. Naaaah! I'll
just leave well enough alone.
Joe
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On
Behalf Of Editorgary@aol.com
Sent: Wednesday, June 09, 2004 9:22 AM
To: fot@autox.team.net
Subject: Brake Fluids
In a message dated 6/8/04 6:19:38 PM, owner-fot-digest@autox.team.net
writes:
> Date: Mon, 7 Jun 2004 22:31:14 EDT
> From: GRMTim@aol.com
> Subject: Re: Dot 3, 4, 5 or 5.1
>
> We just did a big article written by a brake engineer on this topic in
the
> July issue of Classic Motorsports. The topic was covered very well.
The
> bottom
> line was to stay away from dot 5
>
> Tim Suddard
> www.classicmotorsports.net
>
There is more to this story than was covered in that article. Noting
that the
writer builds brake systems for race cars his perspective may be a
little
narrow.
Talk to the curator of any major car museum and you'll find that they
use Dot
5 silicone-based fluid throughout their collections for the same reasons
that
it should be considered for the individual hobbyist.
The fluid can be left in a non-driven car for long periods of time in
between
uses without any risk of rusting up the pads or clutch disc, it doesn't
have
to be changed frequently because it doesn't absorb water as quickly as
non-silicone fluid (note the higher temp rating of silicone fluid in
"wet" condition)
and, very important for expensive restorations, it won't harm expensive
paint
jobs.
It doesn't give as rapid pedal response as non-silicone fluid because of
the
larger bubbles so it certainly wouldn't be desirable for a car that is
raced
or autocrossed, but that is its primary limitation.
Two caveats -- silicone and non-silicone fluid can not be mixed because
the
combination negates all the additives in both types (and it is VERY
difficult
to completely remove all traces of non-silicone fluid from brake lines),
and
silicone fluid can break down the old-style natural rubber seals leading
to
brake system failure.
But, bottom line -- if you're not racing, and if you've installed a
completely new brake system (all seals replaced with modern materials
and all lines
replaced) in your restoration, you may wish to go the way the museums do
and
install silicone fluid in your car.
Cheers,
Gary Anderson
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