Having no personal knowledge on this subject, but recalling a passage from
Mathis' "Mustang Performance Handbook 2" -- which has a large autocross
chapter and several racing chapters -- I submit the following from its
"Brakes" chapter:
"FLUID -- Finally, unless you have the mega-dollars to flush the system
completely every time the car goes to the track, do not use silicone brake
fluid, and definitely do not use it on the street. This stuff sucks
moisture like regular fluid but does not keep it suspended. Instead,
moisture in silicone brake fluid pools and vaporizes into a large spongy
steam pocket as the temperature of the fluid passes water's boiling point.
Brake pedal feel becomes spongy and the differential braking gets weird.
Then, when the race car sits for a couple of weeks until the next race,
that pooled water creates a nice rusty pit inside the brake line, caliper
or master cylinder where it happens to settle. Again a most uncool
situation. Stay with the Ford Heavy duty brake fluid."
In my own experience, when I bled the brakes of the Mustang SVO that I
bought used last year, rusty fluid WAS expelled -- and I bled the brakes
because the pedal was low, the brake warning light was lit, and braking was
poor. So the above would make sense to me, and all's been OK since,
including autocrosses.
AM using silicone brake fluid, though. Uh-oh.
Richard Nichols
San Diego, CA USA
rnichol1@san.rr.com
86 Ford Mustang SVO (61B) - 1C
(The Thinking Man's Mustang)
72 Ford Pinto 2.0 (62B) - 3J
(Over Three Million Served)
----------
> From: rsmith@bfmni.com
> To: 'Karl Witt' <kwitt@shore.net>; 'Steve Hoult' <stevehoult@home.com>;
'John Lieberman' <johnlee@softdisk.com>; 'Eric Linnhoff' <eric10mm@qni.com>
> Cc: 'autox mailing list' <autox@autox.team.net>
> Subject: RE: Tiny bubbles...o...o....o....o.....o...
> Date: Tuesday, February 09, 1999 11:16 AM
>
> While were on the subject of brake fluid I wonder if the discussion can
> continue and answer some, what I believe to be, interesting questions.
>
> 1) I assume the big difference with the Ford fluid between wet and dry is
> that is has a higher propensity to absorb water (hygroscopic)! If that is
> the case how much percentage of water can Ford fluid absorb. How about
the
> other brake fluids. AND as far as the silicone based fluids - are the wet
> and dry the same since I've heard that they are not hygroscopic?
>
> 2) Water can enter the brake fluid from a few sources! A can left open. A
> can with little fluid in it that was opened on a damp day and therefore
has
> humid air above the fluid in the can. Through the rubber portions of the
> brake lines. When the cover is removed from the master cylinder to check
the
> level (mine is translucent but I still check visually by removing the
top).
> Assuming you used fresh from the can fluid, never took the cover off the
> master cylinder to check level and had sound rubber lines, just how long
> before the fluid would be saturated with moisture? (I have Teflon lined
s/s
> lines so I don't think I get any through the flexible bits.) I know this
is
> a very subjective thing - I'm just wondering!
>
> 3) Don't most racers who are competitive change or at least bleed their
> brakes quite frequently? Wouldn't this regular flushing/bleeding preclude
> using a more exotic fluid then the Ford spec stuff (that's what I use -
if
> it's good enough for Carroll Smith, etc.)
>
> BTW - maybe some have not heard of the story behind the Ford spec fluid
> (apparently it's not just available for trucks but cars as well).
Apparently
> Ford was having all kinds of warranty problems with brakes on their
Lincoln
> line of cars. Investigation revealed it was the median age of Lincoln
> drivers (older) dragging their left foot on the brake pedal causing all
> kinds of overheating problems (and no they weren't using left foot
braking
> to set up for the next turn!). Ford developed the fluid to counter this
> Lincoln problem and many are quite satisfied using it in all kinds of
racing
> vehicles.
>
> Many thanks for the excellent list of fluids and their properties. I've
been
> looking for this type of info for a while now!
>
> Racer Robb - rambling on a Tuesday!
|