Conference oass::racers

    re: brake fluid
    
    Funny you should ask that question.  They just answered it yesterday on
    the "Inside Winston Cup" show on TNN.  I don't remember the exact name
    of the brake fluid but it was designed for aircraft use and has a very
    high boiling point.

Is there anything better than AP550?

My Pegasus catalog has -

Wilwood Hi-Temp 570 degree Brake Fluid

AP550 dry boiling point exceeds 550 degrees

AP600 dry boiling point exceeds 572 degrees (600 nominally). There is also
a warning that AP600 should not be mixed with any other type of brake fluid
and it is not DOT approved.

    I beleive the number given on IWCR was AP650...
    
    Paul

Apart from the boiling point is there any other differences?
E.g. Water absorbance?

            <<< MARVIN::DISK$TOOLS:[NOTES$LIBRARY]CARS_UK.NOTE;1 >>>
                            -< CARS_UK conference >-
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Note 1193.14                      Brake Fluid.                          14 of 14
VANTEN::MITCHELLD "A number, not a free man"         11 lines  24-AUG-1990 11:47
                        -< AP Racing Fluid statistics >-
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  Fluid type		Boiling temps in Degrees C
----------------------------------------------------------------------------
		New boiling point    Dry boiling point   wet boiling point
----------------------------------------------------------------------------
	AP550  |    295            |     290            |     145
----------------------------------------------------------------------------
	AP600  |    315            |     300            |     210
----------------------------------------------------------------------------

AP550 must be flushed out if AP600 is to be used.

    You MAY have to check on this, BE CAREFUL!!!
    
    From one of my brake manufacturer's, he tells me that DOT 3, DOT 5
    (Silicon), AP, Red....are NOT intermixable. Futhermore, your brake
    system may not tolerate certain fluids that it was not designed
    for. Why? The O-rings in the master and slave cylinders may detoriate
    ( DISSOLVE !! ) if used with with the wrong fluid. Some of the newer
    systems can handle all types of fluids. My Hurst-Airheart brakes, have
    2 diffrent part numbers for the rebuild kits. One for AP fluid systems,
    another for DOT 3 systems.
    
    	John
     

    I have been using the Wilwood Hi-Temp 570 in my 86 RX-7, which used to
    have DOT 3/DOT 4 fluid in it, with no ill effect.  I also know a bunch
    of other people who use this in their street (occational track) cars.
    
    -=Chong=-

I ve noticed  that on changing the fluid from DOT 5 to AP550 that the seals 
have swollen. I used an ordinary DOT 3 to flush the DOT 5 out.
 This has only affected the Master cylinders. I'm now soaking the
master cylinder seals in Dot 3 to see if they come back to normal.
Otherwise I'll replace them

I'm getting  dark murky fluid out after a race, is this normal?

No. The fluid should be the same color as when it went in. It sounds 
like there is something contaminating it. Every car should have all of 
the fluid flushed through the system periodically. Have you done this 
recently? If so, are there any old brake lines that may be 
deteriorating? You may want to take all of calipers apart and clean and 
rebuild them. It's usually not too big or expensive a job (but it is 
dirty).

I recently converted from dot 5 to AP550 brake fluid and have flushed the
system and have renewed all seals except the rear 
disk slave seals. This coloration
only takes place after a really hot race or practice. It also happened 
with the Dot5 fluid. As directed by AP I flush the system before each
race or practice.

All brake lines are copper or Goodridge/Aeroquip. I.e. PTFE

 The rear slave cylinders were on the way out and brake dust was getting in to 
the fluid. The cylinder have now been replaced ( at great cost)

    Do you folks have any opinion on copper brake lines.  I just read a
    tech article that they tend to get brittle due to vibration.  
    Any comments (I just bought new lines and they sent me copper).

    Copper is fine but it must be well supported i.e. each 200mm (8")
    is you cant do this install aeroquipe or equivalent. Yes they can
    get brittle if not supported.

    re .15
    
      If you ordered brake lines from a "race place" there is a possibility
    that you got copper plated steel lines. I have seen these before.
    Apparently the plating is for heat disappation. I sure wouldn't use
    regular copper for brake lines.
    
                               Jim