Brembo clutch master with synthetic ATF

Discussion in 'The Garage' started by AUSSIEADV, Nov 6, 2019.

  1. AUSSIEADV

    AUSSIEADV 2wo left foots

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    G’day all,

    Im converting the Magura clutch master over to a Brembo clutch master.

    Magura use a mineral oil, the Brembo brake fluid.

    What im wanting to know, how would the seals cope with the likes of a synthetic ATF? I use ATF in the original mineral oil system just fine.

    I need knowledge rather than assumptions guys.

    The Brembo is for the Clake SLR im fitting.

    cheers all.
    #1
  2. BluByU

    BluByU Been here awhile Supporter

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    From what I know the seal material in a DOT brake fluid master cylinder are different than that of a Mineral oil master cylinder. If you use an oil based (synt or dyno) it will swell the seals, as the material is rubber based.

    But that being said, let us know if you try it. Always good to have real world proof one way or another.
    #2
  3. AUSSIEADV

    AUSSIEADV 2wo left foots

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    ill keep ya’s posted. I have assembled it so we’ll see.
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  4. mung

    mung Been here awhile

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    Use Dot 5 silicone fluid. It is inert so is good with all seals.
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  5. cagiva549

    cagiva549 whats a cagiva

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    Every bike I own runs type F ATF in clutch hydraulics . Type F is lower viscosity than modern ATF for smoother clutch action . brake fluid is nasty shit .
    #5
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  6. moparmiller

    moparmiller Been here awhile

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    So much wrong with this statement...
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  7. mung

    mung Been here awhile

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    Do not know if it would work on walruses. You can try it out.
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  8. steiny

    steiny Been here awhile

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    I would use what the manufacture says to use .


    Nothing else !
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  9. moparmiller

    moparmiller Been here awhile

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    Harhar, back to your statement that silicone oil is inert- it's not. It will turn Fluorosilicone seals into pasty goo. Skip the bad humor and learn how to use a materials comparability table.
    #9
  10. anotherguy

    anotherguy Long timer

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    Ditto. Been using it on my Tuono's clutch for a few years after getting tired of replacing fluid and seals regularly. Stays purple and lubricates the seals instead of allowing them to be chewed to little bits.
    #10
  11. mung

    mung Been here awhile

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    There are 14 bikes in my garage with many different brake and clutch systems. All have used Dot 5 for decades with no problems. Cannot tell you if any have fluorosilicone seals but brands include Brembo, Braketech, Nissin, Tokico, and probably others. Just my experience.
    #11
  12. foxtrapper

    foxtrapper Long timer

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    Viscosity is about the same, they both use the same base oil. Type F has no friction modifiers, Dexron does.
    #12
  13. LuciferMutt

    LuciferMutt Rides slow bike slow

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    What's wrong with just using brake fluid? It's what the Brembo equipment is spec'd for and it's hydraulic fluid -- for hydraulics. If you "want knowledge" why are you asking about using a fluid not spec'd by the manufacturer of the system? What advantage does ATF supposedly have over brake fluid?
    #13
  14. anotherguy

    anotherguy Long timer

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    My issue with DOT3/4 brake fluid is it's a poor lubricant for rubber. The clutch slave's duty is very different from the brake caliper. Brake pistons travel about .060"/1.5MM maximum. Clutch slave pistons travel much further and the seals don't twist they're stationary while the piston slides. This contributes to seal degradation as well as the fluid evidenced by it turning black quickly. DOT 5 is silicone based thus lubricity allows seals to live far longer and fluid life due to a dry boiling point of 500*F vs. 450*F for DOT4.

    The aforementioned Fluorosilicone seals are unlikely to be found in a motor vehicle hydraulic system thus rendering his pedantic point moot. :D
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  15. mung

    mung Been here awhile

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    The only downside to Dot 5 that I have found is that it does not absorb water. Regular brake fluid absorbs water and distributes it through all the fluid. If water gets into Dot 5 it will "pool" in areas and could lead to corrosion. For street bikes a once a year flush is good, for dirt a flush every 6 months works well.
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  16. AUSSIEADV

    AUSSIEADV 2wo left foots

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    Geeeez Mutt, did you read my post?

    ill give it another shot!

    The original hydraulic clutch system being Magura uses Mineral oil. The Brembo master uses dot 4/5.1. Now i have to use the Brembo master for the Clake SLR. So, i have a slave that requires mineral oil, a master that uses dot 4/5.1. Still with me?

    What im asking is, does anyone know if the seals in the Brembo, being brake fluid compatible, will withstand mineral oil ie the synthetic ATF?

    Now, as an update. Its been about 4-5 days and the clutch is still working fine. Will this continue i dont know.

    Another update. I have since found out that there is a kit avail to turn the Brembo into a mineral oil compatible master. Too late for the time being with the 3 day country ride this weekend.

    Nevertheless, for future info for others as reference id like to confirm with those who have had experience with this in the past.

    cheers guys.

    Al.
    #16
  17. AUSSIEADV

    AUSSIEADV 2wo left foots

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    Just feel brake fluid between your fingers! Not particularly Lubricious.

    I use rubber grease on my seals.
    #17
  18. ohgood

    ohgood Just givver tha berries !!!

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    atf ? I'm another hydraulic line ? no way ! unpossible !
    #18
  19. LuciferMutt

    LuciferMutt Rides slow bike slow

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    :fpalm

    Apparently this critical detail whooshed over my head, sorry. I see your dilemma now!
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  20. AUSSIEADV

    AUSSIEADV 2wo left foots

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    All good mate, you’re nearly as bad as me with my ‘speed’ reading!
    #20