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Thread: Brake Fluid

  1. #1
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    Brake Fluid

    When I bought the car, the owner was using DOT 3 synthetic. Is that still a good product to continue using? I plan on bleeding the clutch slave cylinder as what I have gotten out so far is pretty black.

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    Great Pumpkin TR3driver's Avatar
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    Re: Brake Fluid

    This is an often debated topic, with no clear winners. Personally, I much prefer DOT 5 silicone. It doesn't turn black, doesn't corrode brake components, and won't eat paint when it does leak (due to worn-out seals, etc). But it does have disadvantages too. You can read more about pros & cons at
    http://www.buckeyetriumphs.org/techn...luid/Fluid.htm

    That article references several technical papers, which you can find at
    https://drive.google.com/open?id=0B2...nhWS19scjlNUU0

    I particularly enjoyed the Browning paper, as it shows that conventional (DOT 3/4/5.1) fluid absorbs not only water, but salt; and can do so right through the hoses! It's no wonder the stuff becomes so corrosive over time!

    I've seen this multiple times (although never quite this bad). This was the clutch slave on TS13571L when I started reviving it from a 34 year hibernation.
    Randall
    56 TR3 TS13571L daily driver
    71 Stag LE1473L waiting engine rebuild
    71 Stag LE2013LBW waiting gearbox rebuild

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    Re: Brake Fluid

    Does DOT 5 mix with DOT 3?

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    Re: Brake Fluid

    They don't "mix". If the question is whether the system needs to be flushed of all 3 before starting the 5, there is some disagreement on this forum. The instructions on my fluid container said something like 'add the 5 and bleed til purple is coming out the bleeders'. I did and it has been fine for 5 years.
    Bob

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    Jedi Knight
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    Re: Brake Fluid

    Quote Originally Posted by bobhustead View Post
    They don't "mix". If the question is whether the system needs to be flushed of all 3 before starting the 5, there is some disagreement on this forum. The instructions on my fluid container said something like 'add the 5 and bleed til purple is coming out the bleeders'. I did and it has been fine for 5 years.
    Bob
    I did the same although I just finished my second year.
    I would also mention that the DOT 5 appears to be a poorer lubricant and my newly rebuilt and honed master cylinders are a bit slow to return. Not really a problem with the brakes but I can't "sped shift" with the clutch. I don't remember having the problem with rebuilt cylinders using DOT3 so I can only assume the DOT 5 contributes. I do plan to polish the bores before next season and continue using DOT5.
    Tom
    1960 TR3A TS73117 (under restoration year 6, owned since 1964)
    1959 TR3A TS58023 (in case I never finish the one above)
    1969 Triumph Herald 13/60 (a whim)
    1973 Buick Apollo (was Dad's car)
    1992 BMW325IC (fun to drive)

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    Yoda Geo Hahn's Avatar
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    Re: Brake Fluid

    Not only do they not mix -- but the distinctive purple colr does some strange things as shown here:

    http://www.buckeyetriumphs.org/techn...luid/Fluid.htm

    I have also just added the DOT5 to the system and bled until I saw it come through. The results have been fine on 3 cars - 18 years in one case.

  7. #7
    Yoda poolboy's Avatar
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    Re: Brake Fluid

    Empty the reservoir first, would be my recommendation.
    I absconded with a turkey baster for such duties.
    DRIVE 'EM IF YOU GOT 'EM

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