Type Of Brake Fluid

Discussion in 'Technical Help' started by Foxy1, Mar 25, 2020.

  1. Foxy1

    Foxy1 Crème de la Crème

    Aug 31, 2018
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    Whilst I'm servicing mi calipers and changing mi pads, I'm also changing t'brake fluid. I see DOT 4 is recommended for my 2011 speed Triple. Are there any advantages to using DOT5.1, or would I just be wasting my money?
     
  2. Callumity

    Callumity Elite Member

    Feb 25, 2017
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    The only material difference is their boiling point so unless you are racing you and your bike could never tell the difference. Your wallet might.
     
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  3. topbanana0

    topbanana0 Well-Known Member

    Mar 27, 2016
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    Really don't think you should use dot5, as its silicone based. And should not be used with abs systems.
     
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  4. Foxy1

    Foxy1 Crème de la Crème

    Aug 31, 2018
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    I don't have ABS.
     
  5. topbanana0

    topbanana0 Well-Known Member

    Mar 27, 2016
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    I didn't read your first message properly, didn't notice you said dot 5.1
    Which isn't the same as dot 5
    Personally I would use what the manufacturer recommends.
     
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  6. Foxy1

    Foxy1 Crème de la Crème

    Aug 31, 2018
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    OK chaps, just as a thought. I used 5.1 when I raced, but obviously not needed on t'road.
    Are all t'brands t'same, or should I go for a "name", ie Brembo or Castrol, or is it all t'same standard?
     
  7. Erling

    Erling Elite Member

    Dec 12, 2017
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    You could have a look here, for what it might be worth:
    https://www.caroutfitter.com/best-brake-fluid-reviews/

    Personally I haven't given it much thought, except that on my cars, I prefer to alternate between yellow and blue just to make sure I have got all of the old fluid out.
     
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  8. MARKYMARKTHREE

    MARKYMARKTHREE Senior Member

    Feb 11, 2020
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    I believe you shouldn't put DOT 5 in a system that has previously had DOT 4 in it, even if you think you have flushed it, as it goes gloopy. When I restored my MK3 Cortina 10 years ago I completely replaced the braking system and put DOT 5 in it. I have bleed the system twice since then and what came out was exactly the same purple colour that went in. DOT 5 is also paint friendly unlike 4.
    Top tip time, use DOT 4 for striping paint from plastic parts as it wont damage the plastic. ;)
     
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  9. TimmyTheHog

    TimmyTheHog Member

    Feb 20, 2020
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    1. Do not use 5.0

    2. unless you are taking the bike off to track/race/always slamming the brake like mad, you will not see the benefit of 5.1 since the real benefit of 5.1 is higher boiling point.
     
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  10. Helmut Visor

    Helmut Visor Only dead fish go with the flow
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    Oct 3, 2018
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    Hello Timmy, and welcome in :cool::cool:

    You say "Do not use 5.0" but with no evidence or explanation as to why not. It's kind of like me putting on the What are you Drinking Tonight thread "Do not drink white wine" but without explaining that it is a fruit based cocktail designed specifically for the ladies ;);)
     
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  11. TimmyTheHog

    TimmyTheHog Member

    Feb 20, 2020
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    Okay okay, i guess I can see that lol.

    you shouldn't use 5.0 as it is silicon based while 3/4/5.1 are glycol base therefore are not compatible with 5.0.

    From my understanding, 5.0 also does not play well with ABS system.
     
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  12. Big Sandy

    Big Sandy WOOF! WOOF!

    Nov 14, 2018
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    Fuck off you nosy cunt
    From my understanding DOT 5 is not hygroscopic where the previous numbers are (which also effects the boiling point)

    The two do not mix, obviously if you add 4 to 5 then you allow it to absorb water as well, and it sludge. If you wanted to use DOT 5 then you would need to start with a new system, with zero traces of 4.

    Main advantages of 5 over 4 are the higher boil point, not hygroscopic, and there is generally less corrosion of brake cylinders and damage to seals.

    I have heard the same about Abs, I think it's to do with abs systems being calibrated to work with non silicon fluids, I think dot 5 compresses differently.

    DOT 3 is standard, DOT 4 is heavy duty, both are glycol based, so strip paint where DOT 5 is silicon, and won't strip paint.

    Bit of a yawnworthy post... I did a fair bit of research when I rebuilt the Land Rover brake system, was going to use DOT 5, but in the end there weren't enough advantages to justify three times the price of DOT 4.
     
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  13. Tricky-Dicky

    Tricky-Dicky Crème de la Crème

    Dec 12, 2016
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    I have gone from dot4 to 5 (silicone based) there is no problem with interaction and goop as one is different SG to the other and will sit on top/below cant remember which right now no significant difference in feel though.
     
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