Can this be done (brake fluid content)

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  • Can this be done (brake fluid content)
  • muckytee
    Member

    Now before anyone starts screaming “they weren’t designed for mineral oil – you shouldn’t do that” I know this, I am merely contemplating πŸ™‚

    If I had to flush out my Avid elixir 5’s with water and re-bleed with say Citroen LHM mineral oil – I assume they would work.

    Well the only problem as I see it is that the mineral oil may cause the seals to degrade.

    However would the seals degrade if they had never been in contact with DOT fluid, say if I had to replace all the seals?

    cheers

    Premier Icon shortcut
    Subscriber

    No idea on the real answer, but why would you not use the appropriate fluid?

    trail_rat
    Member

    not going to scream that but i will ask why you would do such a thing.

    infact thanks to an inept local bikeshop filling a customers brakes up with mineral oil i know that if you put mineral oil into a hope mini it causes the seals to swell and the brake to go exceedingly sticky.

    shops no longer in business now so you need not fear people of STW πŸ˜‰

    andyl
    Member

    seals are specified for certain materials. I’m a bit baffled by your thinking that they won’t degrade if not been used with dot fluid. If they say don’t use mineral oil then the seals will probably swell if you use mineral oil. New or otherwise.

    Just use some proper dot 4 (if that what they take) as it’s the cheapest fluid to use anyway.

    PS why are you flushing with water? Just flush with fresh brake fluid.

    trail_rat
    Member

    not going to scream that but i will ask why you would do such a thing.

    infact thanks to an inept local bikeshop filling a customers brakes up with mineral oil i know that if you put mineral oil into a hope mini it causes the seals to swell and the brake to go exceedingly sticky.

    shops no longer in business now so you need not fear people of STW πŸ˜‰

    muckytee
    Member

    Well, I won’t have to deal with corrosive DOT fluid for a start. Then I reckon that maybe mineral oil won’t have to be de gassed and also that it may have better lubricating properties, thus reducing sticky pistons.

    Really though it’s just an idea I am toying with.

    seals are specified for certain materials. I’m a bit baffled by your thinking that they won’t degrade if not been used with dot fluid. If they say don’t use mineral oil then the seals will probably swell if you use mineral oil. New or otherwise.

    I am aware of the consequence of using DOT fluid on seals designed for mineral oil, however since mineral oil is less aggressive than DOT fluid I am asking if it shall work the other way round.

    Just use some proper dot 4 (if that what they take) as it’s the cheapest fluid to use anyway.

    PS why are you flushing with water? Just flush with fresh brake fluid.

    To flush out the dot fluid before putting in mineral oil, I haven’t done anything yet, nor do I plan to, likesay I am just toying with the idea.

    andyl
    Member

    stop toying with it! The only way to get mineral oil in there safely is to replace all the seals and any other rubber/plastic bits with mineral oil safe parts.

    OR

    you could just use dot 5 (silicone brake fluid) which is fully compatible with dot 4 fluid systems and doesnt have any of the nasty traits of dot 4 (water absorption etc). The only problems are it’s expensive, will probably void any warranty you have, you will have to fully flush and clean the system first (not with water!) and if you have a leak it’s a real bugger to clean off (IPA probably won’t touch it).

    trail_rat
    Member

    dont think too hard

    i guarantee it wont reduce sticky pistons

    dot fluid doesnt need degassed either if your not an ork with the syringe – what do you think we did for years before sram came along as said “you must degass” ?

    and corrosive dot – in what way corrosive ? I’ve heard the storys but ive yet to experiance this corrosive property. its never done any damaged to my bikes or equipment in a number of years – infact i knocked a tub over on the wing of my land rover and it didnt even mark the paint.

    Also mineral oils just as bad for your skin and can be absorbed in just the same way – wear protective gloves and glasses just the same.

    andyl
    Member

    I am aware of the consequence of using DOT fluid on seals designed for mineral oil, however since mineral oil is less aggressive than DOT fluid I am asking if it shall work.

    it’s not that simple. What is damaging to one material is not damaging to another.

    The variation in chemical resistance between different types of plastics and elastomers is quite substantial.

    Brakes are pretty critical, maybe not a good idea to ghetto them. Just use dot4 and save a load of bother. Its all highly toxic anyway.

    sbob
    Member

    I’ve used water you pansies. πŸ˜€

    πŸ™„

    Premier Icon aracer
    Subscriber

    I’ve used water you pansies.

    Well at least you don’t have to worry about that absorbing moisture.

    sbob
    Member

    Excellent compressive strength as well.

    May not be sensible with the current climate…

    sbob
    Member

    sbob – Member

    I’ve used water

    …on someone else’s brakes, may I add. πŸ˜‰

    you could just use dot 5 (silicone brake fluid) which is fully compatible with dot 4 fluid system

    No, DOT5 is not compatible with DOT3, DOT4 or DOT5.1 whatsoever.

    matt1986
    Member

    The seals to fit your brakes would be made for dot not mineral and I reckon they would swell if you used mineral.

    Dont do it. It will fail. Trust me I’m a mechanic. We’ve had trucks towed in because the driver put the wrong fluid in the clutch.

    Rorschach
    Member

    Use tea.That way when your brakes overheat and fail at least you can have a nice cuppa (make sure you use semi skimmed though).

    bigyinn
    Member

    Darwin award nominee?

    Premier Icon Northwind
    Subscriber

    I use air. The only hard part is bleeding out the last brake fluid bubbles.

    Do it. But promise to come back and say we told you so. πŸ™„

    Orange Lad
    Member

    Comes close to the most silly idea I’ve heard in relation to brakes, the worst was the person who put 3in1 on their brake pads to stop them squeaking.

    legend
    Member

    (make sure you use semi skimmed though).

    so you dont gain unnecessary weight I assume?

    muckytee
    Member

    TBH I got the answer with trail rats post, which was that the seals will swell and evidence of this is from the real world. Not mere assumptions. πŸ™‚

    Rorschach
    Member

    Nice swerve there sir…I almost forgot about the stupid for a minute.

    bigyinn
    Member

    So unless you’ve had it happen personally your knowledge is invalid?
    So if I jump off a cliff I’ll be okay? Because I’ve not got first hand experience?
    You come on here, ask for opinions and then get snotty when people tell you it’s a stupid idea and you’re a bit silly for thinking of even trying it. Keep burying your head in the sand with your fingers in your ears going la la la can’t hear you.

    muckytee
    Member

    You come on here, ask for opinions and then get snotty when people tell you it’s a stupid idea and you’re a bit silly for thinking of even trying it.

    I’m agreeing that it’s a bad idea… but not because somebody just said it is, but because someone has provided an example why – it didn’t have to be first hand, I just wanted something more than: “it says use DOT fluid on them so use that”.

    I was writing from personal experience too…

    Call out to a broken down lorry.
    Clutch reservoir is full of bits of half dissolved rubber floating in the fluid.
    “Looks like someone’s used the wrong fluid”
    Embarrassed silence from the driver.

    Just leave the water in, should be reet. When the going gets steep, you’ll be able to make a brew at the bottom. That’s assuming you make it to the bottom, with zero braking.

    As already stated many times, you will ruin the seals and this will probably lead to poor brake feel and perhaps stop them working altogether eventually.

    Also theoretically flushing with water before changing the fluid is worse than just flushing it through I would have thought as mineral oil and water do not mix either. The water content will pool within the system.

    you could just use dot 5 (silicone brake fluid) which is fully compatible with dot 4 fluid systems

    This is actually incorrect. DOT 5 is completely different than DOT 3, 4 & 5.1 as it is silicone based whereas the others are glycol ether based. You don’t really want to mix the two.

    No, DOT5 is not compatible with DOT3, DOT4 or DOT5.1 whatsoever.

    This is actually incorrect. DOT 5 is completely different than DOT 3, 4 & 5.1 as it is silicone based whereas the others are glycol ether based. You don’t really want to mix the two.

    You can use 5 in a DOT,3 4 or 5.1 system, but you have to flush it thoroughly, and it’s crap, rather than absorbing water it let’s it pool at low points, where it then usualy corrodes through stuff, it’s also much more compressible so brakes feel spongy.

    Gets used in show cars as it doesn’t mark paint, and some military vehicles used it, sure they probably had a reason, fek knows what it was.

    barkit
    Member

    Northwind – Member

    I use air.

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