Brake fluid change interval car vs motorcycle

Discussion in 'The Garage' started by Project84, Oct 10, 2017.

  1. eastbloc

    eastbloc comprador bourgeois

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    On my 2014 Ural the rear brake starts to drag when it heats up if I don’t change the fluid once a year.
    #81
  2. quickstang87

    quickstang87 Adventurer

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    So riddle me this. If you never changed the brake fluid in your motorcycle that you rode every day, will it cause any kind of real problems over the long term?

    I think that is partly why automobiles can get away without flushing the brakes every year or so, because most of them are pretty often on the move. The average bike sits way more than it moves, especially over the long term. When those parts sit, that is when things stick, corrode and start to have real problems.

    I had an '89 VTR 250 that I bought years a go. The brakes worked ok, but when I took the front apart and cleaned out the caliper, the fluid had the consistency of baby food. The bike had less than 20K miles on it.

    On the other hand, last year I bought a 2010 Harley that had been sitting for at least 5 years and the brake fluid looked fine. I did flush it out, but it sure looked fine to me.

    I changed the brake fluid on my daily rider about 6 months ago. At the time it was 2 years old and had about 30,000 miles. Honestly, the only reason I changed it is because I put steel braided brake lines on.
    #82
  3. dwayne

    dwayne Silly Adventurer Supporter

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    I would suspect some f the varied results come from varied climates. I suspect, all other things being equal, brake fluid lasts longer in the high desert than, say along the gulf coast?
    #83
  4. aldend123

    aldend123 Long timer

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    In theory, it causes corrosion. I'm not sure how much water content you'd need to see noteworthy rate of corrosion though.

    And of course eventually you may decrease the boiling point of the fluid to discover it at an inconvenient time. The boiling point drops pretty quickly as it absorbs water.
    #84
  5. Jack90210

    Jack90210 quia ego nominor leo

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    Never thought of this. Thanks.
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  6. karter18

    karter18 Been here awhile

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    Brake maintenance is really a preventative measure to keep the system in good working order after all it is your braking system. Usually do the fluids at least every year on the bikes and 1-2 on the cars depending on use. Track car every year for sure if not more. Bikes are so easy to do with one person I usually do all of them with the Fluid left over from doing the track car as I just opened it. Did the truck the other day with the one person plastic bottle hose method and it worked great. Suck old fluid out of Master. Plastic bottle with an air and hose hole in the lid. Fill 1/3rd with old fluid and put bleeder hose into bottle higher than caliper. Other end of hose to caliper and crack open and pump the brakes several times until new fluid comes out. Worked great and brakes feel solid and no helper needed.
    #86
  7. MotoChris521

    MotoChris521 expert apprentice

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    All brake systems are vented to atmosphere . Just as fuel tanks are vented . Simple physics .
    brakes-and-braking-system-27-638.jpg
    #87
  8. H96669

    H96669 A proud pragmatist.

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    Them "one man bleeders" work on the same principle as the bottle/tube method.Cheap too....$5.00?

    I think I have a more expensive version?Has a magnet on the bottle to mount it close to the bleeders?

    If you are doing bleeds on anything DO NOT slam pedals/levers to end of travel.In some cases it may damage MCs.Old car guys trick was a block of wood under the pedal to prevent it from going all the way down.
    #88
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  9. concours

    concours WFO for 47 years

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    Yes, many times
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  10. Donkey Hotey

    Donkey Hotey De Jo Momma

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    Actually, no. See the red thing under the cap? That's the rubber diaphragm. Without it the fluid would be garbage after a week of humid weather.
    #90
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  11. MotoChris521

    MotoChris521 expert apprentice

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    Well aware of the diaphragm . And the vented portion is between it and the cap/cover .
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  12. Donkey Hotey

    Donkey Hotey De Jo Momma

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    Right but, the fluid is not touching the atmosphere. It's a condom for your brake fluid.
    #92
  13. MotoChris521

    MotoChris521 expert apprentice

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    Ah Ha ! But do the rubber components totally seal out the atmosphere ? Um, no .

    It is designed to absorb water! Diffusion allows moisture in the air to permeate microscopic pores in the rubber brake hoses and the various seals in the hydraulicbrake system. ... This feature comes at a cost, which is, that water contaminatedbrake fluid reduces its performance.

    Just like a tire looses air pressure over time .
    #93
  14. dwayne

    dwayne Silly Adventurer Supporter

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    Your exact words were "all brake systems are vented to atmosphere". That does not happen. Despite being somewhat permeable the diaphragm is most definitely not a vent. The expansion chamber is vented, but the entire system, and especially not the fluid chamber is "vented" in ant traditional or technical definition of vent.
    #94
  15. MotoChris521

    MotoChris521 expert apprentice

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    FFS . Where did I say the entire system is vented to the atmosphere ? All brake systems have some type of vent in the master cylinder cap . Is that better ?

    A reservoir diaphragm for a vehicle brake master cylinder fluid reservoir has a passage in communication with the atmosphere defined between the reservoir cover and diaphragm. The diaphragm has a slot receiving a projection from the cover to normally form a seal. The seal prevents passage of air between the reservoir and the passageway when the reservoir substantially equals the atmospheric pressure. The diaphragm is movable with respect to the projection to open the seal when the pressure in the reservoir is less than the atmosphere thereby allowing air from the atmosphere to enter the reservoir.
    #95
  16. Disston

    Disston ShadeTreeExpert

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    The master cylinder on my car is sealed with a rubber diaphragm that shrinks into the reservoir as the fluid is depleted. Happens slowly but the depleted fluid was exposed to the air. Every time I open the reservoir to check the level it is exposed to the air. I've added another dose of water to the fluid.

    Brake fluid absorbs water from the air. It takes longer with modern systems but it can not be stopped. MY 43 year old motorcycle also has a rubber diaphragm in the cap of the MC. Same thing as my 8 year old car. I think I flush the brake fluid more often on my bike for some reason.
    #96
  17. Disston

    Disston ShadeTreeExpert

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    Actually modern master cylinders use a diaphragm to dispalace the fluid that has been lost. This has been the case since the 1970's I think. But the air does get in too especially if there is a leak in the system.
    #97
  18. dwayne

    dwayne Silly Adventurer Supporter

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    Ffs yourself:

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  19. aldend123

    aldend123 Long timer

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    Not all materials are of equal permeability. Just because it's rubber and a tire is rubber, I don't think that means they have equal properties. I'd hope that the diaphram seal was made of something that offered maximum moisture impermeability.
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  20. Project84

    Project84 I can haz adventure?

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    I must admit, I kinda made this post in jest to call upon the ridiculousness of brake fluid change intervals on motorcycles (and those of you who feel so proud of yourselves for doing them once a year) and how 99.99999% of all commuter vehicles never get a brake fluid change throughout their lifetime... unless you lose a brake line/caliper.... and even then chances are most people would refill the system, bleed just that line, and be done.

    So, today I salute you, Mr. Proactive Motorcycle Enthusiast Who Neglects All The 4 Wheeled Machinery Guy. Squeeze those brakes and revel in all that steamy ceramic glory. Who can stop you? YOU can stop you. You can endo by mistake and brag about it, because your bike's brakes are JUST THAT GOOD, but that van full of kids with the absent minded soccer Mom cutting your commuter SUV off has not a snowball's chance in hell. So crack open an ice cold Bud Light and stand proud, Mr. Proactive Motorcycle Enthusiast Who Neglects All The 4 Wheeled Machinery Guy, cause this one's for you. :beer
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