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Dot 4-Dot 5 Can U Tell The Difference

Discussion in 'Motorcycle Tech Talk' started by Lucifer, Jul 10, 2008.

  1. Lucifer

    Lucifer Well-Known Member

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    I was going to top up the brake fluid on my 03 FLHPI and the master cyl cover said use Dot 4. I'm sure it wasn't until '05 when HD went to Dot4. Does anyone know if you can tell the difference by color, how it feels between your fingers
    (or tastes:roflmao:)
    I know they can't be mixed, so is there a way to determine which type is in there.:confused:
    The lever pressure is low, I jammed my forefinger between the lever and grip :eek: when I tried to stop using my middle 2 fingers to squeeze the lever(glad the rear brakes work fine) so it has to be addressed very soon.
    I really don't feel like changing master cyl and lines and decontaminate the calipers because someone may have put the wrong cover on.
    Any help is very much appreciated!!:devil:
  2. duke76

    duke76 New Member

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    take some of it out and put it on a scrap piece of metal with paint on it and if it takes the paint off it is dot 4 and if it doesnt it is dot 5. You are correct though they did not start using dot 4 until 05 Todd
  3. Lucifer

    Lucifer Well-Known Member

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    Right On Todd,:D simple answer,I should have thought of that. My rear M/C says Dot 5, just thought of checking that after I posted the question.
    I'm lovin this '03 Cop King ,altho it doesn't have the arm stretchin torque of my Evo. Yet!!;) The handling is head and shoulders above the Softail so now there are no sparks flying in the twisties.
    Thanks again man, you saved me a lot of work:D
  4. SPORSTERBOY

    SPORSTERBOY New Member

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    the dot 5 is a purple, at least the brand I got last time (napa) what makes it special is the silicone in it I guess.
  5. hotroadking

    hotroadking Super Moderator Staff Member

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    LOL I was going to say drop some on your fender, if after a couple of minutes the paint is still there, dot5

    Dot 5 is purple but can turn gold with age.

    If you have an aftermarket chrome cover on the front MC it could be for an older year, my 00 came with and has dot5

    You should be the same.

    You could flush the system anyway which is a good idea after a while and fill with fresh new dot5

    You only need dot4 if you have the abs system
  6. Lucifer

    Lucifer Well-Known Member

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    I dipped a clean cloth in it and rubbed it on my buds painted toolbox, paint's still there;) . Yeah HRK thats what I'm gonna do. The fluid has turned a gold color and it's probably been there since 03. It is a stock black cover on the front that said Dot 4, the rear has dot 5. So for peace of mind I'm gonna flush it with fresh dot 5, then put the correct cover on since there's about a dozen or so around here.
  7. cowboy

    cowboy Moderator Staff Member

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    sure glad you posted this , my 03 FLHTPI is about due for new B fluid with only 54-5K on the clock
  8. ringo912

    ringo912 Active Member

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    Dot 4 is a glycol based fluid and is hydroscopic, meaning it will absorb water. Obviously not a good thing to have in your break lines as it will cause corrosion of any steel components and the brakes will have a spongy feel.

    Dot 5 is silicone based, and non-hydroscopic. It will not absorb water and is the main reason the MOCO switch to it. However, it will absorb air and allow the air molocules to be suspended in the fluid. This will cause the brakes to feel spongy.

    As Lucifer said, you can not mix the two. If you do, it will turn into a nice liquid gel. When that happens you will be doing a total flush of your brake lines and a complete rebuild of your master cyclinders and calipers. Also the rubber seals in a Dot 4 system are a different material than those in a Dot 5 system.

    Depending on the environment and number of miles your ride, it is a good practice to completely flush and bleed the system with new fluid every 1-2 years. Some guy's I know do it every 10K miles. Condsidering the importance of the braking system, the $5 for new fluid and the 10 minutes to flush the system is cheap insurance.

    I would check your service manual for the correct spec's. As Chucktx always says, it's the most important tool in your box.
  9. hotroadking

    hotroadking Super Moderator Staff Member

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    One word for flushing


    Mity-vac

    or is that two words?
  10. ringo912

    ringo912 Active Member

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    Not sure if it's two words or not, but I agree. :cheers:
  11. Lucifer

    Lucifer Well-Known Member

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    LOL...Don't know if its 1 or 2 HRK but I'm gonna use it,and again on the fork oil.

    Musta been a shiny chrome piece there before I got it,which is fine 'cause I don't polish. Matte black is beautiful.:) :D
    After not quite 2 weeks and 1800 miles,I know why they call these bikes KINGS....just need more torque, which is coming soon!!;) .
  12. chucktx

    chucktx Moderator Staff Member

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    mity.vac= wonderful tool!!!!!!!!!!!!!!!!!!!!:) ;)
  13. SPORSTERBOY

    SPORSTERBOY New Member

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    your right, come to remember when I drained mine a o3, it was goldish,brown, and the dot 5 cost about 5 times more and harder to get cheaper.

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