DNM Hornet (M200) seal replcement

Discussion in 'Running Gear' started by timeeh, May 10, 2014.

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  1. May 10, 2014 #1

    timeeh

    timeeh

    timeeh

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    Been riding round for the last few months with blown fork seals so decided it was time to chuck some new ones in. Anyway this is how i went about it, do not take this a gospel as i am certainly no bike mechanic.

    1) Get your tools ready
    [​IMG]

    I used a large adjustable spanner, a set of vice grips and a flat head screw driver. A vice is also very helpfull, but not a neccesity.
    And remove your fork leg/s
    [​IMG]


    2) Open your favorite beverage (some prefer to skip this step until completion, girls) However i maintain this is #1 thing to do b4 working on anything ;)
    [​IMG]

    Place the flat-head screw driver between your thumb and the cap (as shown) and remove the cap. I used a high strength home-brew, but you can take your pick.


    3) Once the fork leg is removed from the tripple clamps, start by placing it in a vice using soft jaws or improvise with a pice of tyre tube like i do, just stops any damage to the fork
    [​IMG]

    Using the adjustable spanner (or somewhere round a 24mm open ended spanner) remove the top cap off the fork leg
    [​IMG]


    4) Now the tricky bit, we need to remove the top section from the bottom. To do this get your vice grips ready then, place the leg upright on the bench (or on the ground) and pull the spring down,
    [​IMG]

    you will notice a slight notch in the stem which you then latch onto with the grips (I believe this can be done with the correct sized spanner but if it lets go, which it probably will, you may loose an eye, or 2)
    [​IMG]

    once done place the fork back in the vice


    5) Now you can remove the cap off the stem itself by unscrewing it.
    [​IMG]

    [​IMG]

    Once unscrewed remove the vice grips(carefully) and then remove the springs and the centre plastic seperator (comes out in the middle of the springs)
    [​IMG]

    Then you can sperate the fork leg, be carefull as the bottom of the leg will be full of oil.
    [​IMG]


    6) With the leg seperated, you can now remove the dust seal. This is done by using the flat head and placing it in the slots on the side (as in pic)
    [​IMG]

    then twist the flat head to pry the seal off the leg, then move around the leg using the same motion.


    7) OK we can now see the seal, first we need to remove the circlip which keeps it in place, which you can pop out just using the flat head.
    [​IMG]

    Now the seal can be removed, this is a little tricky as they are seated very tightly in there. Using the flat head place it between the top of the seal and the leg (as shown in pic)
    [​IMG]

    then slowy start prying it away, you may want to put a rag on the end of the flat head as otherwise this will damage your forks (as you'll see in the below pic :( )
    [​IMG]


    8) Now just do everyting in reverse :) To get the new seal in will take a little patience as the need to go in flush, so using your fingers start on one side and push it in a mm or 2 then slowly start making your way around it doing the same. You will prabably have a hard time getting the vice grips back on the stem after putting the springs on. There is not particular technique that i could advise just patience and perciverance here and a bit of "good luck". Or if you want to cheat, just go and buy yourself a set of spring compressors ;)


    9) (OPTIONAL) Once it's all back together you may wish to replace the fork oil. I normally use 185ml of 5w oil in each leg, and i add this just before screwing the top of the fork back on, just use a small funnel to sit between the springs and it will run down the inside of the fork.
     
    Last edited: May 10, 2014
  2. May 10, 2014 #2

    my67xr

    my67xr

    my67xr

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    + reps timeeh, good work !!

    but did you see this?
     
  3. May 10, 2014 #3

    my67xr

    my67xr

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    i think it should be made a sticky too !
     
  4. May 10, 2014 #4

    Cordogs

    Cordogs

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    Yeah top job Timmy! +reps from me too!
     
  5. May 10, 2014 #5

    timeeh

    timeeh

    timeeh

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    Yea mate :) But this ones seals rather than oil ;)

    And cheers for the reps fellas ;)
     
  6. May 10, 2014 #6

    gottagetacheaperhobby

    gottagetacheaperhobby

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    top walk through, +reps timeeh
     
  7. May 10, 2014 #7

    my67xr

    my67xr

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    yeah all good, it's got my vote for a sticky !
     
  8. May 30, 2015 #8

    toptoy

    toptoy

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    Great write up!

    But if you want to save some major grief just use a small 9mm open end spanner between the coils of the spring on the piston rod instead of grips as it will save you busting yourself trying to pull the spring down. If you have a painted/coated spring it will stop you chipping it when pulling it down & the chips falling into your tube. It will also make it a breeze to get end cap back onto the rod as it is nigh on impossible to get that spring down & keep the rod in the fully extended position to get the cap screwed back on - especially if you're running 2.5 wt oil like me. Watch out for small pieces of Loctite falling in as when you unscrew the end cap from the rod as they 'tite' them from factory - push some paper towel through the top tubes before you put them back together to make sure everything is super clean.
     
  9. May 30, 2015 #9

    my67xr

    my67xr

    my67xr

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    I don't understand what you mean with the 9mm spanner ?
     
  10. May 31, 2015 #10

    timeeh

    timeeh

    timeeh

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    I think i know what you mean but i can tell you there is f#&k all chance of fitting a spanner in-between the spring coils, could be wrong though, but don't think i'd have any chance of putting a spanner in there, also if i did once the top was unscrewed the spring would then spit the spanner in god knows what direction. But happy to be proven wrong, got pics of how you use the spanner?
     
  11. Apr 29, 2020 #11

    Dawson5567

    Dawson5567

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    I know this is an old post but I’m trying to do the fork seals on my DNA hornets and I can’t find anywhere that sells seals for them. Any help on where I can get them would be greatly appreciated. Thanks
     

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