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  1. #1
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    FAT Mr Dirt Triple Bypass help

    Hello chaps
    This is a long shot I know...but does anyone have service experience with these forks?
    I suspect they are 1999ish....with the spring lhs and oil damping rhs
    Mine isn't damping...I suspect it just needs new/more oil etc
    Any help[ available?
    Picture available if it helps
    Cheers
    Carl

  2. #2
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    I have the Quad Bypass (just the number of ports on the bypass...should be the same as the Triple).
    They're unbelievably simple to work on. These forks also don't loose oil so if it worked before, and now it doesn't, I suspect the nut that retains the piston/shim stack has worked itself loose and fallen off. If no damage, some loctite should fix things right up. If the shims are damaged, just get some new ones from the moto shop. I believe the shim stack is used for compression, while the dial that adjusts the bypass ports is intended for the rebound.
    Just open it up and take a look. They're unbelievably simple to work on, and yet work so well.
    Naysayers never apologize. Critics go to their grave thinking everyone else is wrong.
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  3. #3
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    Thanks P...much appreciated
    I am very inexperienced with fork servicing ... shall I just undo the hex bolt at the bottom...and see what falls out?
    Cheers
    Carl
    Edit...oh and do you know which oil and how much to use?

  4. #4
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    Quote Originally Posted by Harryburgundy
    Thanks P...much appreciated
    I am very inexperienced with fork servicing ... shall I just undo the hex bolt at the bottom...and see what falls out?
    Cheers
    Carl
    Edit...oh and do you know which oil and how much to use?
    Taking that "hex" bolt out will only allow you to remove the dropout and drain the oil from the open bath model. In the case of the IFP Quad Bypass, it won't even let you do that. All of the internals are accessed from the top. Us a pin/spanner tool to undo the top cap. Once you've slid the leg down a bit, you'll see a neoprene "shield". Be careful here, there's trapped air under it and can pop and spay oil everywhere. In the case of the side w/ the rebound adjustment (the bypass ports), you won't need to undo the knob first, unless you want to get into the bypass adjustment (there's no real need to get into this as there's nothing to break in there).

    As for oil level, on the damper side (I think the open bath model has the spring on that side too?), go by feel. With the top cap not threaded on the leg, compress the uppers till you can see the stanchion. Fill and cycle the leg till you see the oil completely fills the stanchion, submerging the piston/shim stack. Then, bolt everything together and cycle the fork. You shouldn't feel (or hear) the fork all of a sudden leave the oil (it'll make a slurp noise) and "jump" up when you push it down and let go. If it makes that noise, open it again and add more oil. Once it reaches the point of no slurp noise, you can add more for bottom out resistance. For the dummy leg, just add a bit of oil to keep things slick and bolt back together (no knob side).

    Rinse the leg and your hands w/ soap and water before you do the push test, in case you didn't fill it as full as you thought and the fork "jumps" up, slips thru your hands and clocks you in the eye.... The IFP version has the spring and damper legs separate so it can get pretty dangerous doing the push test on an undamped spring leg...ahhhh Krazy Glue is your friend for sutures that leaves no scars
    Naysayers never apologize. Critics go to their grave thinking everyone else is wrong.
    ╭∩╮( . )╭∩╮

  5. #5
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    Brilliant.....much appreciated

  6. #6
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    I thought this was one of those "John Q Mountain Biker is getting a Triple Bypass Heart Surgery tomorrow, give him ur munniez!"

    I'm kind of disappointed

  7. #7
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    Feel free to donate....I'll pm my paypal details

    Pictures










  8. #8
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    Pretty good for giving instructions from memory ehy?

    That dummy leg can also take oil to adjust the bottom ramping. I bought like two of these forks, one was Mark Wier's old IFP fork, and the other is the open bath one...just to have some spare parts. People were giving these forks away after Barnett (Mr. Dirt) stopped making them. I mated the IFP leg to the open bath's damper leg to get compression and rebound control...by flipping the piston and shim stack in one of the legs (can't remember which leg tho).

    Nice WF VR1! I was lusting after one, until I found Karpiel's Disco.
    Naysayers never apologize. Critics go to their grave thinking everyone else is wrong.
    ╭∩╮( . )╭∩╮

  9. #9
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    Pretty good for giving instructions from memory ehy?
    Not too shabby ;-) thanks once again , much appreciated

  10. #10
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    Quote Originally Posted by Harryburgundy
    I remember wanting one of these real bad. Nice!
    Quote Originally Posted by kidwoo
    The internet sounds like a tough place to ride.

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