Marzocchi Fork Maintenance De-Mystefied?

Discussion in 'Trials' started by motobene, Oct 22, 2014.

  1. D2W

    D2W Been here awhile

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    325
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    Hmmm ... my understanding is that the inner damper rod which you removed is a valve which allows oil to bypass the shim stack/piston, and that's used to adjust the damping. I could understand that if you removed the inner rod then oil would come out. But that oil should only come out as a result of you moving the piston/rebound rod assemble down into the cartridge (as that would pressurize the oil and it would try to flow through the shims but it would find an easier path through the open valve [and then out the top]). But I'm perplexed that you say that after you put the inner rod back in place the damper rod rises. What's the source of the (pressure) energy that's causing it to rise? Is it just the weight of the fluid in the lower cartridge leg that's seeping into the cartridge? But that bleed hole is so small. Could the o-rings on your floating piston be compromised (and the oil is flowing into the cartridge)? I guess a simple test would be to remove the cartridge and hold it upright/normal and see if it leaks. Or does the damper rod still rise if there's no oil in the lower fork tube?

    I did see a post from Jim Snell/Hoss Cartright that he has a pair of Tech forks available; it's kinda spendy at $7900 but it includes a spare TRS One R I think. :)
  2. the toe cutter

    the toe cutter Been here awhile

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    Okay finally got power restored here. I didn't explain it correctly in my prior post, oil didn't come out until I removed the inner rod AND pushed the damper down. So not sure how helpful this test was :) Funny you mention the TRS, been looking into them lately.
  3. D2W

    D2W Been here awhile

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    Just had an "out of the box" thought to refilling/topping up the oil in the cartridge so that it's air-free and doesn't require disassembly. Dunno if it'll work. I'll try it next time.
    With the cartridge removed:
    1) Fully extend the damper rod.
    2) Remove the inner damper valve rod.
    3) Using a suitably sized piece of tubing, connect a (large) syringe filled with fork oil to the top of the damper rod.
    4) Invert the cartridge so that the small cartridge bleed hole is the highest point.
    5) Depress the syringe plunger to push the oil into the cartridge until the oil exits the bleed hole.
    6) Tape the bleed hole.
    7) Invert the cartridge to "normal"/upright.
    8) Remove the tubing/syringe.
    9) Push the (extended) damper rod back down to the bottom of the cartridge. Oil will exit the top.
    10) Reinstall the inner damper valve rod. >>> Do not pull on the damper rod. <<<
    11) Remove the tape from the bleed hole.
    12) Reassemble the cartridge in to the fork tube.
    13) Refill the fork tube with the correct amount of oil. >>> Now it should be "safe" to extend the damper rod. <<<
    14) Reassemble.

    Do you think this might work? And it may not even be completely necessary.
    jonnyc21 likes this.
  4. the toe cutter

    the toe cutter Been here awhile

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    East Bay CA
    Using the method above my clunk is now GONE!! Can't thank D2W and this thread enough for helping my get through this issue. I would also mention that the Hell Team in Australia has Marzocchi parts in stock if anyone else needs some internals, great people there. Two signs that you have air in your cartridge, at least in my case, was the damper rod rising up on its own and the mid stroke clunk versus just at top out.

    I did find out I'm missing a wave washer part #BT280614101 in the rebound stack (Hell Team stocks them) so will probably replace that at some point. Here is an exploded view of the stack if it helps anyone else.
    IMG_0630.jpg

    There is also a small top out spring deep inside the cartridge tube that normally doesn't fall out but I wanted to check everything to see how it works
    IMG_0637.jpg
    Finally, I'm 99% sure this is how the piston is oriented on the damper rod (pic was taken upon reassembly not removal)
    IMG_0631.jpg
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  5. Vintage pro

    Vintage pro Been here awhile

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    The last picture you post, is that the compression side?

    Attached Files:

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  6. D2W

    D2W Been here awhile

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    Hi Randy ... I'll do my best to answer ... Toe Cutter was having issues with the right/rebound side of his forks (with the sealed cartridge). So I would think that the piston in the photo is oriented correctly (with the bypass ports open on compression and the shim ports (?) effective on extension.
  7. the toe cutter

    the toe cutter Been here awhile

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    Thx D2W is correct -- rebound side. I pulled each item off the rod and placed them upside down on the blue towel starting at the bottom (locking nut).
  8. Vintage pro

    Vintage pro Been here awhile

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    O.K. the compression side is where I found the problem. Everyone I've have taken apart the piston was not orientated correctly, the piston was using the small holes of the rebound for the compression, which would make the fork feel harsh! It's what we call a compression spike.