Marzocchi Fork Maintenance De-Mystefied?

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

  1. mayoisnasty

    mayoisnasty trials wannabe

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    Apologies for the resurrection. :pope

    A few questions for the experts here. I don't know why I have had so much trouble. I've done this job before, albeit on old dirt bikes and street bikes many years ago. Been off bikes for quite some time. Anyway, I began to replace seals and fluid on the left side (thought it would be a cinch) and found something unexpected right off. When I was separating the two halves to remove the seal, the lower bushing stayed in place leaving the top bushing, washer and seal in place. Is this a problem? I went ahead and reassembled as I figure parts for these are non-existant.

    I filled the fork back up with oil with a 6" air gap as motobene described and reassembled it. I worked out all the air (I thought), but when I have the fork in my hand and invert it I can hear a gurgling sound from the oil running to the other end. Also if I bump the fork against the heel of my palm lightly, the spring clanks around inside. I disassembled, drained and filled the fork up again with the same result. What am I missing? If I'm struggling this much with the left fork, I am reluctant to tackle the right side.:baldy

    edit: yes, the spacer is in there :lol3
    #81
  2. mayoisnasty

    mayoisnasty trials wannabe

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    I am used to there being holes here to work out trapped air.
    20200524_155407.jpg
    #82
  3. lineaway

    lineaway Long timer

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    You have not mentioned what you are working on other than it`s a fork.
    #83
  4. mayoisnasty

    mayoisnasty trials wannabe

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    It started out as a simple seal kit. Now I am trying to get oil back in it to a correct level, air removed and have the fork feel like it should. I have triple checked myself three times. At this point I am just going to take them both to a suspension shop.

    Edit- marzocchi 40 mm. Left fork leg. Open cartridge. Seems all the past talk (including this thread) I can find is about the right side closed cartridge fork.
    #84
  5. the toe cutter

    the toe cutter Been here awhile

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    Need some help from the experts here to see if what I'm hearing is the rebound air "clunk" or something else? Tried bleeding the rebound cartridge as per the directions in this thread AND a second time using the Hell team method, still getting a clunk on full rebound. YES I make sure NOT to stroke the damper road until it's in the fork leg with fluid added. Otherwise the fork feels fine.

    Listen and tell me if this is the clunk people talk about or is this normal for Marzocchi forks? Brand bearings although forks do have 415 hours on them (2010 GG 250 pro).


    Here is sound they make on bench AFTER going thru bleeding ritual, adding fluid to fork leg and adjusting proper air gap (160mm) before I stroke the rod (sounds bad).


    Seriously considering a set of Tech forks as you can't get internal parts for the Zokes anymore.
    #85
  6. D2W

    D2W Been here awhile

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    For what it's worth, I just replaced the oil in the 'Zokes of my '08GG using the Hell-Team procedure and I do not hear what you're experiencing in your forks.

    >>> The following is pure guess-work on my part, so be careful in what you read in to this: <<<
    I too was wondering what could cause a "clunk" if the inner cartridge was not correctly purged of air, and I figured that if the cartridge had a sufficiently large air pocket the piston would stroke through the air upon rebound. At this point the rebound would be ineffective and some other stop (which limit the extension) would be hit at a higher speed/force, and that would make the "clunk". Again, I don't know if this is correct.

    But it's very odd in your second recording that you can get that "clunk" at many points in the stroke of just the damper rod. And you certainly are not using much force. :hmmmmm

    Could it be that you did not tighten the cartridge mounting bolt at the bottom of the fork sufficiently, and you're hearing the bolt hit the tube bottom? ... Nah, that doesn't make sense because you're not pulling up on the damper rod. But ...

    Why is your damper rod rising on its own like it's pressurized? I certainly don't remember mine doing that. The rod should resist movement, but I don't think it should move on its own.
    #86
  7. the toe cutter

    the toe cutter Been here awhile

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    Thanks D2W, yeah cartridge bolt is torqued to 23.5nm. I think you are on to something with the damper rising up on its own, might post on trials central to get some input.

    For reference, the difference I found between the bleeding procedure in this thread vs Hell Team is that in this thread I pulled the damper rod all the way down before adding any fluid. See pic below as I mimicked his setup.
    [​IMG]

    The Hell Team describes/says to start filling the cartridge with the stack set ABOVE the tube (see pic below). Again tried both ways and still have clunk. So frustrating, would love to know what's causing it.
    upload_2020-8-14_16-52-45.png

    This video describes process same way as Hell Team in terms of pushing damper rod UP through cartridge before you add fork oil
    #87
  8. D2W

    D2W Been here awhile

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    OK, so in the Hell-Team procedure, the statement "Fill the forks completely with oil ...." should more correctly read "Fill the cartridge completely with oil ...."

    I minimized the amount I drew the piston into the oil (as this would maximize the volume in the cartridge occupied by the damper rod). If you were to draw the piston to the (normal) top of the cartridge (i.e., maximum extension) then you would be able to completely fill the cartridge with oil. Then when you lowered the damper into the cartridge you would be pressurizing the oil (due to the volume of the damper rod. I don't believe that very tiny bleed hole would allow the oil to depressurize sufficiently). So perhaps this is why your damper rod tries to rebound when you depress it in your videos. I would think you want a neutral operation of the damper rod.

    And just for completeness, when you reinserted the bottom floating piston (with the bleed screw), you did resecure the bleed screw? And then the spring and bottom mount and the final circlip?
    #88
  9. the toe cutter

    the toe cutter Been here awhile

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    Yes sir, had the floating piston at 60mm down from cartridge then pushed it down another 10mm (to 70mm) and THEN screwed in phillips screw with oring. Then spring and bottom mount then circlip and pulled up on bottom mount to make spring captive.

    RE filling the cartridge during the bleed process, you are saying to try only pulling down on the damper rode (it's upside down in wood jig) far enough to get the floating piston, spring and bottom mount in correct? This of course after I have added oil to the cartridge.

    Really appreciate your help and time!
    #89
  10. D2W

    D2W Been here awhile

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    No worries ... I'm happy to try to help as many others on this forum have helped me plenty.

    If I remember correctly (I mostly followed the Hell Team procedure):
    Once I had it mostly all apart:
    1) I inverted the cartridge and tape/plugged the small bleed hole.
    2) I filled the cartridge with oil to the bottom of the (open) big holes.
    3) I drew down on the damper to draw the valve assembly into the cartridge. I pushed the valve assemble slightly beyond the bleed hole. >>> From this point on I did not move the damper rod. <<<
    4) I topped up the oil (to the big holes).
    5) I removed the bleed screw from the floating piston, and then inserted the piston so that it was just below the big holes/oil level. I may have pushed it alittle bit beyond the big holes but not as far at the bleed hole.
    6) I reinstalled the bleed screw.
    7) I installed the spring, the bottom plate which receives the fork-tube bottom bolt, and the circlip.
    8) I removed the tape which I used to plug the bleed screw.
    9) I inserted the cartridge into the fork tube, and secured it with the bottom bolt.
    10) I filled the fork with oil and set the level from the top of the compressed upper fork tube.
    11) I then drew up on the damper rode and secured the fork cap. Make sure you fully back-off the damper rod jam nut so that you're able to fully thread the fork cap onto the damper rod. And then move the jam nut to the cap to secure the assembly.
    12) I then drew up the upper fork tube and threaded it onto the fork cap.

    I think that was about it.

    Any chance that your valve assembly somehow became loose/unthreaded? I would think it should be secure on the damper rod.
    #90
  11. the toe cutter

    the toe cutter Been here awhile

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    Great instructions, easy to understand. Double checked that the shim/stack "valve" was tight on the damper rod and it was. So I disassembled and reassembled again, but no luck...still has clunk. That leads me to think something internal is worn out or broken. I've read two threads now (one linked below) that talk about a broken "wave washer" as the possible culprit. I do remember years ago when I did a fork service, can't remember if it was comp or rebound side, but one of the thin washers was split in half so I removed it. Who knows. I did NOT stroke the damper rod to see if it returned back on its own as I wanted to follow your instructions to the tee.
    https://trials.com.au/forum/viewtopic.php?t=9947

    Going to just ride it and see maybe if it selfs bleed like Motobene mentioned in the first post. Again, thank you for the help D2W. If I do find a solution I will definitely post here so that it might help someone else.

    Pic of how far I pressed down the floating piston (The phillips screw WAS REMOVED when I pressed it in. Pic was taken just before I put in the spring)
    IMG_0596.jpg

    Spring going in just before installing the bottom plate and circlip.
    IMG_0595.jpg

    Measuring fork level
    IMG_0597.jpg
    #91
  12. D2W

    D2W Been here awhile

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    Sorry to hear that you still have the issue. :hmmmmmDoes it still make the noise when you manipulate just the damper rod? Does it still seem to be pressurized when you release it after depressing it?
    Referring to the exploded parts diagram (I believe Motobene has a copy in the very first post of this thread), I sure don't see any parts which would "clunk".
    25 is the circlip
    68 and 69 are the bottom mounting plate/seal
    67 the spring
    63-66 comprise the floating piston and bleed screw
    26, 27, 62, 34, 33, 35, 31 comprise the valve. 26 might be the "wave washer" as the drawing looks kinda "wavey". All of those elements should be secured onto the damper rod and held in place by the nut/31

    Hmmm ... I can't remember if you can do this, but can you (carefully) extract the rebound adjustment valve/17 from the rebound adjustment rod/20? If so, does the system still make the clunk? Perhaps this valve is somehow moving when you move the rod?

    Another thought/guess ... if you grasp the valve assembly, can you move the rod/20? I would think that the valve would be securely fastened to the rod. If there is movement between those two pieces that might be the source of the noise.
    EDIT: I just reread your recent post and you indicated that your valve stack was firm on the damper rod. :thumbup

    And i have a question for you as I don't fully understand myself; what does keep the fork from flying apart on extension? Is it that the damper rod becomes fully extended? Or does the upper slider hit something in the lower fork tube? I guess I could block the front wheel at maximum fork extension, and then remove the fork cap from the damper rod. If I can pull-up on the rod beyond the "maximum extension" position I can infer that something in the fork tubes is limiting the extension. And it I can't then it's the damper rod. Does that seem logical?
    #92
  13. the toe cutter

    the toe cutter Been here awhile

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    I didn’t want to touch the damper rod so not sure if it’s still raising up on it’s own.

    Pretty sure what keeps it from flying apart is the bolt at the bottom of the forks (screwed into the cartridge) and the top cap. The upper stanchion is NOT what tops out first, but that was a good guess.

    if after riding it for say 10 hours and it still clunks, going to pull it again and see if the damper rod still raises on its own. All the while looking for used set of tech forks LOL.
    #93
  14. D2W

    D2W Been here awhile

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    You should be able to test your damper rod "pressure" in situ; just loosen the upper triple clamp bolts, loosen the fork cap, compress the forks, take off the cap, manipulate the rod. Not too messy. :-)

    Ok, so if the cartridge assemble is what limits the extension (and that sounds reasonable), then it does make sense that if there was an air pocket in the top of the cartridge then a clunk would be produced if the piston/valve stroked through air before it hard-stopped at the top of the cartridge. There would be no damping before the piston smashed into whatever is internal to the cartridge.

    But in your videos you're getting a click/pop/clunk when you're mid-extension. Your piston/valve is no way near the top of the cartridge. :hmmmmm

    So the source of your clunk doesn't seem related to an air pocket/incorrect bleeding procedure.

    Dunno if riding it for 10 hours is going to make a bad situation better. :dunno
    #94
  15. the toe cutter

    the toe cutter Been here awhile

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    Too hot here to work on bike :( competition tomorrow but have my ‘17 txt for that. Will give what you mentioned a try and let you know.

    Just bounced the front end and you’re exactly right in that the “clunk” is not just at top of rebound stroke. It can be felt/heard about half way back up too.
    #95
  16. D2W

    D2W Been here awhile

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    #96
  17. motobene

    motobene Motoing for 49 years Supporter

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    Not all clunks are from air in the cartridge. A loose internal part can happen. But if the clunk is directly after an oil change where the cartridge was not disassembled, it's from air.

    If you have a stable bike that is in a good state of maintenance and has not been run decades on the original oil (read: not nasty paste for oil), the way-above-described method of refreshing the oil only around the cartridge instead of trying to replace all the oil is a godsend. Just remember, don't stroke the rod when the oil isn't around the cartridge, even though you'll be like a vampire looking at that rod like blood, wanting to do it!

    Like changing automatic tranny fluid in cars and trucks, you change only some of the oil, not all of it, and that's goodnuff. And if you need to do it again, to get clearer oil so what? You can do that on a trials bike one armed and half asleep.

    A clunking problem on a 2010 Gas Gas Econo I had with Sachs closed cartridge forks where it took about 3 hours of hard riding to finally clear out the air pocket, plus messing with the blankity-blank Marzocchis is what got me into the lazy-man trick.
    And since it's become my go-to methods. No monkey-business bleeding required.
    #97
  18. the toe cutter

    the toe cutter Been here awhile

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    If I can resolve the clunk issue (started long after my last fluid change) definitely doing the refresh method you outlined Chris. At a local event yesterday I tested two marzcocchi forks and mine "feel" the same just that I have the clunk.

    I appreciate the link D2W and I'm watching trial breakers for any used Tech fork or if an internal Marzocchi comes up. Confirmed today that you have to buy the entire internal cartridge if you want any of the parts like the teflon seals, wave washer, etc. Still over 100 here next few days but will try to get fork apart and make sure that valve is totally tight on the damper rode (where shim stack is located). I checked the nut last time and it was not lose at all.
    #98
  19. D2W

    D2W Been here awhile

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    Happy to hear that your fork still felt the same despite the clunk. Perhaps, as Chris suggests, it is an "air pocket" thing and it will eventually purge itself. Hey, regarding the nut on the valve shim stack; it may be tight because it's bottomed out on a step on the shaft, and so there still may be movement of some of the valve components. And you might be hearing this movement. Just a total guess on my part. So check the valve thoroughly. I love a good mechanical mystery.

    Not sure about this, but I thought that Marzocchi was still active in mountain bike suspension products, and that some components may cross over. Dunno.
    #99
  20. the toe cutter

    the toe cutter Been here awhile

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    @ D2W, took fork off and yes the damper rod still rises up on its own like it's under pressure (still makes the clunk noise like in my previous video). So I tried pulling out the threaded brass adjustment rod and it DOES NOT rise on it's own or make clunk sound. It spurts fluid out the damper rod top (where brass adjustment rod was) so I probably introduced some air into the closed chamber. Put the rod back in and still rises on it's own/makes clunking noise.

    Next step will be to disassemble and completely take apart valve stack to see if there's anything broken in there. Will give me chance to reassemble and make sure everything is tight. Will add pics/video to this thread in a minute to help show what I mention above.