Marzocchi Fork Maintenance De-Mystefied?

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

  1. the toe cutter

    the toe cutter Been here awhile

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    Little help here. I'm changing out the fork oil on my 2010 GG txt 250 with the Marzocchi's and have a problem with the rebound clicker. My forks do NOT have spring preload adjustments.

    Before I took off the fork caps I noticed the rebound adjustment clicker stopped "clicking" before it bottomed out. Meaning I turned it clockwise, I felt some clicks then it just kept screwing it without clicks until it bottomed. If I kept turning it counter clockwise I get about 33 clicks before it stops. It's been like this since the last fork oil change, but I want to fix it now. The compression side is fine, clicks all the way to the bottom and top.

    I backed out the rebound clicker all the way before taking off the fork cap. Here is what the rod looked like when I took it apart.

    To fix this problem should I back out the gold rod (#17 in post 1) or screw it in more? Maybe the silver cap nut is the cuplrit? Should the cap nut be totally tight or lose? It is lose right now.

    Here is what the rebound looks like? Then below that is what the compression looks like (it fully clicks so no problem with it).
    [​IMG]

    Compression (which fully clicks, no problems)
    [​IMG]
    #41
  2. motobene

    motobene Motoing for 49 years Supporter

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    Cap nuts with caps on should be tight.

    Not familiar with your problem, but can offer some thoughts.

    Clicks matter less than adjustment working right. Clicks offer tactile feedback but are not directly responsible for fine metering. Number of turns is another way to keep track of where adjusters are. O-rings can provide enough drag to maintain adjuster position.

    So, assuming nothing is functionally wrong with your forks, I'd adjust to where they work right and call it a day.
    #42
  3. the toe cutter

    the toe cutter Been here awhile

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    Thanks Motobene, good advice. There is a slight "clunk" on the rebound side which was there before changing the fluid but has gotten progressively more noticeable. I think I'm going to order some new bushings and go through both forks completely.

    Now that I have the refill procedure for the rebound cartridge outlined in this thread, I don't feel as intimidated.
    #43
  4. Hatch

    Hatch Perpetually lost

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    btw, talked to charlie while at TTC training days and his suggestion for the marzocchi 40mm forks is 300-330cc of 5-10wt (he mixes to yield 7wt) per fork. I (tried) used the measuring method outlined earlier in this thread and blew one of my brand new seals at the training days. this time around I will be going with Charlie's suggestion.
    #44
  5. You can buy 7.5wt fork oil.... (Motul for instance)
    #45
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  6. Barnman

    Barnman Been here awhile

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    Breaking it down, the clicks are caused by a ball bearing and spring in the top cap. The ball bearing ‘clicks’ into those vertical slots just under the top o ring on your picture as you screw the adjuster up or down (counter clockwise / clockwise).


    When you turn the adjuster clockwise, it is pushing on a rod inside the tube which pushes on the bypass needle. The bypass needle is spring loaded, so you are pushing it against the spring to close the bypass, and the spring pushes back when you open the bypass valve


    Having understood that, you have a few possibilities


    1. The ball bearing is not smoothly running in its hole. The ball bearing is held by a spring and allen key which can be seen on the side of the top cap. Easy to check, just be careful not to loose it as it springs out it if you decide take it out. Probably not your problem as you say you do have some clicks. So,
    2. The top cap is not threaded onto the rod enough, so that when you close your bypass valve by screwing the adjuster down (clockwise), you lower the clicker slots past the ball bearing so it no longer clicks. The top cap should be fully screwed onto the rod. Check that (part 24) is not impeding the top cap when you are screwing the top cap on. Quite possibly your problem.
    3. As a check, take the brass adjuster out to reveal the rod. You should be able to push this against the spring and see it return. Check that this is nice and smooth.

    Hope this helps you
    #46
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  7. mung

    mung Long timer

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    I use 10 wt. on the compression side and 5 wt. on rebound side, both 15 mm higher than called for. Fork is slower on compression and still quick on rebound. Works very nice being a larger rider[6-5,250].
    #47
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  8. laser17

    laser17 Long timer

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    Do you use the stock fork/rear spring?
    #48
  9. mung

    mung Long timer

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    Stock fork spring but I am one step stiffer spring on rear and it made a big difference.
    #49
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  10. I'm curious if you ended up using this method... my forks are due for an oil change and I'm debating tearing them down all the way or not.
    #50
  11. the toe cutter

    the toe cutter Been here awhile

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    Motobene or other experts, would you recommend changing the internal fork bushings on the Zokes?

    I have almost 300 hours on my 2010 GG Pro 250 and have been doing regular fluid changes. Forks feel okay but wondering if it is time to change them out?

    Thanks!!
    #51
  12. motobene

    motobene Motoing for 49 years Supporter

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    Forks are so much better designed these days. The kind of wear one might see 40 years ago such as the chrome plating on the stanchions worn through to the nickel and even steel, is rarely to be seen.

    If things are tight and still look good, an oil change or two should suffice.

    The part these days that can degrade obviously is the upper seal, the dust seal. That can be changed without fork disassembly.
    #52
  13. the toe cutter

    the toe cutter Been here awhile

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    Thank you motobene, I'll split the forks next time I'm doing a fluid change and take a look at the bearings. Don't want to tear them down more than I need too after reading your thread about the bleeding procedure :)
    #53
  14. motobene

    motobene Motoing for 49 years Supporter

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    Welcome.

    Over the years I've learned suspension internals dirty up and wear much more slowly than long ago, even if the oil gets dirty. In that case, multiple changes can get you back to virgin clean oil.
    #54
  15. DerViking

    DerViking Shred

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    Resurrecting this excellent thread. I have Graydog's 2014 Gasser. Fork started showing a scrape along the front edge of the rebound side, looks like the bushing is wearing on the slider. Not good.

    Got through disassembly with a little concern, but fairly straightforward. Little things, like the fork caps will stick halfway unthreaded, and require a wrench again, had my freaked out for a little while.

    Fork tubes and bushings pulled right out, without pulling the oil seal, much to my surprise.

    So, oh wise internet, how do get the seal out without damaging anything? The seal is done, but I wouldn't mind extracting it intact for the practice.

    Once the seal is out, how do I get the bushing out of the interior of the fork leg? From what I can see with a flashlight, the bushing is cocked sideways in the bore, and that is why it is wearing on the fork tube. The other leg looks fine, as well as the bushing on the slider. Once I extract it, i'll post pictures. Can't get enough light into the bore to make my camera focus.

    I've been flushing everything with ATF, as I have lots, and its cleaning properties have always amazed me. Not sure if i'll reassemble with ATF and run it awhile, or if I should get proper fork oil. ATF sure is affordable.
    #55
  16. motobene

    motobene Motoing for 49 years Supporter

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    I never did get deeper into the later model GasGas Zokes, so I don't know some issues in detail. If you suspect deeper problems with things like bushings, it seems a full disassembly for direct visualization is called for.

    A cocked bushing seems odd.

    As for the black-stuff coated aluminum stanchions, I've been amazed at how much abuse they can absorb without leaking. Some of that is no doubt due to the excellent SKF seals.

    Those 2014 forks are still being used on today on the Scorpa SC standard version, as Sherco bought the remaining inventory after GG's crash. I've seen some apart at RYP, so maybe there are some parts available - if you need some - in a dusty bin somewhere?
    #56
  17. DerViking

    DerViking Shred

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    I agree the coating is impressive. But there was a little wad of it scrapped off the tube and sitting against the bushing. I'm hoping it will sand up.

    Looks like I can get the bushings from Splat shop, 10 lb each, plus shipping. SKF seals are available from a US Ebay seller, about $30 per leg.
    #57
  18. motobene

    motobene Motoing for 49 years Supporter

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    Wow, a wad of coating peeled off sounds ominous!

    It's obvious and maybe goes without saying, but it helps to rotate the stanchion rods to where the abused areas are toward the back or back-inside, presenting fresher coating on the higher pressure front side.
    #58
  19. DerViking

    DerViking Shred

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    Exactly. Its a testament to Graydog that he hasn't had to have the forks out of there for anything. I end up playing with the tube height often enough that I think they get shifted regularly.
    #59
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  20. DerViking

    DerViking Shred

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    Pulled it all the way apart. Couldn't figure out how to get the bushing out, as the upper tube clunked a couple times, then popped right out, leaving the seal, washer, and bushing in place. Pried the seal and washer out. Someone mentioned heat, so I got the lower tube good and hot, then slipped the upper tube back in, and was able to use it to pop out the bushing. All this after a great deal of searching. No one talks about the bushings, as I take it they just pop right out with the slider on most forks. The other bushings look good, but as they were able to pass inside of each other, I am replacing all of them.

    It definitely wasn't sitting right:
    IMG_20170805_124747146_HDR.jpg
    But I think it was just cocked, not miss bored. We'll just see how the bleeding goes.
    IMG_20170805_124800062.jpg
    #60
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