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  1. #1
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    How to: Fix your stuckdown 07/08/09 Marzocchi 55/66/888 ATA fork: Pics

    Hi all

    Well here is my little how to that shows you how to teardown a ATA cartridge and give it a bit of TLC. If your ATA Cartridge is stuckdown, this guide will show you how to remedy the problem. MODS, sticky this if you wish

    ================================================== ===============
    WARNING: Im not responsible for any damage you cause to your fork, persona or surrounds. This repair is simple if you have some mechanical inclination and common sense. Care must be taken as these Carts can contain air at VERY high PSI's, undo something the wrong way and you'll have yourself a pretty dangerous speargun.

    Righto now the legal Bull$hit is outta the way, onto business!
    ================================================== ===============

    First what is a stuckdown ATA cart?
    Your cartridge is stuckdown if it does not return to full extension despite:
    1- Winding the ATA knob to max extension
    2- Pumping ridiculous amounts of air in the ATA chamber

    Also, another potential give away is if your ATA chamber appears to be losing pressure and the fork keeps creeping down in its travel.

    Well first off, here is the likely cause of your stuckdown problem (shown with my awesome paint skills )



    Now I performed this fix on a 888 ATA WC, but I dont see any reason why it wouldnt work for 08/09 55/66/888 ATA forks, and also for 07 66 forks, the only difference would be the cart size.

    Only tools needed for this job is a 12mm socket (for the 888), shifter, o-ring pick, and fork oil, also handy to have some drip pans and rags...

    Right, time to get back full travel

    ================================================== ===============

    STEP 1:

    First, deflate all the air from both the ATA chamber and PAR assembly, remove your fork from your bike and pull out the ATA adjuster knob (dont forget to set it to max), if you dont know how to do this i suggest you put the tools down now, also, in the case of the 888, its best to remove you crowns aswell.



    STEP 2:

    Next lay the fork down flat, then using a 12mm socket (in the case of the 888), undo the ATA footnut. Now when the nut disengages the threads there will probably be a loud clank and the cart will fire up into the lowers, dont panic, this is normal on a stuckdown fork. Some oil will also probably spill out, be sure to wipe it up, then pour the remaining oil into a drip pan.





    STEP 3:

    Next, using a cassette lockring tool, undo the ATA top cap and lift out the entire ATA cart




    STEP 4:

    Have a friend firmly but gently grip the cartridge body with an old tube, then using a spanner or shifter, SLOWLY (and I do mean SLOWLY) start to undo the ATA cart. THIS BIT IS CRITICAL, IF YOU DONT DO THIS BIT CORRECTLY, YOU'LL HAVE A CARTRIDGE BODY/SHAFT FLYING ACROSS THE ROOM. Undo the cartridge VERY SLOWLY until you start to hear air seeping out, when you hear this, STOP UNDOING THE CART. This is where all that air you were mysteriously losing has gone, and when you tryed to pump the cart back up, you added to it. Wait until the air stops coming out, then undo and remove the cart. If you hear air being sucked into the cart when you are pulling it from the body, this is a dead give away that your o-ring was undersized, it is bleeding into the vacuum within the cart. When you pull the piston out, you may suck up the PAR assembly, this is normal.





    STEP 5:

    You have now taken apart the ATA Cartridge, lay all the parts on the table and give them a good wipe. Should you wish to perform Renegades PAR removal mod, now would be the time.



    STEP 6:

    Now the undersized (or frayed/damaged) o-ring that is causing your problems is the one on the right. To fix this, go down to a local o-ring supplier and get a few o-rings that are slightly larger. You may also wish to replace the other visible o-rings, take them aswell and have them sized, its also best if you buy a couple of each, always good to have spares!



    STEP 7:

    Once you have replaced your o-rings, drop the PAR assembly back into the cart (dont worry if it dosent fully seat at the bottom, it will when you pump it back up. I like to pour about a cap full of 5wt oil into the cart to keep everything slippery smooth, also lube up the piston and o-rings, then reinsert it back into the cart. Use your spanner and tube and tighten her up, dont get heavy handed on the torque, the threads are made of Aluminium.




    STEP 8:

    Congrats, you have service your ATA cart. Now reinstall it back into the fork and check the marz website for your forks oil volume in the ATA leg, fill the oil and pump her back up, and if you have done everything correct, welcome back to full travel!

    Now make sure you dont go hucking the 40 foot gaps just yet, take the first few rides easy to make sure that all the internals are properly lubed and bedded in.

    I performed this fix on my mates 888 ATA WC about 5 months ago, and it has worked flawlessly ever since (5 months of DH/FR) so the fix works.

    SUCCESS = BEER

  2. #2
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    Excellent! Thanks for sharing.
    Presently rocking the 888 ata wc on the Yeti. It's the '09 model. I only have two rides on the fork so far.

    Positively going to print this out and save to file.


    Thanks again.
    ~Rudster~

  3. #3
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    I don't ride Zokes but nice work!

  4. #4
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    Nice job Nick!

  5. #5
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    You are a lifesaver, thanks for the easy to follow instructions! Now to crack open that 55 again

  6. #6
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    Cheers for the props guys!
    Have fun fix'en your forks!

  7. #7
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    The one most critical step of this is: thread the seal head back into the ATA body with the piston TOPPED OUT. If you don't, the wind down will continue right where it left off, or close to it.

    Additional warning: MAKE SURE THE CARTRIDGE IS DEFLATED BEFORE YOU OPEN THE SEAL HEAD. CHECK TWICE. Otherwise you will have a Marzocchi projectile inserting itself in the wall on the other side of the room, or in you, whichever happens to come first. Not really, but it will still shoot the cartridge apart once you unthread it with air pressure in the cart.

    Also: it's easiest to break the top cap loose from the stanchion while it is in the crown. Those things come WAY too tight from the factory, and undoing it by hand with a tube sucks.

    When re-assembling, you can keep the cartridge from spinning by pressing down on the top-cap to tighten the footnut.

    You also only need about 4-5ml of lubricating oil below the main piston, and 1-2ml above.

    Give the inner walls, and ALL sliding surfaces of the cartridge a really thorough cleaning and lubricating.
    805

  8. #8
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    Quote Originally Posted by DHidiot
    When re-assembling, you can keep the cartridge from spinning by pressing down on the top-cap to tighten the footnut.
    Thanks for that tip, that was one of my biggest concerns, was just watching that spin and spin with no way to tighten it

  9. #9
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    Cheers for those ad ons DH, good call on the technique to tighten the footnut, I didn't give it a thought because my footnut tighten up without the cart spinning

  10. #10
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    Yeah it just depends how clean the threads are. Once the o-ring is contacting you're usually ok.
    805

  11. #11
    Nightmare on Lyrik st. VI
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    I don't have a Marzocchi and I don't even plan to own one. But damn, I still read the whole thread. I love your How To's. Keep them coming.
    Quote Originally Posted by TNC to whining spammer
    Don't let the nose of your saddle hit you in the @#!#X on the way out.

  12. #12
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    thank you

    very helpfull, really you simplifyed my life,
    I got an 2009 66 ata new with this problem an now I know how to fix it. Never used it yet.

    thanks again

  13. #13
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    Nice how to guide. Also if you replace that top out bumper (in the neg air side) with the updated o-ring you will have a larger neg volumn and a suppler intitial stroke. I see yours is 08 so not sure why its not there but maybe yours is really early. If yours is really early there is another o-ring that is actually inside the threaded aluminum part of the ata system and that o-ring got replaced with one of a thicker wall to prevent air from escaping and going into the stanchion, so not sure what you have in there either.

  14. #14
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    Very nice guide, easy to understand even for a noob like myself.

    I was going to send my sticky 07 66 ATAs off for service but with your guide I think I might just give it a bash myself

    Only thing is I will need to find a local o-ring supplier but that shouldn't be too much of a problem.

    Now to see what Renegades PAR removal mod is all about

  15. #15
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    Perfect timing!



    My 55 ATA just bit the big one last sunday.. checking with Marz to see if they will do it, since it was just done in April of this year.. and has not really been ridden that hard this year.. maybe 2 rides per month at most.

    If not I'll be diving in with the wrenches! This doesnt look that hard

  16. #16
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    I tried the fix last night, but couldn't get the cartridge apart. I will machine myself a clamp and try again tonight.
    The problem I have is different to what you list. I have a 0766SL ATA and a 08 55ATA, and both of them are losing pressure from the cartridge, and it's leaking into the fork leg, so when you undo the top cap it releases the pressure. I assume that this fix will address this issue too?

  17. #17
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    Hi mate
    Yes it should fix the problem, id reckon the leak is coming from the threaded end cap on the ATA chamber (the chamber top cap) Just do a replacement of all the seals and you should be ready to roll again

  18. #18
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    Quote Originally Posted by Nick_M2R
    Hi mate
    Yes it should fix the problem, id reckon the leak is coming from the threaded end cap on the ATA chamber (the chamber top cap) Just do a replacement of all the seals and you should be ready to roll again
    I took it apart tonight, as far as I can tell, the o-ring inside the top cap is the offender, when I took it out, it has a seam on the inside, so I will find a new o-ring tomorrow and let you know.

    Edit: I took it apart, and the offending o-ring was the internal o-ring on the top cap of the main cart. body. (the one that the cartridge piston slides through.) It's held pressure over night and through a bunch of cycling, but I need to get out and ride it to test the fix. The offending o-ring had a nasty seam on the inside of it, which is why I believe it wasn't holding air.
    Next, I tackle the fix on my 55.
    Last edited by Biggles604; 01-29-2010 at 01:26 PM.

  19. #19
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    thanks a million for this guide!

    I tore down mine a while back and got about to the point of potential springing across the room and stopped because of hearing the air and feeling the cartridge having some spring in it and then gave up for fear of causing irreparable damage, and i needed the bushings done anyway so just sent it off.

    Great to have a full guide to doing it myself!

  20. #20
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    What size o-ring do you think it fits best? I think originally it has 18.72x2.62, 19x3 is too big 18x3 is too small, 19x2.5 leaks, what do you guys use?

  21. #21
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    Quote Originally Posted by Mosquito
    What size o-ring do you think it fits best? I think originally it has 18.72x2.62, 19x3 is too big 18x3 is too small, 19x2.5 leaks, what do you guys use?
    The main o-ring for the stuckdown problem is a size 116, if you are losing air around the shaft, then the internal o-ring for that is 114.
    The 100 series o-rings are all 3/32" thick. if you wanted to go for a slightly oversized o-ring, then you need to go thicker, not a larger diameter. The closest o-rings are:

    # ID OD w
    114 5/8 13/16 3/32
    207 9/16 13/16 1/8
    208 5/8 7/8 1/8

    116 3/4 15/16 3/32
    210 3/4 1 1/8
    209 11/16 15/16 1/8

    For the 114 you want to maintain the same OD, so the 207 is the better choice. For 116 you want the same ID, so 210. With the thicker o-ring, the fit will be really tight, and may be stickier and require a softer o-ring.

    For the fix, I looked at this option, then thought about it carefully and decided to go with stock o-ring sizes. I've now repaired a number of forks, and realised that most of the time, it's contamination of some kind that causes the failure, be it a bit of dirt, a hair, metal shaving. When you re-build, inspect the o-rings carefully, chances are fairly good that you won't have to replace them, just clean then, clean the assembly and carefully reassemble taking great care to maintain cleanliness and you should be good.

  22. #22
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    Im having problems with getting the ata lock nut at the bottom of the fork off. I tried to loosen the top of the ata side first via the cassete tool but it seems like that cartridge is just spinning in there. Ive done this before when my ata wasnt blown, now its sittin with an inch of travel and cant be extended, and just made sure to put pressure extending the fork to get the nut off. Any tips to remove that lock nut?

  23. #23
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    Quote Originally Posted by billyzane
    Im having problems with getting the ata lock nut at the bottom of the fork off. I tried to loosen the top of the ata side first via the cassete tool but it seems like that cartridge is just spinning in there. Ive done this before when my ata wasnt blown, now its sittin with an inch of travel and cant be extended, and just made sure to put pressure extending the fork to get the nut off. Any tips to remove that lock nut?
    Hmm.. that is strange, seeing as putting pressure in the cart to extended it normally jams the nut enough so that it loosens.

    Perhaps try having a friend help you with this method
    Have him/her invert the fork and hol it with the steerer touching the ground, have them push down on the crown assembly will pulling the lowers up via the arch, grip it round the bases of the arch as theres more meat there.

    Failing this, try again after heating the footnut gently (AND I DO MEAN GENTLY, just till its hot to touch...) with a propane torch, then try and get the bugger off

    let us know how it goes!

  24. #24
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    I tried to pump up the cart back to what i ride it at 100/80 and tried what you mentioned above and its still free turning. I know this shouldnt be this hard to do !

    Do you think an impact wrench will have enough torque to grip the threads of the bolt and take it off? Or is this going to f up more stuff then i would want?

  25. #25
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    Alright was able to get the nut off the bottom by compressing the fork and using an impact wrench to torque off the nut. Rebuilt the cartridge and feels great, full travel back! Thanks for the write up.

    I did notice I can adjust the travel though, the knob doesnt want to turn in any direction. Did I forget the first step in turning the travel adjustment to max before doing the rebuild? Dont really want to monkey with it now because it works great, ill fix the adjustment problem if it is the case of me screwing up step #1

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