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XJ900RK Anti-Dive stripdown how-to with pics...

Discussion in 'XJ DIY How-To Instructions' started by 750E-II_29Rbloke, Dec 5, 2013.

  1. 750E-II_29Rbloke

    750E-II_29Rbloke Active Member

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    Copyright 2013 750E-II_29Rbloke All rights reserved, may be linked/copied/saved or otherwise modified by author's specific written permission only. :roll: :wink: (Forum owner & moderators have my permission to do anything they want with it!)

    So I remembered to pick the camera up while I stripped one of my bike's Anti-Dive fork valves (just the fork side for now but I'll add the brake side when I get to it), so I've decided to make a sort of "how to" pictorial guide of the stripdown that may be of help to others. This stripdown covers the XJ900 RK (31A model) type, although other models MAY be similar...

    Firstly after removal from the bike (2 hex bolts to separate it from the actuator part & 2 more to remove it from the fork leg, fork oil must be drained first but it's not necessary to drain or bleed the brakes at this stage of the job, just tie the actuator up so it doesn't hang by the brake hose) it's a good idea to pop the adjuster cap off if it's still present, remove the split pin from the adjuster screw & give it a soak with penetrating oil as it's likely to be tight if not seized. Don't worry at this point if the screw slot is buggered, it's not the end of the world as we'll see later. :wink:

    Removing the split pin...

    [​IMG]

    Now get rid of those nasty old O-rings as they're 30 years old and WILL leak if you don't kill them with fire now and try to re-use! Gently pry them free with a screwdriver or toothpick, being careful not to gouge the metal if you use a screwdriver.

    [​IMG]

    Now VERY CAREFULLY as I'm not sure if you can get replacements (ask chacal at XJ4Ever if you need them, if anybody has parts for these he has!) pry out the dust seal from the top of the unit which will expose....

    [​IMG]

    ... this circlip...

    [​IMG]

    ... Removal of which will allow the retaining collar, O-ring (throw it!), plastic top-hat bush, piston and spring to come out (you may need to gently push them out from inside, especially if the piston is seized into the collar)...

    [​IMG]
    [​IMG]

    Now give the innards a quick squirt of your favoured penetrating oil to clean off the claggy old fork oil and you will be able to see this wire clip...

    [​IMG]

    VERY carefully pry this out...


    [​IMG]

    Because the washer below it is coated with rubber & again I don't know if this is available (chacal again, if it is :wink: ) so use extreme caution removing this if it's tight, ideally use a wooden or plastic toothpick to work it up out of the unit and be aware it can catch in the groove that the wire clip came out of, another reason for making sure everything's clean so we can see what we're doing...


    [​IMG]

    Once the rubber coated washer is out, this spring is free to be removed also & we're nearly there...

    [​IMG]

    Now we see why the adjuster's screw head being damaged is not completely devastating to our work, there is another slot on the inside end of the adjuster...

    [​IMG]

    Once more donning our extremely careful hat, we can now start to slowly work the adjuster back & forth while adding penetrating oil until it is free enough to unscrew all the way IN to the unit (all the parts except the adjuster's rubber cap & split pin come out through the top)

    This is what the adjuster screw looks like, again throw away the O-ring and fit a new one as it'll leak otherwise...

    [​IMG]

    This is what we are now left with, all the parts laid out in order...

    [​IMG]

    And that's all there is to it, the fork side of the Anti-Dive unit in it's entirety. Simple really isn't it! 8) So now you've seen what they consist of, fear the Anti-Dive no more, shun the "blanking kit" and get stuck in. The most common problems I think you'll find with this side are oil leaks, damaged/seized adjuster and seized piston.

    All these can be dealt with fairly simply & easily once the unit is stripped, but again be careful with the parts since (O-rings aside) I don't know if spares are available. Damaged adjuster heads can be got around by adding a shallow new slot in the end using a dremel-type tool, and reassembling with antiseize on the threads.
    Oil leaks will undoubtedly be cured with new O-rings.
    And a seized piston can be worked free from the collar with judicious use of penetrating oil, pliers with tape/aluminium protected jaws &/or drifting out. Antiseize shouldn't be needed here but if the dust seal is damaged/missing it would probably be a good idea to pack the gap between fork side & brake side with silicone grease or similar to keep water out in future.

    Any questions please feel free to ask, any omissions or corrections feel free to tell me & I'll sort it out. I'll get into the brake side of the units next time :D
     
    chacal and Core like this.
  2. 750E-II_29Rbloke

    750E-II_29Rbloke Active Member

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    OK think I'm finished editing the text in now... Anything you're unsure of, feel I've missed, or just got plain wrong please do tell, I want this to be as useful as possible :)

    Just adding some tags to help searchers... Anti Dive Antidive Anti-Dive dive valve A D A-D fork repair rebuild XJ900RK 900 RK 31A (reminds me of those ebay listings you see, except these tags are actually relevant to what I've written!) :roll:
     
  3. kinen1

    kinen1 Member

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    This is now in my Favorite bar!

    thanks 750E-II_29Rbloke.

    kinen1
     
  4. adrian1

    adrian1 Active Member

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  5. z32800

    z32800 Member

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    Cant wait till mine need done; you've made it nice and easy! cheers 29R Bloke :)
     
  6. 750E-II_29Rbloke

    750E-II_29Rbloke Active Member

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    That's a nice one, should be closer to what kinen1's units look like 8) Been getting nasty migraines again lately so I've not had a chance to play with the actuators yet but we'll see what this next few days brings & try to get some progress made there...
     
  7. Jaedee2

    Jaedee2 New Member

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    Hey team, jumping onto this thread with a question on my anti dives out of my 83 xj900rk seca.

    I've stripped down and rebuilt my entire forks, I won't be rebuilding the anti dive units, however I have replaced the 2 o-rings that attach the units to the fork leg, however after filling both forks with new oil they are leaking from the unit. I've triple checked I'm tightening to the required 7nm torque and the 2 o-rings are brand spanking, I've drained the oil, checked both surfaces and completed filling the forks with oil 3 times now, yet they still leak.

    Getting to the point now where I'm thinking of gasket glue!

    Any tips/pointers would be really appreciated!

    Cheers,
    Jamie
     
  8. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Where did you get the o-rings from?
    My first thought is that they are not of the correct thickness.

    Were the forks filled with oil and not leaking from the anti-dives prior to the rebuild?
     
  9. Jaedee2

    Jaedee2 New Member

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    Grabbed the o-rings from a box in the workshop - 12 x 2.5s

    Forks were fine and dandy prior to tear down
     
  10. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    The o-rings tend to be made from thicker cord than is usually in a commonly available set.
    Does about half of an o-ring sit proud of the anti-dive body?
    Did you notice any scratches or pitting on any of the mating surfaces, or in the recesses for the o-ring?
     
  11. Jaedee2

    Jaedee2 New Member

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    Hey team, so I grabbed the exact o-rings off megazip and installed them. Still leaking, the left fork worse than the right. I noticed if I held a flat bar on both piston housings that they were not flat?? So weird as these forks were not leaking prior to strip down and powedercoating. After getting an oil stone on them and running figure 8's I managed to get them flat, but they're still leaking.
    I'm at the point of welding them shut. If anyone has any tips on this they're very welcome.
    Thank you!
     
  12. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Glue a bit of 600 grit finishing paper on a flat surface (glass plate or a table saw top), mark the anti-dive unit with permanant marker, and slowly sand the unit flat. The marker ink will make any high spots evident as you work, and will need to be reapplied as you go.
    The same can be done to the fork lower, but shouldn't be necessary (you'll need a truly flat peice of steel to do that job; something thick).
     
  13. Polock

    Polock Well-Known Member

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    go back and get 12x3's and 3.5's
    i hate to say it but that means you broke them
    if the forks are all together maybe you can turn them upside down and not drain the oil
     

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