Adventure 990 Fork Seal Job

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by 4Skins, Dec 26, 2012.

  1. 4Skins

    4Skins Johnny to most...

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    Installing new fork seals is a reasonably simple job to do at home requiring only basic tools and a few home-made special aids. The process can be a bit messy so I recommend you cover the floor with a sheet of cardboard and have plenty of old rag on hand. Here's how I did it.

    First of all you need to prop up the front of the machine and remove the front forks. If you need instructions for this then you probably shouldn't be undertaking the rest of this process!

    Before you loosen off the tripple clamps to remove the forks it's a good idea to loosen off the top caps. Strictly speaking this should be done using the special tool with the knobby bits that fit onto the holes around the fork cap. But as I didn't have one, I just backed off the big preload nuts (24mm?) on the fork cap till they bottom out then eventually they will start the cap unscrewing - Hint: Count the number of turns till they bottom out. I'll probably get flamed for this, but hey, it works and I didn't have to go begging to borrow special tools!


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    After you get the cap undone all the way tip out all the oil onto a CLEAN catch tray (2 litre plastic icecream tub).

    Then here comes the brainy bit... We use one of the basic rules of physics - you can't compress a liquid - to press the old seal out of the leg without dismantling or damaging the fork assembly.

    Now open up the cap on the other fork and tip the oil from the first fork onto it. Pour in as much as you can then screw the cap back on (it doesn't need to be real tight).

    Now lift the dust seal using a thin wide screwdriver and slide it all the way to the bottom. Remove the main seal retainer clip using a pair of small screwdrivers and clean all the crap out from the area.


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    Remove the #2 Philips head csk screw from the fork cap and compress the fork and expell all the air.


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    Replace the bleed screw while there is oil coming out of it. There will now be no air in the fork at all.


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    Now it's tilme to get out the carpentry tools and make up a jig as shown to hold the fork. I could have given you dimensions but I forgot to measure it. I just built it, used it then dismantled it. Hint: don't drive the nails home till you know the positions of the blocks are right.


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    The 4" x 2" lever bar needs to be at least 4 or 5 feet long to make it easy for you. When you get it all lined up with the lever pressing at right angles to the fork leg, apply pressure and the seal just pops out. Piece of cake!


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    Catch the spillage with a rag and try not to loose too much oil as we need it to repeat the process on the other leg.



    Click here for a YouTube clip of the seal popping out



    It's time to dismantle the fork to replace the seals. You'll need a thin 22mm open ender. I actually used the grinder to open out a shitty old 19mm I had and that did the trick.



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    You need to partially compress the spring to fit the 22mm in. Once you have the spanner in place you can use a 24mm ring spanner or socket to remove the fork cap and spring. Keep the parts clean for reassembly.


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    Using your fingernails, remove the Teflon coated piston ring from the fork staunchion

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    And put it somewhere clean and safe

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    Remove the washer


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    and slide the old seal off


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    Clean out any dirt and crap and make sure none goes down the fork.


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    Now carefully install the new seal (taking care that it is the correct orientation) by sliding it carefully over the piston ring groove so as not to damage it.


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    Now reassemble the fork in the reverse order to dis-assembly.


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    Push the new seal in as far as you can by hand... Note the aluminium soft jaws on the vice!


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    Then carefully and gradually tap it in till it hits home and the circlip groove is fully visible around its circumference. Have somebody turn the other end of the fork gradually for you as you tap away.

    Once again I'll probably get flamed for this but if you take your time and take care to keep the screwdriver well clear of the seal surface it'll all work out. It'll tollerate a bit of damage around the outer edge without affecting it's performance. Call me rough but but hey, it works and I didn't have to go begging to borrow special tools!


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    Reinstall the retaining circlip. If it doesn't snap in all the way around, you didn't drive the seal home fully.


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    All you need to do now is refit the dust seal and refill the oil. See this Youtube clip for the oil refilling procedure

    I used 7.5 weight fork oil filled to 100mm from the top. A steel ruler does the trick for measuring the level, no need for the elabourate sucker tool.


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    Don't forget to properly tighten the fork caps after you have reinstalled the forks in the tripple clamps. Then reset the preload adjusters (standard is 5 turns).

    That's it, no more oil puddles on the garage floor.

    Cheers, 4 Skins
    #1
  2. bikemoto

    bikemoto Tyre critic

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    4skins photo essay :D Spotted your youtube vid the other day. I'm about to do this job for the nth time, so keen to see if there are easier ways!
    #2
  3. 4Skins

    4Skins Johnny to most...

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    All finished now Colin. This procedure is a lot easier on conventional forks where you can slip the seal straight off the end eh. Nice to hear from you mate.
    #3
  4. Vicks

    Vicks gets stuck in sand

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    I cringed when i saw the screwdriver being used to drive the new seal in !!!

    You know you could have cut a portion of the old seal and used it to do the same job. much more peacefully (for other inmates atleast).

    edit : i won't even go into the other concerns i found...
    #4
  5. Zuber

    Zuber Zoob

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    Quick Kids, How many major mistakes did you spot? Here's the ones that I saw...

    1. Never try to remove the fork cap without loosening the upper triple clamp or you'll never it off.
    2. Don't use the big hex nut to loosen the cap, you can jam it and trash the cap. $85 each vs. $35 for the pin tool.
    3. You don't need to use hydraulic force to pop the seal out.
    4. if you do use this method, pull the black plastic adjuster cap off the top so you won't crush it. $20
    5. Don't use the red seals from anyone, use only the black NOK or green SK seals.
    6. Never push a new seal over the sharp edge of the fork tube, use a plastic bag and thin grease to protect it. $do it again$
    7. Never clamp the steel tube in a vise, never, ever. $485
    8. Never hammer on a seal with a sharp steel tool, never next to the steel tube. $485 or next to the aluminum upper tube $LOT$ Just use a pvc pipe and a hose clamp.
    9. Don't hammer on the dust cap, you can just push it on with your hands with a little grease on it.
    10. Use 5wt fork oil. 7.5wt is too stiff.

    I do salute your ingenuity though. I've had to do jobs like this far, far away from assistance and special tools. I hope you fixed it.
    #5
  6. 666

    666 Agnostic and Orange

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    +1.
    #3 is done easily by heating fork with a heat gun(as per manual)
    Number 7 is pretty crazy. I almost cried looking at it.
    Special tool for #8 is just 30$, works for all ktms.
    #6
  7. charlie264

    charlie264 Long timer

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    I was going to say, stay away from the forks...electrical tape around the lips when putting seals on.

    Loob everything with fork oil, I don’t know why these vids and tutorials say use grease on the stations. Think butter on toast, just attracts and holds shit.
    #7
  8. Peanuts

    Peanuts Long timer

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    Poor bloke. You will be having a go at him for no cross bracing on his timber bike stand next ;)
    #8
  9. Brokein2

    Brokein2 Been here awhile

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    Hey......Leave this poor guy and his methods alone.......My wife sells KTM parts for a living and this will help her sell more. :clap
    #9
  10. Johnf3

    Johnf3 Long timer

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    All I know is that I would have used SKF seals and wipers. I have not had any leak and they have no stiction.

    If you do lots of suspension, you see the tell tale signs of hammering fork seals in with a screw driver all the time--vertical nicks and gouges in the tubes right where the seal seats. Not to mention internal damage to the cartridges, damper rods from vices and other ham- fisted methods.

    The OP took lots of good pictures to document the procedure--right tools and methods or not.
    #10
  11. fast4d

    fast4d Long timer

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    yeah I'm guilty of that too. I loosen the top triple first though.

    cap is sealed with o-ring so I only tighten 'hand tight'

    as for seal driver it's so much easier with the proper tool. I used cut up sections of PVC pipes. PITA to do but my seals usually last 30k+ so I don't have to do too often.
    #11
  12. ColoradoBigfoot

    ColoradoBigfoot Been here awhile

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    Very detailed report. Thanks. It was very helpful since I recently noticed some oil on left fork tube. Not really a leak per say (yet?), just can see a line of oil where compression stops. No seepage overnight.
    This post and the ensuing comments have pursueded me to just take my bike to the shop, cost and inconvienience be damned.:1drink
    #12
  13. DirtyADV

    DirtyADV Long timer

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    Place a plastic bag over the end cause 2 small steel balls will fly all across the workshop when undoing the plastic adjuster cap.

    Since I think ill have to do this multiple times on a bike I prefer to get some of the special tools but it good to know how to do a "bush" fix.

    My fork seal change.

    /Johan
    #13
  14. laramie LC4

    laramie LC4 crash test dummy!

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    thank you. i was worried i was gonna have to type all that.

    in the future, clear packing tape wrapped around the top of the fork makes it easy and safe to install new seal without cutting them. use it every time i do a change.

    like the "can do" attitude, just may want to do a little more research first. but then again, that's how we learn, by fucking up the first time.

    laramie :beer
    #14
  15. Hipster

    Hipster Long timer

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    I like Zuber's plastic bag for protecting the seal during installation, I'll have to try it next time.
    #15
  16. amanlikemike

    amanlikemike Recovering Speedfreak

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    We may not agree on how to do it...

    But I'm fairly sure we'd all like to do it less: :wink:

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    Jus' sayin'! :thumb
    #16
  17. beergut

    beergut Thumper

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    I just rebuilt my forks last weekend, and used the tutorial on the HOW. I used Slavens vid on how to fill the oil level and set it to 120mm using 10wt oil. *by the way, fork oil weight and oil level info/discussion seems to be absent from the all mighty interweb. :cry

    The front end seems great after the rebuild. SKF seals/wipers were used.

    Regarding the heating of the tube...once you get the snap ring out, the tubes pull apart. I slid them back and forth a bit and they came right apart.

    Also, I didn't use some crazy contraption like posted. A bucket, some rags and brake cleaner did the trick. I did spend the money on the motion pro cap tool, the seal seat tool and the cap protector thing. Everything ordered on Amazon was $68 delivered. Having these tools made the job a breeze.
    #17
  18. Zuber

    Zuber Zoob

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    Some times, you need to heat the tubes. You can beat them apart, but you may ruin the bushings. If the seal doesn't come right out, a little heat helps.

    BUT, before you go replacing the seals try cleaning them. If the bike doesn't have many miles on it, you may only have some dirt holding the seal edges away from the tubes. This thing works>
    http://www.riskracing.com/pages/Seal_Doctor_Page.html#.UXYdDMr84qM
    #18