F800GS Bitubo Fork Kit

Discussion in 'Parallel Universe' started by DockingPilot, Jun 1, 2009.

  1. The Griz

    The Griz Long timer

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    Not necessarily. Grease is too thick and would get pushed around and away from the parts that need lubrication over time, therefore effectively not providing enough lubrication for the spring against the inner wall of the fork tube at key intensive contact areas. Oil moves freely and continually provides lubrication indefinitely all over inside the fork tube. The fact is that fork oil in all motorcycle forks serves two main purposes:

    1)Damping - through variably sized orifices controlling the flow of fork oil. The larger the orifice, the more free the flow and the less damped the fork.

    2)Lubrication - of fork internals for longevity of parts.

    And correct me if I'm wrong here....but oil is slick isn't? In this setup it definitely doesn't go into the cartridges themselves. So using subtraction, it's easy to deduce that the oil's function would simply be lubrication in this application.
  2. bxr140

    bxr140 Flame Bait

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    Bit grouchy, then? :rofl

    As noted previously:

    1. Air spring. Probably the primary reason for fluid in the fork tubes with the Bitubo dampers. All suspension benefits from SOME amount of 'progressiveness', and this is achieved (in forks) by compressing the air above the oil. No oil would make the air spring virtually unnoticeable since you're compressing 30 or so inches of air into 20 or so inches of fully compressed fork. Too much oil (not enough air) makes the air pressure ramp up too quickly (say, 10" of air into 2" or so of space) and the forks become harsh. Proper tuning of oil height provides the optimal mix of compliance in the typically used range (give or take the first half of travel), but the necessary stiffness (and to a degree, resistance to bottoming) deeper in the stroke.

    2. Heat dissipation from the damper unit. Probably not the main reason for the oil, but certainly necessary, especially in heavy use. The sealed damper unit has far less fluid (and metal) than a conventional fork, but it does the same amount of work, and all that heat has to go somewhere. Overheated suspension fluid leads to accelerated wear on the hard parts, shortened life of the fluid, and less consistency with the damping.
  3. The Griz

    The Griz Long timer

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    I do agree with your air spring point. Fork oil height is important. I've sucked a few ml out of my stock forks to soften things up a bit. It helps!
  4. Bigem

    Bigem Long timer

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    I received an e-mail from the Australian importer of these kits today and he can supply one to my door for $860AUD. That's quite reasonable but I have decided that money would be better spent on a set of progressive fork springs and some oil weight experimentation for the F8 and a new pair of shocks, new fork seals and a new air filter and alloy bars for my vintage motocrosser!! :freaky:freaky:freaky
  5. Bruno T .

    Bruno T . N8YQ

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    Yes, i'm pretty sure it does.

    That's why the instructions clearly state that it is necessary to pump the damping rod to achieve proper oil leveling.

    And no, unlike you stated previously, the oil does not reside only above the cartridges. The majority of it actually resides below the springs.

    If you had installed a set on your 800 before spouting off like you know it all, you would know these things.
  6. The Griz

    The Griz Long timer

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    Actually, it was DockingPilot or bxr140 or someone who stated that the oil does not enter the cartridge. So, no, I'm not souting off like I know it all. I'm just going off of what you guys claim!!:lol3 Hmmm....interesting. I get shit on when I agree with you guys and when I disagree. Can't win!

    Thanks for the factual information about this kit though! I knew the oil had to be for something!
  7. bxr140

    bxr140 Flame Bait

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    Unless they've come up with some revolutionary technology, I find it hard to see how they can get the nitrogen charge in the damper unit before the fluid goes in there.

    I believe Docking Pilot when he says the units are sealed and you can't put oil in them. I believe him when he says the oil added goes into the fork tubes. Mostly because what he has said makes sense. :deal

    Without having read the instructions, or even hearing of this before you said it (did DP say anything about this?) I'd surmise the damper pumping is most likely becuase the units aren't shipped vertical. Makes less sense on a sealed, charged unit than a 'normal' fork, but who knows.

    What, exactly, do the instructions say?
  8. Bruno T .

    Bruno T . N8YQ

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    Go back and read Frank's comments. Unlike others, Frank doesn't make point blank affirmations, he is pretty candid regarding his knowledge.

    Frank isn't sure whether the oil enters the cartridges. Just as i'm not 100 % certain that it does.

    The only way for me to be 100 % certain is to remove one of mine and confirm that it is indeed filled.

    The instructions clearly state that the damping rod must be pumped in order to achieve proper oil leveling.

    The above, combined with the drop in oil level i observed when filling my forks (at the point where the oil reached the level where the rod enters the cartridge), the pronounced gurgling noises i heard, and the change in damping effort as i pumped the rod, leads me to believe that the oil does in fact enter the cartridge.
  9. Motoriley

    Motoriley Even my posing is virtual

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    Have you noticed the dreaded turbo-lag with the new set-up?
  10. Bruno T .

    Bruno T . N8YQ

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    Like this one for example, where you state that the forks on the 800 GS are "damper rods";

    You respond;

  11. The Griz

    The Griz Long timer

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    You're sittin' on a pretty high horse there, pal.

    The stock F800GS forks are indeed cartridge forks. It's just that they're the non-sealed type. As in the stock cartridges actually rely on the fork oil for operation. Also, the biggest problem with the F800GS stock forks is that the cartridge unit itself is crimped shut at the bottom, which hinders us from changing things inside the cartridge unit. This is not a blank assumption. This is fact. Touched and saw with my own eyes! Is that good enough for you?

    And about the Bitubo cartridges: If the manual states that the damping rod must be pumped in order to achieve proper oil leveling, then that seems to me to be a definite that oil does go into the cartridge unit. And I myself was never claiming anything on that subject for sure, only goin off of what I've been told by you guys.
  12. Bruno T .

    Bruno T . N8YQ

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    So you not only spout off at the mouth, but you also have trouble reading. Lovely.

    I know you're a young boy, but please try to follow along here.

    Where did i write that the 800 GS OEM forks are not cartridges ? Go back and read my post.

    I wrote;

    Since you're having trouble following along, i'll spell it out for you.

    You posed a question regarding the specifics on the F 800 GS suspension.

    bxr140 responded to your question matter-of-fact like.

    bxr140's matter-of-fact response was incorrect -- "Damper rods."

    The OEM forks are in fact cartridges, they are sealed cartridges.

    Get it ? Like i said, an example of someone making affirmations without knowledge.

    Here's another example;

    Non-sealed type huh ? Unlike all the other cartridges that ARE sealed and don't allow oil to flow through, right ?

    LOL.

    You should try talking about things you actually know about, you keep missing perfect opportunities to keep your mouth shut.
  13. The Griz

    The Griz Long timer

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    I didn't say you did. But now that you mention it, did you?






    The stock forks are not sealed cartridges. They are in fact unsealed cartridges. Oil is allowed into them. I know this because I touched and saw it! Do you get it yet?? Obviously not. Therefore you seem to be the one making affirmations without knowledge. My knowledge is from hands on experience with the stock forks.

    No where did I say that all other fork cartridge types are sealed. You made that up. But since you feel the need to bring the subject up again, some are sealed and don't allow oil into them, and others are unsealed and allow oil in. However, there are far fewer sealed cartridge fork systems than unsealed, due to the high cost of manufature and service difficulty. If you don't know that, then it seems you're the one that needs some schooling on the subject. Take some of your own medicine man!! For fuck's sake! For being a wise old fart :gerg, you are the one that seems to not be following along!

    Anyway, I'm going to go ride my motorbike across the country for 3,000 miles now.:ricky You can stay here and piss and moan about cartridges and how you can't seem to figure them out!!:lol3 Peace.

    http://www.sportrider.com/tech/146_9408_tech/index.html

    http://books.google.com/books?id=4MealMAQSeIC&pg=PA65&lpg=PA65&dq=sealed+cartridge+fork&source=bl&ots=15x9lOSwlz&sig=dyX3hkmdroyAvvwQUAOLtt_SPHc&hl=en&ei=21kxSr2MFpaOMseB5cMH&sa=X&oi=book_result&ct=result&resnum=1
  14. bxr140

    bxr140 Flame Bait

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    +1.

    btome, web fourms are supposed to be a place where different people present different ideas that other people can consider and, if they so chose, discuss. Instead of digging up old unrelated posts (specifically one that was immediately corrected, no less) and reading into them in an attempt to prove someone wrong, how about you just contribute?

    At least when Griz and I tussle we both try to actually further the discussion. :freaky
  15. Bruno T .

    Bruno T . N8YQ

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    I know this is a complicated subject for a young boy like you, but cartridges DO allow oil into them. That's how they dampen.

    The term "sealed" refers to Marzocchi having crimped the ends on these particular units.

    Depicted below, note the crimps preventing access to the interior of the cartridge;

    [​IMG]
    That's what the term "sealed" refers to.


    Really ? There is such a thing as a dual chamber fork ? You're kidding. Can you show me where they are referred to as "sealed cartridges" ?

    You post links to cartridge fork articles, you should study them.

    And the famous 3000 mile ride, don't you get tired of saying it over and over and over again ? "i'm going on a 3000 mile ride". Like the sold KLR's in your signature line, it's only a big deal in your mind. Get it ?
  16. The Griz

    The Griz Long timer

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    Just because the metal is crimped on the bottom doesn't mean it's sealed cartridge fork!! That's just to restrict access to it's internals from humans, not oil!:poser The term sealed in this subject matter means no oil allowed into the cartridge internal. You can plainly see the holes that allow oil into the cartridge in this picture.




    Oh, I'm sorry..... the term sealed isn't good enough for you.... Well, the term dual-chamber is synonomous with sealed-cartridge in this topic. And the point is whether or not the fork oil is allowed into the cartridge unit or not! Not what the effen thing is called!

    I have. Obviously you haven't. That's why I posted them for you.:thumb

    Now you're just blatantly trying to be an ass. Maybe if you went on trip you'd actually have something to be excited about, instead of being bored at work and trying to be a fuckwad to people. Jo Mamma time.
  17. Bruno T .

    Bruno T . N8YQ

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    Is that your lame excuse for stating something matter-of-fact that is incorrect ?

    You didn't present a "different idea", and you certainly didn't contribute anything by falsely stating that the F 800 GS has "damper rod forks".

    Why not just say "I'm not sure, but i think they might be damper rod forks" instead of "damper rod".

    It's ok to not know everything.

    As far as the high horse remark, other than a lame comment it really has no merit at all. I'm not the one that made false matter-of-fact statements - you are.
  18. Bruno T .

    Bruno T . N8YQ

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    What's the matter ? Can't stand getting called out on your spouting off ? Truth hurts doesn't it.

    BTW, bring back a nice picture from your "3000 mile ride" to share with us.

    Here's one of mine from Lake Atitlan, Guatemala. Taken this January.

    [​IMG]
  19. robhar54

    robhar54 Been here awhile

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    OK, Griz, btome and bxr140, enough already. This started out to be an informative thread on something lots of us are interested in, and has now turned into a dick-swinging contest. Take it to Jo Momma.:deal

    (Or at least that's what I'd say if I was a moderator. :1drink )

    Rob in Seattle
  20. Bruno T .

    Bruno T . N8YQ

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    Agreed.

    Ok, something informative.

    One of the spring preload screws came undone on the Bitubo cartridge. It happened when i was adding preload to the left fork, the screw simply untheaded from the hex shaft inside the cap.

    The screw (black anodized 12 point), is a left-hand thread and it turns a hex shaft inside the cap which in turn threads out a collar that adds spring preload.

    I was able to repair it by grabbing the collar (that pushes on the spring) with a pair of pliers and turning it counter-clockwise (add preload . .). I then cleaned the threads, re-lubed the washers (you'll see which ones) and locktited it back together.

    Pay close attention so as not to thread it in too tight, that's what causes it to be hard to turn.