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  1. #1
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    Fox float fluid "pillow pack" in air chamber of RL?

    Just rebuilt by Fox Float 29 RL (80mm) - oil change and dust wipers. I see on the Fox site that you are supposed to remove the air spring assembly from the left side (looking at it from the top) and are supposed to put one of the pillow packs of Float Fluid in the top of the fork before reinstalling the air spring - what does that do exactly?

    Thanks
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  2. #2
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    It helps maintain the air seal. It's thicker than the suspension fluid used in the leg baths and damper.
    Float Fluid sits on top of the head of the air spring and helps to maintain the seal and prolong service life.
    Let the air out of the fork and remove the top cap and look inside the stanchion-you should see a bit of blue fluid sitting on top of the air spring.
    If you see no fluid, add the pillow pack.
    If you see green suspension fluid, drain it out and add the pillow pack.

  3. #3
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    ^^^Thanks Norman, that makes sense now. I will go ahead and pull off the air cap and look today.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

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  4. #4
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    some people use gearbox oil for that. it's not as thick but it gets the job done. and it's cheaper so you can use more, even for tuning the air chamber size if needed.

  5. #5
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    Holy cow! There was a bunch of green oil in there (now I know why there wasn't any in it when I drained the lower leg on that side!). I drained it out and added the blue Float Fluid pillow pack. Wow....now I have full travel again! I had noted that over the last few months....my fork seemed to not have as much travel as when new...I guess that was the reason. Does that happen normally (susp. fluid making it past the seal into the air chamber)?
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  6. #6
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    Yes, the bath oil migration in to the air chamber is a common thing with Fox Float forks.
    When it is severe it can mean that there is a failure of the scraper seal.
    However, if you stay on top of Fox's prescribed service intervals AND DO THE AIR SPRING SERVICE, you'll likely eliminate the problem providing you don't have a faulty seal.
    It's common for people to change bath oil and seals and skip the air spring service.
    It only takes a little bit of additional oil in the air chamber to drastically change the feel and limit the travel of the fork.
    By doing the air spring service regularly, you are managing oil migration before it becomes a noticeable problem.
    In your case, it doesn't automatically mean anything is wrong with your fork, it likely means you went too long in between service intervals.
    Just pay attention to the amount of travel and do another air spring check sooner than later. If you are seeing excessive bath oil in the chamber at the next service interval, you can change the seal(takes 5 minutes once the chamber is open). If it is only a little bit of green bath oil that has made in in to the chamber, just keep riding and staying on the service intervals.

  7. #7
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    Great info...a great example of why I like mtbr! What exactly is involved with the air spring service?
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  8. #8
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    If your fork is holding air pressure and oil migration is minimal between scheduled service intervals, then servicing the air spring is simple.
    You just did it by draining the excess bath fluid from the air chamber and topping up with Float Fluid.
    If oil migration is excessive between service intervals then you need to pull the air spring, replace a seal or two, top off the float fluid, and then you're good to go.
    Now that you've seen how quick and easy it is to pull the cap on the air chamber and check for fluid, you can inspect the air spring at any time.
    If you have a problem with the air spring it shows in two ways-loss of air pressure and/or excessive oil migration.
    Other than that, just keep it topped up with Float fluid and keep an eye on oil migration between service intervals.

  9. #9
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    I am a newbie here, but can tweaking the amount of oil in the chamber change the way the fork ramps up pressure under compression? I would assume more oil = faster ramp up because you are effectively reducing the volume of the air spring?

    thanks
    Shawn

  10. #10
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    Quote Originally Posted by Briareos View Post
    I am a newbie here, but can tweaking the amount of oil in the chamber change the way the fork ramps up pressure under compression? I would assume more oil = faster ramp up because you are effectively reducing the volume of the air spring?

    thanks
    Shawn


    I've been using light grease in the air chamber of my Nixon for years to reduce volume.
    lean forward

  11. #11
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    OP, common problem. Fox brought out a fix for it.

    If you read first few pages (and the rest if you have time) of this thread - Bath Oil Migrating to top of Air Piston

    On page 4 there are some pics of an air piston, that foam ring has to go which should stop the migration and if you can be bothered fox do a replacement which is a rubber seal. They should send it to you for free if you give them a call (or their service people depending which country you are in) The foam was holding fluid up near the seal causing it to migrate into the air chamber.

  12. #12
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    Quote Originally Posted by Norman Clydesdale View Post
    If your fork is holding air pressure and oil migration is minimal between scheduled service intervals, then servicing the air spring is simple.
    You just did it by draining the excess bath fluid from the air chamber and topping up with Float Fluid.
    If oil migration is excessive between service intervals then you need to pull the air spring, replace a seal or two, top off the float fluid, and then you're good to go.
    Now that you've seen how quick and easy it is to pull the cap on the air chamber and check for fluid, you can inspect the air spring at any time.
    If you have a problem with the air spring it shows in two ways-loss of air pressure and/or excessive oil migration.
    Other than that, just keep it topped up with Float fluid and keep an eye on oil migration between service intervals.
    Great, thanks! Air pressure loss is minimal-to-zero so I think I just waited WAY too long....14 months of hard riding too long!
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  13. #13
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    Quote Originally Posted by Briareos View Post
    I am a newbie here, but can tweaking the amount of oil in the chamber change the way the fork ramps up pressure under compression? I would assume more oil = faster ramp up because you are effectively reducing the volume of the air spring?

    thanks
    Shawn
    That was the effect it had on mine...I just couldn't get full travel b/c it ramped up too fast (before it could get to that last bit of travel).
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  14. #14
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    Quote Originally Posted by Briareos View Post
    I am a newbie here, but can tweaking the amount of oil in the chamber change the way the fork ramps up pressure under compression? I would assume more oil = faster ramp up because you are effectively reducing the volume of the air spring?

    thanks
    Shawn
    That's exactly how it works.

  15. #15
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    Such a timely thread with awesome advice! i am about to service my Fox OB RL 120 and was wondering about the air chamber, too. Thanks guys!

  16. #16
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    Quote Originally Posted by Reign2Rider View Post
    OP, common problem. Fox brought out a fix for it.

    If you read first few pages (and the rest if you have time) of this thread - Bath Oil Migrating to top of Air Piston

    On page 4 there are some pics of an air piston, that foam ring has to go which should stop the migration and if you can be bothered fox do a replacement which is a rubber seal. They should send it to you for free if you give them a call (or their service people depending which country you are in) The foam was holding fluid up near the seal causing it to migrate into the air chamber.
    TiGeo, definitely follow this advice. The other advice about "draining the excess oil off the air piston and putting 5ml of Float Fluid back on top of the air piston" is leaving out a very important factor: The excess oil on top of the piston is being "robbed" from the lower leg. If you don't replace that oil as well, you will won't have the proper level to lube the bushings and seals. Get the proper Fox parts to replace the foam ring on the air piston with the new seal and stop the problem from happening in the first place.

  17. #17
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    I got the new seal from Fox (free of course..they are so cool). Will replace at next service. Thanks for the info all.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  18. #18
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    Quote Originally Posted by TiGeo View Post
    I got the new seal from Fox (free of course..they are so cool). Will replace at next service. Thanks for the info all.
    You must be on the A-list--Fox told me it'd be $1.00 for the part and $8.00 shipping and that'd I'd be better off going to my LBS. Harumphhh!

    Anyone know which way the seal faces (I haven't seen one yet) if it's not symmetrical?

  19. #19
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    I guess I am A-list! My bike is a '12 so maybe it is a warranty thing. They sent me a top cap for the lock-out for free b/c mine wallowed out. They have been great so far.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  20. #20
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    Fox float fluid "pillow pack" in air chamber of RL?

    I've had good luck with removing the foam ring and keeping the existing scraper seal. I have not used Fox's new scraper seals.

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