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  1. #1
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    Fox DHX5 Air Bleed

    Howdy folks. I bought a DHX5 that had a lot of air in the damping circuit so decided to dive in and sort it out. I came across some good info online that other folk had put up though much of it was for the coil version, and the air appears a little different in that it's inverted by comparison and thus slightly more involved because of an additional shaft volume and orientation issue. I'd read beforehand about the possibility of submerging the entire unit in oil to do this but I didn't have this much oil around, and also didn't really want to have to do it that way, so I came up with the following...

    Whether there be better ways to do this I don't know (in hindsight there are likely a number of possible methods), but can say that the following worked well for me and required very little oil and only basic tools to complete. So, for what it's worth, here are a bunch of images and short descriptions of what I did;

    * You can click any image for the full resolution version *

    The first 4 images just show the hardware I started with prior to getting the process rolling. I'd removed some parts for cleaning and so are not shown here. Aside from the main air piston seals I'd also removed an o-ring from the bottom out adjuster to make things a little easier further on (not essential).







    To use only minimal oil to complete the procedure I used an empty pill bottle with bottom cut off and fitted some draft strip foam to allow for it to slide/seal onto the main shaft;



    Clamping the assembly upright using my truly amazing vice + plastic chair. Nothing but the highest tech here...



    1. Greasing an o-ring in preparation.

    2. With the floating piston removed from the piggyback I introduce as much new oil into the system as I can at this point. This is mainly to effectively flood the whole piggyback & oil ways to help with bleeding later on.




    With valve core removed I hand tighten the bottom-out assembly into the piggyback. Once done I continue to pour oil into and onto the damping piston side so that both sides are about as full with oil as can be and then close the piggyback side with a dust cap.



    On the main piston shaft near the eyelet there's a very handy screw that's hidden under a little white plug. Pop that white plug off to reveal a 4mm grub screw. Unscrew that and there's a little rubber bung that seals it off underneath. Pop that out to effectively open up the shaft volume for bleeding later on.

    Now gently slide the shaft onto the oil piston/air piston, screw it up tight, then push the shaft down into its stroke (slowly to minimise foaming the air/oil inside).



    Pop on ghetto oil reservoir and add oil. Not much oil was needed, maybe only 50cc or so here. At this point it's a pretty simple process of sliding the shaft up/down to gradually exchange oil for air in the system.

    I spent about an hour at this stage pulling (pushing) air out, including leaving it to settle here and there. It's very much like bleeding hydraulic brakes and is easy to get an idea of how well things are going by just listening for the obvious sound of air bubbles shifting about, and observing bubbles ejected into the oil reservoir. After a while when things were feeling nice I dialed in a load of rebound to add resistance to pulling the shaft back up its stroke. This seemed to operate similar to pulling on a syringe when doing hydraulic brakes in that (I guess) it causes any tiny air bubbles in the oil to expand and float up faster towards the top of the shaft, and thus into the reservoir. I also tilted the assembly about and gave it a tap/knock here and there to help loosen any bubbles trapped in the system. Doing all this got it to a point where I was confident it was well degassed.




    1. Here I extended the shaft fully, tilted the assembly back, slid the reservoir down to give access to the grub screw, then carefully popped the rubber bung in the hole without introducing any air (easy enough) and screw the grub screw back on to seal it up.

    Now the whole lot is sealed tight and so you should have a very strong hydraulic lock assuming most of the air is out. I could barely compress the shaft ~1mm at this point.

    2. Here I remove the bottom-out adjuster to access the piggyback again. There were actually some small bubbles stuck to some surfaces in the piggyback base so I prodded those loose with a zip tie. In hindsight it might be worth gently pushing the shaft into its stroke a small amount at this point to push any potentially trapped air bubbles around the ProPedal valve section into the piggyback volume, making sure to return the shaft to full extension prior to reinstallation of the IFP.




    1. Ready to reintroduce the IFP.

    2. With the centre screw removed I pop the IFP back in.




    1. Here I set the IFP depth to 33mm for this 190x50mm (2 inch) stroke shock unit (based on info gleened off teh intertubes ), re-add the centre screw to seal it up, drain the excess oil, and added some 85w gear oil for happy days.

    I'd be careful not to cycle the main shaft at this point, or at least only very gently if doing so as the piston looked to wiggle up/down unevenly (with potential to break seal) without the usual "75-200psi" pressure backing it (I presume pressure would normally keep this in check ).

    2. Reassembling bottom-out to piggyback and repressurising.




    Viola! It's at this point I can cycle the shaft pretty hard and check to see if it at least feels alright. Good news is it felt bang on. There was no sound of air in the system at all and it all felt very slick. I'm pretty confident the procedure has worked well at this point, and so just the nice easy air can reassembly to do now.




    I can confirm all feels well after completing everything and installing it on the bike. In comparison to what the unit was like beforehand it's a lot better. It's virtually silent in operation now when bouncing on the bike. So damn good. I'm just glad it was all a relatively painless process that even a n00b like me could pull off with only minimal tools and experience.

    Hope someone finds the info useful.
    Last edited by EmanResu; 06-16-2016 at 03:41 PM. Reason: Fix broken image links for new forum

  2. #2
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    Looks like here is another bleed port at the other end as well. You can see it in this cut away pic: http://www.cyclingnews.com/tech.php?...HX_Air_cutaway

    IIRC one the guys on RM (Udi maybe) used a hollow bolt from the bottom of a boxxer to thread into the bleed hole you used. He then attached a syringe with a hose to the bolt to pump oil back and forth, working the oil out.

  3. #3
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    Nice image. I did come across that screw before starting the bleed above as I depressurised both chambers and then, out of curiosity, unscrewed that Allen head to try to determine what it was as I couldn't find info on it anywhere. What happened then was it blew a shitload of oil out under pressure into my face and halfway around the room. It wasn't the wisest of moves... and pretty much ruled out me being able to measure IFP depth before I started the bleed.

    I know there are probably a good number of ways to bleed these now, as you mention, using any combination of the 3 points in the system. My options were a bit limited really as I didn't have anything capable to syringe in that way, and tbh really wanted to break the unit down anyway to flush/clean it out properly, so it worked out OK for me. Anyone not wanting to go to such lengths could indeed simplify the process no doubt.

  4. #4
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    Two big 'ol thumbs up to you for getting into the shock and fixing it yourself. I am always dumbfounded at how little tech info is available from bike component mfg. and that is 10 fold when you start talking about suspension.

    Just trying to add some more info to your great thread.

  5. #5
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    Thanks, really appreciate the comment. I know very little myself but have found the bits of info folks post online including images have helped me a lot before venturing into stuff like this, so I'm just trying to offer a bit in return (even though it may not be the best advice I give).

    I don't like how some manufacturers appear to restrict service information from the public and a part of me posting such is indeed a small act of retaliation in that regard. So if what's posted can help someone like me get in there and fettle things on their own back and probably learn a lot from the experience, then that's cool. [/seriousness]

  6. #6
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    This is a brilliant write up! Ask a mod to sticky this into the suspension maintence thread, it should be!!

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    Nice work.

    Adding the link To Udi's how to.

    http://www.ridemonkey.com/forums/sho...d.php?t=201454

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    Cheers Nick_M2R / Furrner.

    Had a root about for some IFP depth values and came up with the following numbers;

    Code:
    Metric ;
    190mm, 50mm = 32mm
    200mm, 50mm = 32mm
    200mm, 57mm = 33mm
    215mm, 64mm = 34mm
    222mm, 64mm = 34mm
    241mm, 76mm = 38mm
    
    Imperial ;
    7.500, 2.00 = 1.25
    7.875, 2.00 = 1.25
    7.875, 2.25 = 1.30
    8.500, 2.50 = 1.35
    8.750, 2.50 = 1.35
    9.500, 3.00 = 1.48
    The metric values are rounded slightly to convert from imperial but are very close. They may be different for coil versions, I don't know. * Don't quote me on them.*

  9. #9
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    EmanResu you save a lot of money and time for me! Good jub!

    I rebuild my shock today and he's working much much better.

    But, i have a one question that don't give me to sleep well. in regular air sleeve maintenance i'm relieves both pressure valves, because it's much more easy to put air sleeve back. I thus do not change IFP depth?

  10. #10
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    Quote Originally Posted by GR_Russia
    EmanResu you save a lot of money and time for me! Good jub!

    I rebuild my shock today and he's working much much better.

    But, i have a one question that don't give me to sleep well. in regular air sleeve maintenance i'm relieves both pressure valves, because it's much more easy to put air sleeve back. I thus do not change IFP depth?
    I'm not too sure what you mean exactly so forgive me if I read you wrong. I think that if all you have done is service the airsleeve then <i>no</i>, you shouldn't have to recalibrate the IFP depth (I did this also as it made it a lot easier ).

    If afterwards though you then found a lot of air in the damping circuit then it could be possible (small chance maybe) that air managed to pass the IFP seal and into the damping oil as I *think* (i really don't know if true) that usually the IFP would need pressure acting on it in order to keep it properly stable (and thus sealed) as it slides up & down the piggyback when cycling the shock unit (aggressively). This might be a reason why it's stated that it should never be ridden without minimum air pressure in the piggyback (just a theory). I think it should be fine though when just using minimal pressure to help with screwing the airsleeve back on.

  11. #11
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    Quote Originally Posted by Nick_M2R
    This is a brilliant write up! Ask a mod to sticky this into the suspension maintence thread, it should be!!
    I added this thread to the Fork and Shock Service Information sticky thread.

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    Quote Originally Posted by EmanResu
    I'm not too sure what you mean exactly so forgive me if I read you wrong. I think that if all you have done is service the airsleeve then <i>no</i>, you shouldn't have to recalibrate the IFP depth (I did this also as it made it a lot easier ).

    If afterwards though you then found a lot of air in the damping circuit then it could be possible (small chance maybe) that air managed to pass the IFP seal and into the damping oil as I *think* (i really don't know if true) that usually the IFP would need pressure acting on it in order to keep it properly stable (and thus sealed) as it slides up & down the piggyback when cycling the shock unit (aggressively). This might be a reason why it's stated that it should never be ridden without minimum air pressure in the piggyback (just a theory). I think it should be fine though when just using minimal pressure to help with screwing the airsleeve back on.
    You understood me right, yep. Simply, when I unscrew bottom out i has found IFP displaced. The depth of IFP was only 12mm. It became food for such thoughts

  13. #13
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    Quote Originally Posted by GR_Russia
    You understood me right, yep. Simply, when I unscrew bottom out i has found IFP displaced. The depth of IFP was only 12mm. It became food for such thoughts
    12mm doesn't sound right at all. Are you sure that the shock was extended fully before you measured? If it wasn't resting at full extension and was instead pressed into its stroke then the IFP would measure short like that. If you can feel a lot of air in the damping circuit then maybe air passed the IFP seal, but really I would have thought that might be hard to achieve unless it was rode without sufficient pressure in the piggyback. If the damping circuit doesn't feel/sound like it has air in it then I can only imagine that either the unit was pressed into its stroke when you measured, or you have too much oil in the damping circuit and still need to set IFP depth (did you actually bleed the damping circuit here or have you only serviced the airsleeve?).

    I'm noooo expert but I'll try to help if I can.

    ---

    @All Mountain : nice one

  14. #14
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    Well, i think when i unscrew the bottom out in process i compress the shock and it could be the main reason why IFP wasn't on the place.

    Anyway i completely change oil in my shock with correct IFP depth

    P.S. EmanResu can i use your illustrations pics for Russian forum? I will put your copyright on them

  15. #15
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    EmanResu, you rock!

    Great write up!

    P

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    Quote Originally Posted by GR_Russia
    Well, i think when i unscrew the bottom out in process i compress the shock and it could be the main reason why IFP wasn't on the place.

    Anyway i completely change oil in my shock with correct IFP depth

    P.S. EmanResu can i use your illustrations pics for Russian forum? I will put your copyright on them
    Good to hear you got it sorted. I think if the airsleeve was installed prior to measurement of IFP depth then it would be essential to have the main air chamber pressurised in order to keep the negative air spring from sucking the shock down in its travel. I don't know if you did it with or without the airsleeve installed, but either way it's important to keep the shock extended fully to ensure the IFP rests at its maximum depth before measuring it.

    And please go right ahead and use the images for whatever you want if you can find use for them. I don't care for copyrights on them. Cheers.

  17. #17
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    What about the Nitro re-charge?

    Hi,

    Just reading through your tutorial, as I'm about to embark on a DXH Air service myself. I admit, I'm a noob as well when it comes to Fox suspension.

    I spoke with a buddy at the LBS & he gave me the "trust me, you don't want to go there" warning when I asked about doing a full service. He handed me the air sleeve service kit with a smile & recommended I stop there.

    Apparently, the dampening chamber is charged with nitrogen at ~300psi & the only way to get it properly put back together with the nitro re-charge is to send it to Fox (or sim. operation).

    Can anyone with some experience shed some light on this?

    Thanks

  18. #18
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    Quote Originally Posted by drewachabal
    Apparently, the dampening chamber is charged with nitrogen at ~300psi & the only way to get it properly put back together with the nitro re-charge is to send it to Fox (or sim. operation).
    There is no nitrogen in the DHX Air. Your buddy is referring to the "inline" shocks which do have nitrogen or the older RC models.

    Where you add "boost" air is where the nitrogen would be on your shock. But they gave an air valve to add air

    P

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    Thanks P!

    I guess it's full steam ahead.

    One more question - what type / viscosity of oil is recommended?

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    Hey there. As Mr. P mentioned there is no nitrogen charge in there, only oil and air. As far as the difficulty level, imo it's a pretty simple, straight-forward task - not complicated at all - though I'd just be careful as you're working on it to avoid inadvertently damaging anything.

    Re: Oils; I used 'Castrol Synthetic Fork Oil' 5w when I did the above, though I did it again just recently but with 10w this time. I think the more precise measure of the viscosities I used are as below (data pulled from http://www.peterverdonedesigns.com/);

    Code:
    Fox 7wt Oil (Torco RSF Medium)
      cSt@40	31.82
    Castrol  5wt Synthetic Fork Oil
      cSt@40	28.00
    Castrol 10wt Synthetic Fork Oil
      cSt@40	42.00
    The original Fox oil is (as far as I know) the Torco RSF Medium there listed as 7w, so of the 2 oils I've used so far both fall either side of that weight-wise. I don't imagine this causes any particularly negative side effects, just minor differences in damping and propedal values (e.g. running 8 clicks rebound on 5w oil might equate to only 5 clicks on 10w). I guess I could have just mixed the two weights to produce an equivalant ~7w but haven't seen a need to really (I was also interested to see what differences there were in how they operate).
    Last edited by EmanResu; 04-30-2009 at 09:07 AM.

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    Alright! Total success with my re-build. Thanks to EmanResu for the great pics & instructions.

    A couple tweaks from his method that may help others:

    1. The small panhead allen screw near the rebound adjuster is a great way to relieve the pressure in the dampening side while containing/controling the inevitable spray of oil. I just shot it into a rag.

    2. I didn't have a spare pill bottle handy to rig up the oil feeding into the dampener, so I stretched a piece of road tube around the end of the dampening piston & a syringe from a Juicy brake bleed kit. Worked great.

    I tried to set up a brake bleed scenario to really pull the air bubbles out of the oil - one on the end of the dampening piston & one on the end of the boost chamber - but there wasn't enough air volume available in the Avid syringes to do so. If you can find some high volume syringes, you're golden.

    Anyways, it was not hard at all & the replacement seals kit from Fox was only $10 at my LBS.

  22. #22
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    Quote Originally Posted by EmanResu
    Cheers Nick_M2R / Furrner.

    Had a root about for some IFP depth values and came up with the following numbers;

    Code:
    Metric ;
    190mm, 50mm = 32mm
    200mm, 50mm = 32mm
    200mm, 57mm = 33mm
    215mm, 64mm = 34mm
    222mm, 64mm = 34mm
    241mm, 76mm = 38mm
    
    Imperial ;
    7.500, 2.00 = 1.25
    7.875, 2.00 = 1.25
    7.875, 2.25 = 1.30
    8.500, 2.50 = 1.35
    8.750, 2.50 = 1.35
    9.500, 3.00 = 1.48
    The metric values are rounded slightly to convert from imperial but are very close. They may be different for coil versions, I don't know. * Don't quote me on them.*

    Booya - that's what I was looking for!!
    Great post and thanks for the info

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    Quote Originally Posted by drewachabal
    I didn't have a spare pill bottle handy to rig up the oil feeding into the dampener, so I stretched a piece of road tube around the end of the dampening piston & a syringe from a Juicy brake bleed kit. Worked great.
    I like that idea, I'm guessing you could even expand on that and have one on the Boost (IFP) chamber too which I think should allow you to cycle oil through the whole system (EDIT: Ignore me, I realise now that's exactly what you said in the following paragraph *doh*).

    Many possibilities … and good to see folks experimenting with their own (as I certainly don't think mine the best, merely sufficient).
    Last edited by EmanResu; 05-19-2009 at 01:21 AM.

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    Cheers for the info. My shock has been making some air noise for a while now, I must have cycled it with no pressure in the boost valve (you'd think they'd just put 2 o-rings on the IFP which would solve the problem of going off-camber inside the piggy and letting air in). Refilled it with some 10wt Motul Factory Line which is a bit thicker than factory but not by much.

    I went totally ghetto and did it without a vice - all by hand which made it a little tricky but still achievable. I also just used the air sleeve as an oil reservoir over the top of the damper shaft which worked fine - only problem being that there wasn't much space to get the plug back into the bleed port, but a pair of very long tweezers worked.

    There is still a little air in there but much less than what it had - i'll cycle it again after a few trail runs. I'm happy as well 'cos i know now that the IFP is at the right depth.

    Also had a look at the shim stack and rebound port when i was in there. Looks easy enough to change the shims but you have to fill and bleed each time - a little messy.

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    Quote Originally Posted by DJR_9000
    (you'd think they'd just put 2 o-rings on the IFP which would solve the problem of going off-camber inside the piggy and letting air in)
    I've wondered about that o-ring too. To me it looks as though the IFP was originally designed to house a 'quad seal' like the main piston as that o-ring just doesn't seem to fit right. I was considering throwing 2 rings in there also for this reason.

    Quote Originally Posted by DJR_9000
    Refilled it with some 10wt Motul Factory Line which is a bit thicker than factory but not by much.
    I made a mistake above I think if you're basing your thoughts on the 7wt mentioned being standard. As I understand it now I believe 10w is the new default for the DHX though I don't know what brand so am unaware of a viscosity value to aim for. No big deal either way I don't think, I've run a 5w and 10w a bit now and can't say I've noticed any huge difference between them.

    Quote Originally Posted by DJR_9000
    I also just used the air sleeve as an oil reservoir over the top of the damper shaft which worked fine
    This is genius, can't believe I never thought of that! I'll definately be nicking this idea next time I do mine.

  26. #26
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    Well i just did it to my 08 DHX Air, worked like a bloody charm, thanks Eman!

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    Good stuff. Done mine a few times now and it's worked reet enough. I even gone and bought a nice big 6" jaw vice for the workshop which is a beautiful thing.

    If I may just add a note about the Fox brand "10wt" oil, I believe it may actually be rebranded Silkolene Pro RSF 10wt with a cSt@40 of 47.36 from what I was reading, so there's a figure to aim for. Not sure I'd use an oil that thick myself now having tried 42.00 and 28.00 as I'm thinking I preferred the 28.00, but each to their own.

  28. #28
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    I used castrol 10wt fork oil, the shock feels so nice now

  29. #29
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    Great Post,
    Very helpful

    Ride On!

  30. #30
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    Took a crack at mine, found some nice rebound and compression(20x10x.1, 18x10x.1) shim stacks. I thought someone had mentioned the DHX had no shims but I cant remember the thread...have a go at the tuning





    With fresh oil and a bleed it feels really firm and tight. I used a latex glove instead of a pill bottle. Cut a finger tip off and stretched it over the shaft, zip tied and was off!
    Last edited by thebronze; 02-18-2010 at 05:15 PM.

  31. #31
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    Quote Originally Posted by thebronze
    Took a crack at mine, found some nice rebound and compression(20x10x.1, 18x10x.1) shim stacks. I thought someone had mentioned the DHX had no shims but I cant remember the thread...have a go at the tuning

    With fresh oil and a bleed it feels really firm and tight. I used a latex glove instead of a pill bottle. Cut a finger tip off and stretched it over the shaft, zip tied and was off!
    Bronze... please let us know if you get to get rid of the wallowy mid-travel with your tuning.
    Check my Site

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    Well if it ever stops snowing in Texas then i'll thrash it and let ya know. I can tell you it feels way stiffer on the curb checks. Then again i'ts also got fresh oil and a proper bleed so it should. I'll keep you posted but its worth saying this shock is incredibly easy to work on. It was easier to open up the shims on the dhx than any of the forks i've valved. I've been watching ebay for an RP2 but this might pacify me at least for a little while.

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    Thanks for posting the guide EmanResu, however, I'm struggling to get a good bleed. When I've finished and I compress the main shaft it's springing back - which suggests that there is still a load of air in there yes? I know the guide said you spent an hour or so pulling the air out but after a few cycles I don't seem to get any more bubbles despite tapping and tilting. Am I just being impatient? Any more tips appreciated.

    Cheers

    Matt

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    So I was able to get about 12 miles yesterday on the dhx. I noticed right away that the propedal adjustments made a difference I could feel. I ended up with about 130psi in the boost, 190 in the main after trying some different things and it does indeed feel firmer in the mid stroke. I'm not sure thats due to the shims since I also reset the IFP depth, bled it, and changed the oil.

    It would have been nice to have only bled and reset the IFP but taking the fork apart is kind of a chore and oil is $$.

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    Hi all,

    I'm beginning this process on my DHX Air. However, I can't get the top of the piggyback off! Is it reverse thread? I removed the valve core, and released pressure by removing the 4mm bleed plug.

    Any tricks? I have it in a vice and crankled on it, but I felt if I went any harder I might break something!

    Thanks in advance!

  36. #36
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    Quote Originally Posted by jay80424
    Hi all,

    I'm beginning this process on my DHX Air. However, I can't get the top of the piggyback off! Is it reverse thread? I removed the valve core, and released pressure by removing the 4mm bleed plug.

    Any tricks? I have it in a vice and crankled on it, but I felt if I went any harder I might break something!

    Thanks in advance!
    Try using a propane torch to gently (and I DO MEAN GENTLY) heat the area till its hot to touch, then try again, They can be quite tight sometimes, just keep trying, my DHX C's was a mofo to get off the first time

  37. #37
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    OK, Got it. I think it was dry. I loaded it with some shock oil, and let it sit for a few minutes. Came out no prob.

    I couldn't get the air sleeve shaft off the main oil shaft, so I skipped that step.

    I didn't have a pill bottle around, so I just inverted the air sleeve on the shaft, and filled it with BelRay 5W shock oil, cycled it for a while, and now i'll let it sit overnight to let any little air bubbles get out.

    Thanks for this great giude. This isn't as "impossible" as Fox made it out to be.
    Last edited by jay80424; 03-31-2010 at 08:54 PM.

  38. #38
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    Pry the rubber stopper out. I used the flange to set mine. This article rocks.

  39. #39
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    Yeah it does, I love the dhx air now. I can tell you putting that extra shim really changed this shock. It no longer squats on climbs and feels a lot firmer then before. In fact its a bit too firm, even w 100 psi in the boost. I think next time around I'll switch it to a 16mm for #3. Mid travel has definitely firmed up and I havent used all the travel since the mod, getting about 90% but havent hit any big drops.
    Currently on
    20x10
    18x10
    18x10

  40. #40
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    Hey Guys, when setting the IFP depth, do you measure to the center of the IFP (where the screw goes), ot out on the side? As measuring to the center would put the IFP lower at the same depth.

    Thanks

  41. #41
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    (sorry it's been a while, I don't come through here too often ... )

    @jay80424 - Measure from the flat of the IFP, not the raised centre screw.

    @dirtmatt - When you mention you had "finished", if by finished you meant you had completed reinstallation of the IFP and bottom out adjuster (and maybe also repressurised the piggyback), albeit still had the airsleeve to do (as in the last pic), then at this stage it should indeed spring back after compressing the shaft as it will be compressing the air in the IFP chamber as the stroke causes the IFP to move up the piggyback, which then acts as a spring. This would be normal for this stage.

    If on the otherhand you had not yet reinstalled the IFP (set it to depth & closed the centre screw), as in you are at the stage where the entire piggyback is still full of oil, then you shouldn't be able to compress the main shaft at all if there's no air in there.

  42. #42
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    Hi, I have a 2006 Spec Enduro with that "special" DHX5Air, with sealed IFP chamber. Rebound and ProPedal are non existent, even fully closed. What are my chances to self-service that shox? I heard that I can't bleed it by myself due to that special IFP.

    I'm in Spain and there is no official Fox service right now... pse help!!!

    Thanks!

  43. #43
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    Quote Originally Posted by Booty-farrah
    Hi, I have a 2006 Spec Enduro with that "special" DHX5Air, with sealed IFP chamber. Rebound and ProPedal are non existent, even fully closed. What are my chances to self-service that shox? I heard that I can't bleed it by myself due to that special IFP.

    I'm in Spain and there is no official Fox service right now... pse help!!!

    Thanks!

    Unfortunately, in your case, you will not be able to service this shock and it will have to be sent back to a service center. Unless of course, you can source out a charging tool.

    A motorcycle shop might be a great place for assistance.

  44. #44
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    Unfortunately, in your case, you will not be able to service this shock and it will have to be sent back to a service center
    Even if the IFP is left alone?
    CRAP... I'm in the wrong gear

  45. #45
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    Good question rockhop. What will happen if i try to bleed without opening the IFP chamber? Can it be done? Will it solve my rebound problems? Why am I asking so many questions?

    TNX!!!

  46. #46
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    Quote Originally Posted by Booty-farrah
    Good question rockhop. What will happen if i try to bleed without opening the IFP chamber? Can it be done? Will it solve my rebound problems? Why am I asking so many questions?

    TNX!!!
    If you opened it up without releaving the presure it would change your IFP position by pusing it down.

  47. #47
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    Quote Originally Posted by forceyoda
    If you opened it up without releaving the presure it would change your IFP position by pusing it down.
    True. But I'm guessing that there's no pressure in my IFP at all. No rebound, no ProPedal. no bottom change when IFP fully closed. Can that be the cause of my bad working shox?

  48. #48
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    I would like to know the method used to fill the IFP chamber with nitrogen. Anyone?

  49. #49
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    Quote Originally Posted by Booty-farrah
    I would like to know the method used to fill the IFP chamber with nitrogen. Anyone?
    DHX doesnt use nitrogen in the IFP chamber. I bled mine by following the guide and it was easy. The IFP has terrible stiction in a tight shock, I doubt letting the air out of the chamber moved it at all. Once mine was bled you really had to push it before it would budge.

    What do you mean that yours is special and has a sealed chamber? Do you have a schrader valve on top of the piggyback reservoir? Is there a rubber plug that covers a needle port? Your shock must be some bastard version that specialized likes to use. I think they also threw a pike version out there without moco on some bikes.

  50. #50
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    Yes, unfortunately I have one of those fu**ing Specialized versions. One of my friends, a good moto mechanic can help me with the nitrogen stuff but I don't know how to fill it.

  51. #51
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    To charge the shock follow the above assembly steps. However, instead of using a shock pump you are going to use a needle to inflate the chamber with Nitrogen up to 150-175 psi

  52. #52
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    I guess that the little white cap have to be removed, right? And after filling the IFP, must I cover that port?

  53. #53
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    @Booty-farrah

    I don't know for certain, but it could be possible to remove the grub-screw/plug from the piggyback, then drill and tap what's left to accept a standard air valve. Or see about buying a replacement end cap from Fox, or salvage the part from someone with a dead unit. At least then you could go about sorting the shock in the usual way.

    It sounds like the shock's in a bad way as it is if you haven't any rebound at all, so what's to lose?

  54. #54
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    @EmanResu

    Thanks. I think is not possible to install a valve or end cap replacement due to lack of clearance between the shox and the frame (that's why Spec put that "special" DHX5). I'm in the process of bleeding the circuit, I have removed the white plastic cap (BTW very easy to remove with a soldering iron) and emptied pressure from IPF with a needle. Oil circuit sounds like thousand farts so that's the problem!
    Next days, I will try the bleeding process described in his post. Cross your fingers!! haha

    Thanks

  55. #55
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    Yeah, I was thinking you could countersink it similar to a standard DHX.


  56. #56
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    Nice, informative, thread.

    I think whomever assembled mine used ft-lb rather than in-lb on their torque wrench. Getting that stupid rubber seal/plug out of the eyelet bleed port was lots of fun too (I'll be replacing that with a screw/o-ring).

    Working on this thing is a pain in the a$$ compared to my Roco.

  57. #57
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    @Mrwhlr

    I replaced the grub screw/rubber plug affair with a solid grub screw I happened to find here which turned out to be a perfect fit. Prior to finding that I was thinking about just using a ~3mm ball bearing in its place instead. I don't really see a need to have the rubber plug unless you're working with needle syringes.

  58. #58
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    As far as I know, they put those nylon balls with a sort of a striker pin and a hammer and the main purpose is simply to keep ports clean (my guess...).

    BTW, i'v been thinking about a different bleeding process. My approach is this:



    Remove IFP piston center screw. Fill with oil until IFP chamber overflows. put IFP piston screw. Keep filling until main piston overflows, put screw.

    Maybe i'm wrong but to me is the cleanest way to bleed/keep air out...
    what do you think about it?

  59. #59
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    Quote Originally Posted by Booty-farrah
    As far as I know, they put those nylon balls with a sort of a striker pin and a hammer and the main purpose is simply to keep ports clean (my guess...).

    BTW, i'v been thinking about a different bleeding process. My approach is this:



    Remove IFP piston center screw. Fill with oil until IFP chamber overflows. put IFP piston screw. Keep filling until main piston overflows, put screw.

    Maybe i'm wrong but to me is the cleanest way to bleed/keep air out...
    what do you think about it?

    Somebody has done it before like that... I'm too lazy to search for the thread, but it's perfectly feasible.
    Check my Site

  60. #60
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    Long shot but does anybody have the part number for the bit the valve fits into. This part.


    I have the Specialized DHX 4.5 and want to convert it to a full 5 but am struggling to get the parts.

  61. #61
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    Bloody fantastic. I somehow managed to convince the UK distributor to sell me the assembly. A wopping £36 inc postage. Soon I will be able to service my DHX and upgrade from a 4.5 to a 5! Fantastic.

    I will post part numbers here for others if they are on the packaging when it all arrives.

  62. #62
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    I know I'm probably the only one still reading this but I just got the parts to convert my DHX to a full 5.0 as far as I am aware you be able to use this kit to adjust all nitrogen charged DHXs to air valve DHX 5s. Here is the part list.

    1x 813-00-050
    Reservoir End cap Assembly (this it the boost valve air pressure adjust part)

    1x 210-03-075
    Bottom out adjust knob (the big blue knob)

    1x 010-00-004-A
    Air Valve and cap (strangely not included with the assembly)

    2x 018-01-007-A
    Grub screws (to hold the big blue knob on and also strangely not included with it)

    Now people will know what to ask for if they fancy doing the conversion themselves. I have also got a needle valve (like the ones fox use) to remove the nitro, this can be used to also charge RP shocks with air instead of nitro so they can be home serviced. I will follow up in a week or two when I have done the conversion and hopefully it will all fit together and work properly.

  63. #63
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    That's very handy info that, Bad Knees, thanks.

  64. #64
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    Conversion done with no bad side effects it rides much better now. I have also packed the HV part of the air can with grease because they don't do a LV can for my shock size. The whole bike feels much better because of this. I barley notice the shock doing its job now. That was a bit worrying at first because it was so obvious that it wasn't working properly so I keep looking at it and trying to feel it doing something badly but I can't. I didn't do an air can service at the same time but I might do one in the spring when it dries out a little.

    Over all I am pleased with the shock now I would quite like a little leaver for the propedal like on an RP3 so i can have it off medium and high as it is a pain to adjust with the dial for different types of riding. The shock has been massively improved by what I have done partially because it needed an oil change anyway. I might have another fiddle and put an extra shim in the compression stack next time I service it but that is a while away yet.

    Thanks for everybody's input as this thread really encouraged me to do this at home and save the £150 it costs to get Mojo to do it.

  65. #65
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    DHX Air Stantion? replacement

    Guys, new to the thread and looking for help.

    I have a 2007(I'm guessing) DHX 4.0 Air (with no air valve on the Propedal chamber) that has an enlarged or worn eyelet on the stantion side The DU bushing slides right through the hole.

    Can someone walk me through the process of changing the stantion, as I have purchased a functional replacement? I'm guessing it comes apart pretty easily as it seems this is not a step mentioned much in the posts I've found here. It seems pretty tight and I want to make sure I relieve any pressure before opening it up.

    Refilling it and Bleeding it sounds like the tougher task and it is well documented here.

    Thank you,
    John

  66. #66
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    I don't know what might be best, but I'd have to ask how you intend to repressurise the piggyback afterwards. I don't think there should be much issue releasing the internal pressures as there's a number of ways to do that. Stripping it down and replacing the shaft shouldn't be too difficult either.

  67. #67
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    Great thread
    I just have a quick question as im going to do this to my dhx...
    I get that the main aim is to have no air between the ifp being set and the main shaft fully exstended. "am i correct in thinking this ?"
    So 1st question is how much 85w oil did you put behind the ifp and 2nd do all o rings need to be lubed if so will silicon grease be ok??
    Cheers Wils

  68. #68
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    I'm not too sure what you mean with regards air between the ifp and main shaft extended there. It's just important that the main shaft be fully extended before reinserting the IFP and setting its depth. If the shaft wasn't fully extended prior to setting the IFP depth, then when later extended the IFP would be pulled further down deeper into the piggyback to a depth below what it should be.

    I only put a little of the 85w oil (maybe 1cc) on top of the IFP there as a way to help it stay better sealed and lubricated in the same manner as one would when servicing the main air piston seal. Doing this probably did help my own unit to stay sealed better for a while, though as it turns out the IFP o-ring was fairly worn in my case so did still require replacing at a later time as I found air would progressively work its way back into the damping oil. In hindsight I can see that it was this o-ring that was likely the cause of the original introduction of air into the damping oil which was the reason I needed to dive in there to service it. If you find you're choosing to service your own shock for this same reason then I would recommend replacement of that IFP o-ring where possible (the o-ring itself is a common size and easily found).

    I wouldn't say all o-rings need to be greased as such during assembly, though it's certainly a good idea to have them lubricated prior to being inserted/fastened to help them seat and seal properly. What I wouldn't recommend for instance would be to remove o-rings, clean them, then reinstall them into a clean housing, then fasten them. They need some lubricant on them ideally before assembly. I haven't used silicone grease so couldn't say too much about that, though to be honest lubricating o-rings with damping oil or a heavy oil (like I used) should be perfectly sufficient. I guess a good slippery grease could be useful if installing something a bit tight though, or where it would be preferable to have a seal slide over a rough surface (like sliding the IFP o-ring over the bottom out adjuster threads) with the minimum of resistance. I've not found this to be particularly necessary though when I've redone my own shock here at other times.

  69. #69
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    Top man cheers for that , all i need is time to set aside and get cracking at it. Oh and just to b sure the depth of the IFP is measured to the flat of the IFP body and not the top of the threads on the IFP.
    Cheers Wils

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    Nice one Eman! This is great info thanks for taking your time to post this.

    Hope you are still around somewhere.

    I was wondering if you could bleed the system via the IFP valve (with core removed) with a stans 'The Injector!' a large syringe with schrader vave adapter, for filling tyres with tyre milk.

    Might give this a go tonight!

  72. #72
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    nice thread!
    Only want to add that IFP depth for custom 2.75" (70mm) stroke is 1.415 (36mm): Fox DHX Air and Coil: oil viscosity and IFP depth
    Here's biggest resolution picture that I found:
    n/a. at Interbike 2008 in Las Vegas, Nevada, United States - photo by mikelevy - Pinkbike


    Also be careful when inserting floating piston back to its IFP depth - it spits very quickly fluid from eyelet because of stiction - it went directly in my left eye but I cleaned it immediately with soap!

  73. #73
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    Also be careful when inserting floating piston back to its IFP depth - it spits very quickly fluid from eyelet because of stiction - it went directly in my left eye but I cleaned it immediately with soap!

    Ha, I've had this happen to me on several occasions.

    I like using a socket to help press the IFP down to the proper depth. Now if the IFP decides to burp the socket captures the fluid, not my face

  74. #74
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    @SlowUpFastDown

    Yeah, it should work fine I think, I don't see why not, though beware that the oil could make the syringe rubber expand greatly over time (maybe you'll get away with it if you give it a good cleaning after use). Invert the air can on the shaft with the grub screw removed and I reckon it should make light work of bleeding it though.

    @codename47/cort

    Yep, a good tip there (done the same here numerous times) .

    I ended up cutting a piece of 20mm plastic pipe here at just the right length so that all I need do now to set the IFP depth is follow that in behind the IFP then screw the BO adjuster in behind that (also helps avoid above problem). Then remove the BO adjuster and conduit length and the IFP depth is spot-on.

    BO adjuster <-> plastic pipe <-> IFP

  75. #75
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    A little topic kick.
    I'm experiencing problems with dismantling my Dhx 4 Air. The air sleeve is of, piggyback open but I can't unscrew the shaft cap from the main piston. I've used quite some force but I'm scared to bent it or break the eyelet where the Du-bushing is.

    Anyone some tips. I guess for the oil swap it is not really necessarily to unscrew it although I'd like to do it to clean and inspect everything.

    Thx!
    Michiel

  76. #76
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    Quote Originally Posted by EmanResu View Post
    Cheers Nick_M2R / Furrner.

    Had a root about for some IFP depth values and came up with the following numbers;

    Code:
    Metric ;
    190mm, 50mm = 32mm
    200mm, 50mm = 32mm
    200mm, 57mm = 33mm
    215mm, 64mm = 34mm
    222mm, 64mm = 34mm
    241mm, 76mm = 38mm
    
    Imperial ;
    7.500, 2.00 = 1.25
    7.875, 2.00 = 1.25
    7.875, 2.25 = 1.30
    8.500, 2.50 = 1.35
    8.750, 2.50 = 1.35
    9.500, 3.00 = 1.48
    The metric values are rounded slightly to convert from imperial but are very close. They may be different for coil versions, I don't know. * Don't quote me on them.*
    IFP depths are the same for DHX coil and air for a given shock travel. They have identical shaft ODs and use the same reservoir lengths (depending on the travel).

  77. #77
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    Hello
    does anyone know the measurements of the o-rings (size) which need for DHX 5 air rebuilt?
    thanks

  78. #78
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    EmanResu thank you very much. Just followed your steps to bleed an dhx air 4.0. Working like a charm again. Though i did not reach the point of the hydrailic lock.
    I could still compress the shaft about ~5mm. I retried several times but could not improve any further. But now in the bike i can not hear or feel any air in the damping so im happy.
    I plugged in the rubber seal in the oil the removed the oilbath and screwed it close afterwards. What do you guys do?

    Btw here are a complete list of ifp depths.
    FOX DHX 5.0 (inkl. AIR):
    190/50: 1.25" (31,75mm)
    200/50: 1.25" (31,75mm)
    200/57: 1.30" (33,02mm)
    216/63: 1.35" (34,29mm)
    222/70: 1.415" (35,94mm)
    241/76: 1.475" (37,47mm)

    FOX DHX 4.0 (inkl. AIR):
    190/50: 1.05" (26,67mm)
    200/50: 1.05" (26,67mm)
    200/57: 1.10" (27,94mm)
    216/63: 1.15" (29,21mm)
    222/70: 1.135" (28,83mm)
    241/76: 1.375" (34,93mm)

    FOX DHX 3.0 (inkl. AIR):
    190/50: 1.15" (29,21mm)
    200/50: 1.15" (29,21mm)
    200/57: 1.20" (30,48mm)
    216/63: 1.25" (31,75mm)
    222/70: 1.25" (31,75mm)
    241/76: 1.375" (34,93mm)
    Last edited by winterkiter; 03-22-2013 at 01:54 PM. Reason: add the ifp depths

  79. #79
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    In the Rock shox Manual for the Monarch Plus page 31 ff.
    http://cdn.sram.com/cdn/farfuture/zN...4158_rev_a.pdf

    I found a different procedure for bleeding the damper, I will try that the next time.
    cheers flavio

  80. #80
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    Fox Shock rebuild instructions (Click on model):
    Rear Shock Service Home

    Fox DHX 5.0 Air Diagram:
    http://www.dhfr.ru/fox/Content/Parts...3-002_RevA.pdf

    Bubble drawings and a lot of other information including ifp settings.
    http://www.dhfr.ru/fox/Content/Maste...hocks31605.pdf

    Other links here:
    FOXHelp Service System

  81. #81
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    Howdy fellow DHXers! I've got a quick question. I have a 5.0 7.875x2 and I just finished an oil change and bleed. When I set the IFP depth, I was curious to see how far it would go down. It seems that 32mm is all the way at the bottom. It won't go any further. Can anyone else confirm that this is correct? I feel that it shouldn't be bottomed out in the reservoir but then again I'm not a suspension engineer lol

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