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  1. #1
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    X-Post Fox RP3 - Unserviceable?!?!?!

    So, I've been around motorsports, snowmobiles, dirtbikes and the like over the years. I've also been biking over half of my life here on earth, so I know a few things about servicing Fox shocks. This brings me to my current rant.....

    I have an older RP3 shock that needs new damper oil and a nitro recharge. I've done the air sleeve (many times) and I DO NOT NEED any custom valving (aka Push). Apparently NO ONE, I mean NO ONE other than Fox and Push can recharge the nitro?!?!?!

    When I used to re-valve my snowmobile shocks we had a huge bottle of nitro in the shop. A matter a 30min to re-valve, re-charge and I was back riding my snowmobile seeing what effect the changes I made had to the suspension. It was no biggie. Anyone could do it. Seriously, it isn't hard to recharge the nitro with the needle tool.

    This brings me to my current dilema..... I don't want to spend $100+ dollars just to rebuild the shock to normal condition. I just want to refill the damper oil and recharge the IFP chamber. Hell, I'd be just fine using air instead of nitro, but that doesn't seem possible without the tool. (which NO ONE has, except Fox and Push)
    What is everyone doing with this situation? I talked to Fox and they want $120 for a full rebuild! I'd go the Push route for a little more than that, but I'm fine with the Comp and Rebound functions.

    Has anyone found a cycle/sled shop that can recharge the nitro side of things? I'm worried the needle guage is slightly larger than what the MTB shocks need.
    I've found some good info online and even found a massive zip file of Fox documents with exploded views, specs, and the like for my shock. IFP depth and the like. The file even has a service update in which Fox is telling dealers that the Nitro side of my RP3 is now getting pressurized to 400psi instead of the 'normal' 300 psi. I don't even have the means to pressurize something to 400psi......

    I'm really frustrated with Fox right now. Great product until it needs servicing and then I'm supposed to pay almost half of the cost of a new shock, just to rebuild my old one!?!?
    I am more than competent and confident to do this myself, but how?

    Any help on the matter is appreciated and I know I'm not the first to ***** about Fox's proprietary damper. Feels like a Monopoly with Fox and Push being the ONLY ones that can work on these.

    /Rant, Just needed to get that off my chest!

    Please tell me I don't have just 2 options!

  2. #2
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    I think you'll find the information you're looking for here:
    Breaking and entering the damper circuit on a Fox air shock

  3. #3
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    Quote Originally Posted by bad mechanic View Post
    I think you'll find the information you're looking for here:
    Breaking and entering the damper circuit on a Fox air shock
    Thanks, I've reviewed that like the bible.

    Only problem EVERYONE has is getting the right amount of pressure into the chamber and them closing the valve without any escaping.
    The RP3 needs 400psi. That's a lot!

    Here's the path i'm on......

  4. #4
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    I'd suggest making your own slotted allen key, like the guy in that thread did. If I remember correctly, he just dremeled a slot big enough for the needle in the allen key, so he can tighten down the rubber pellet before removing the needle. Also, if you have the tools, you could consider just drilling it, tapping it, and installing a schrader valve.

  5. #5
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    Not a 'bad' idea, but for the $40 for the needle valve it would be a lot cleaner/more precise!

    Thanks for the help

  6. #6
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    Get the needle. As you say, you cannot get to 400psi with a shock pump and DIY fill needle. With a shock pump you can get to around 300psi.

    I got the needle and 600psi guage for $60. I just take it with me to my local moto store and they hook it up and fill the shocks. When playing around with the valving I just use air at ~300psi.

    Search for "nitrogen safety fill needle" and there's a number of online stores selling the genuine fox version.

    If you pull your RP3 apart, let us know what reb/comp tune it is and what the shim arrangement is. I've collected some info on medium and firm tunes here. It would be good to get a database going of this stuff for future reference.

  7. #7
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    Tig. Thank you!
    That is exactly my intention. Is the needle tool the same for the moto industry? I've only seen the 1 offered by Fox.
    I will most definetly be playing with shim stack, so i will contribite what i can.

    sent from my hand-held computer

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    I have used this needle with great success. http://www.motionpro.com/motorcycle/partno/08-0075/ I use my shock pump( with adapter fitting) for 300-350 psi and have also used a 10# bottle of nitrogen from a local supplier fitted with a 600 psi gauge/regulator set up.

  9. #9
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    Excellent info. Thank you.
    How many times are you guys able to pierce the interior pellet before it stops holding?

  10. #10
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    How many times are you guys able to pierce the interior pellet before it stops holding?
    Once only.

    Get some 2mm rubber gasket sheeting and a 7mm hole punch. I've also tried making the pellets using a mold and heavy duty silicon rubber. This has also worked OK but I'm not sure how long the silicon rubber molded pellets will last.

  11. #11
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    Buy o-ring cord, cut a slice. Works great.
    Owner of www.shockcraft.co.nz and NZ Manitou Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  12. #12
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    Quote Originally Posted by Dougal View Post
    Buy o-ring cord, cut a slice. Works great.
    Excellent tip!

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    Quote Originally Posted by Dougal View Post
    Buy o-ring cord, cut a slice. Works great.
    Thanks again Dougal!

    Just had some 7mm o-ring cord come in and it works a treat to make the nitro seal pellets out of.

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    Good tip about the nitro tool. Might have to get one.

    Regarding my own adventures (in http://forums.mtbr.com/showthread.ph...52#post8211652) I just built that bike back together and updated the post. I plugged the rebound adjuster rod (internally) and ditched the platform functionality as well as re-arranged some washers on the main piston and everything seems to be working very nicely now.

  15. #15
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    Ok. Needle valve ordered (with schrader adapter) and should be here this week.

    One question for you guys: where are you sourcing your damper O-Rings?
    Or any of the damper seals for that matter? I've got the p/n's for individual O-Rings and 'kit' p/n's for the rebuilds, but Fox won't sell them outright. None of the shops can get them....
    Looks like you guys across the pond have better access, but ordering such small parts to the states seems too expensive.

    Are you just mic'ing the size/diameter and replacing with the like?

    --------------------------------------------------------------------------------------------------------------
    Ola H.
    -saw your post on the rebuilt shock. One question though.... With only a couple hundered psi in the damper, how are you getting adequete rebound? I thought the rebound/pro-pedal were directly affected by the internal psi?
    I have a document from Fox stating that the internal psi was to change from 300 to 400psi as of 2006. (this is for the RP3, RP2, RP23)
    So with only a couple hundered I'm suprised you can even ride the shock....

  16. #16
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    Quote Originally Posted by HomegrownMN View Post
    Are you just mic'ing the size/diameter and replacing with the like?
    Yes. O-rings are almost never proprietory parts.
    Owner of www.shockcraft.co.nz and NZ Manitou Agent.
    www.dougal.co.nz Suspension setup & tuning.
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  17. #17
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    Quote Originally Posted by HomegrownMN View Post
    Ok. Needle valve ordered (with schrader adapter) and should be here this week.

    One question for you guys: where are you sourcing your damper O-Rings?
    Or any of the damper seals for that matter? I've got the p/n's for individual O-Rings and 'kit' p/n's for the rebuilds, but Fox won't sell them outright. None of the shops can get them....
    Looks like you guys across the pond have better access, but ordering such small parts to the states seems too expensive.

    Are you just mic'ing the size/diameter and replacing with the like?

    --------------------------------------------------------------------------------------------------------------
    Ola H.
    -saw your post on the rebuilt shock. One question though.... With only a couple hundered psi in the damper, how are you getting adequete rebound? I thought the rebound/pro-pedal were directly affected by the internal psi?
    I have a document from Fox stating that the internal psi was to change from 300 to 400psi as of 2006. (this is for the RP3, RP2, RP23)
    So with only a couple hundered I'm suprised you can even ride the shock....
    Orings: by luck. My neighbour works in the oring business and by using a few different suppliers he managed to stock me up.

    Low psi: yes that is what I discovered without even mounting the shock... That is that the pp need the super high pressure. So if you you read the full story to the end, you'll see that I simply took the pp circuit away and plugged whole inside the redbound rod there the pp rod usually go. I'm not a fan of pp anyway and since this area seem to be the no 1 failing point of these types of shocks I did it like this to never be bothered by this particular leak again...
    Rebound does not seem te be affected though. In fact, the rebound now has a bigger tuning range from ultra slow to super fast and it seems very easy to find a sweet spot. I think the removal of the pp assembly simply leave more free space for the oil to flow, even with the too low gas pressure in the oil section. As Dougal mentioned, the main promlem one might suspect would be that the oil damper suck air in hits that yield a fast rebound rate. And after a few rides I might have some slight sounds from air in the shock, but still very little and it might even be a result from not enough careful bleeding from the start.

  18. #18
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    The Float R on my wife's bike only lasted a month with 300psi in it. It sucked in enough air that the rebound was inconsistent and clunking (again).

    I threw a coil back on, I'll revisit that shock later.
    Owner of www.shockcraft.co.nz and NZ Manitou Agent.
    www.dougal.co.nz Suspension setup & tuning.
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  19. #19
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    Quote Originally Posted by Dougal View Post
    Buy o-ring cord, cut a slice. Works great.
    Thank you, thank you, thank you!

    Great tip. Denver has the luck of having an amazing O-Ring supplier and they happend to have 2.5' of 7mm cord that wasn't 'in the system,' so I got it for free.
    I've got enough material for the next millenium!

  20. #20
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    Well i recieved the needle safety tool and was able to deflate my shock's nitrogen. I then replaced the rubber puck and was able to reach 300psi with my Fox pump. Held air just fine.
    I'll be tearing into it shortly along with an older Talas R shock i picked up for $20 to use for donor pieces. Hopefully the Talas will have diff shims than my RP3 so i can play around.
    The only mod i made to the needle tool was to shorten the needle. Dia is right, but length was too long. They're meant for large body shocks so a few mm's shorter worked fine.
    Joe

    sent from my hand-held computer

  21. #21
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    Couple of things to watch out for.

    Depending on your bleeding technique, the IFP volume may increase as you purge out air bubbles so allow for it when you set IFP depth.
    The bleed screw tightens down on a plastic pellet, not sure how many times the plastic pellet can be used before it leaks.

    Your not going to have many options with the high speed compression, it uses disc springs instead of shims. The disc springs don't like to travel too much or they fatigue and break. If you want to use a single disc spring, try to shim it to make up the difference in compressed height.

    In my opinion the compression tuning is not the biggest performance problem in the float shocks. Have a good look at the rebound circuit, seems to me Fox has constrained it so the propedal circuit is more effective. Pedal bob is up and down, the compression side of things is more obvious but look what happens to low speed rebound flow when propedal is engaged and the plunger blocks the hole in the piston bolt. Now picture what would happen if the HSR was too active, the propedal effect would be greatly diminished on the rebound side. I think Fox has chosen to set HSR on the constipated side to increase the effectiveness of propedal.

    If your shock has been packing down in rock gardens and the rooty stuff you can drill those three HSR holes bigger but be careful, more port area equals more port flow as well as more surface area against the shims. Now the shims are going to open earlier as well.

    One side effect of a too soft compression tune is that propedal will get used more often and that impedes LSR flow. The problem I had trying to tune these shocks is everything affects something else and its not always apparent how at first.

  22. #22
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    Good info.^
    I've sucessfully rebuilt my RP3 & the girlfriends Float R.
    I was able to tap the threads on a donor Fox schrader vavle and this is holding pressure just fine for the nitro chamber-300psi.
    I'll get pics up soon of both shocks & their respective shim stacks. My '05 RP3 has some interesting valving...
    I'm off to Miami for a wedding.
    Joe

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  23. #23
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    Interesting.

  24. #24
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    We the people ... Here we go....

    Sorry for the 'Tease' and run post from last week. Had to travel and didn't have time to do a full 'n proper write up.
    So, here we are. I recieved my 'Nitrogen safety needle' from Poly Performance the other week and proceeded to disassemble my RP3. This RP3 is a late '05 early '06 model from my Giant Trance. The Trance is also a first gen that I bought as a frame only from the lbs that same year.
    *I will refer to the 'Nitro chamber throughout, even though I am filling with ambient air.
    *I have reset the IFP to factory settings and pressurized the nitro chamber to 300psi.


    The pressure that was remaining in my shock was pretty negligable as it sat. I had definetly lost some over the last ~5yrs. I had performed regular 'air sleeve' maint. every other year and not too long ago I fell victim to the ever common 'stuck-down' syndrom.
    Now realizing that issue, I'm sure that's where some of the nitro snuck out.

    Here is the vavling assembly.


    Seems to have both firm comp. and firm rebound valving.

    I was able to find a donor shock on CL for $20 that I figured at best could be used for internal parts etc. and worst case I'd have it for bushings. It was an ~'05 Talas RL rear shock. I disassembled that shock and to my pleasure I found the shims to be useable along with the schrader valve, O-rings, and many other small pieces.
    Here is a pic of the Talas. Only used for shims and schrader


    I realized after reviewing many exploded views and pics that the pos air schrader valve was a 36tpi where it threaded into the body. This is only important because the tpi for the grub screw (where the nitro is held) is 24tpi. So, I decided that I'd try tapping my donor valve to see if I could use it in place of the grub screw for the nitro chamber.
    I realize that it seems mildly redundent to purchase the nitro safety needle and then try to fit a schrader valve for the nitro chamber, but I had only found a few saying that they had tried and found it mildly successful. Figured I'd give it a go since I had nothing to loose. Also had the advantage of working with the 1st gen Trance frame and I have MORE than enough room to turn the bottom of the shock body 180 degrees. Running the schrader valve for the nitro opposite the PP lever.

    Also had a 24tpi Die at work, so this was a no brainer. I had no problems turning new courser threads into the finer threaded body. I had to turn down the 'hex' area that allows you to tighten the schrader, but after removing them I filed 2 flat spots to allow tightening.

    *One thing to note. I had read where others had tried the schrader valve for the nitro and had a problem leaking due to the high pressures in there. After a few attempts at filling through the schrader valve I realized that I needed to tighten the valve 3/4 of the way, Fill to 300psi and tighten the valve down before releasing the pump. This effectivley 'pinches' the rubber seal the is behind the schrader valve. Therefor the valve is not responsible for holding the pressure, the rubber disk is.
    Here it is holding pressure just fine.


    Filled 'er up and went for a ride. Was a beautiful day before I was to leave on vacation and I had to see if I was successful. I had a great ride! 1st off, the shock NEEDED a rebuild in a bad way. I realize that after 5yrs of abuse the shock fluid was more than done for. So, with that in mind, everything rode great, the shock held pressure on both ends just fine and I'm glad to say that I was able to rebuild this RP3.



    I then left for a weeks vacation (from which I just returned) and checked the air pressure in both the pos main body and the nitro chamber today. Both holding just where I left them. 175+psi and 300psi in the nitro chamber.

    Here's a few thoughts since I've now torn the shock apart a few times and have been playing with the valving.
    I noticed a couple years ago that my ProPedal lever had become slightly,...well...limp. Thats the best way I can describe it. When flicking it between the 1-2-3 position, it would just slide over without the same pazzaz as day one. Since the rebuild I realize this is directly related to the nitro chamber pressure. After doing the damper rebuild, but before pressurizing the nitro chamber, the PP lever felt the same. As I pressurized the nitro chamber the lever became firmer and more positive feeling. After tearing the shock apart a couple times now (having the nitro chamber air leak once and the lever going 'dead') I realize that the nitro chamber pressure is directly loading the damper and thus, loading the PP plunger.
    So, if your PP lever feels 'dead' or 'limp' I'm gonna say that your shock needs a full rebuild to repressurize the nitro chamber. Just my observation. Now that I've rebuilt mine, it feels amazing when I throw it around.
    Also, Fox offers great info on rebuilding thier Airshox line of shox for snowmobiles and ATV's. Refer to their detailed pics and descriptions for info on depressurizing the nitro chamber and also refilling.
    Last edited by HomegrownMN; 07-27-2011 at 11:45 AM.

  25. #25
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    Awesome.

    Two questions

    1) What was the IFP depth and how did you set it?
    2) What was the bleeding procedure?

  26. #26
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    Not sure what length shock is on the Trance. IFP depth on 165mm stroke Fox shocks is 1.9", IFP pressure should be 400psi.

    Bleeding these shocks is extremely easy. Once IPF depth is set, fill damper to the brim with oil, remove bleed screw and ball on damper assembly, make sure damper rod is extended as far as possible, insert slowly into damper and excess oil will come out the bleed screw. Put ball and bleed screw back in place.

    DO NOT cycle the damper until you have the IFP up to pressure.

  27. #27
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    Quote Originally Posted by tacubaya View Post
    Awesome.

    Two questions

    1) What was the IFP depth and how did you set it?
    2) What was the bleeding procedure?
    1) IFP depth is 1.90" for my 165x38mm shock (6.5x1.5)
    Set using a digital caliper.
    2) I followed the procedure outlined in the Fox AirShox directions.
    They specifically tell you to depress the piston assy. before refilling with nitro (air) and as the nitro chamber is filled the piston will rise to it's proper height.
    Not to contradict what Tig said, but I've had zero problems rebuilding my shock this way.

    And I'm running ~315 psi. This seems to work just fine. I havn't had any problem with losing pressure or the pos and neg air mixing.

  28. #28
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    Download this file and many (all) of your questions will be answered.
    There are IFP depths, torque values, pressures, etc...

    The Bible: http://sendspace.com/file/gp9k3p

    Also, here is the site for the snow airshox: http://service.foxracingshox.com/powersports/index.htm
    Look under 'rebuild procedures' for the Float & Float2 and the info will pertain to the MTB side of things.
    Starting on page 15 of the rebuild describes the method I have used when rebuilding my RP3.

    Joe
    Last edited by HomegrownMN; 07-29-2011 at 08:30 AM.

  29. #29
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    Quote Originally Posted by HomegrownMN View Post
    ...
    They specifically tell you to depress the piston assy. before refilling with nitro (air) and as the nitro chamber is filled the piston will rise to it's proper height.
    Not to contradict what Tig said, but I've had zero problems rebuilding my shock this way...
    You can stroke the piston IF the bearing assembly is not screwed down onto the shock as you will not build up pressure in the shock this way. If you do this, you will need to top up the damper with oil before puting screwing the bearing assembly on.

    Once the bearing assembly is screwed on, if you stroke the shock without the IFP being at full pressure, the IFP will move and there is no amount of pressure in the IFP that will bring it back to the proper position. The damper will be full of too much oil (if you topped it off after the IFP has moved) or you will have air in there (if you stroked it with the bleed screw open).

    Remember, the IFP is there to allow an increase in volume of the damper due to oil displacement caused by entry of the shock shaft as the shock compresses.

  30. #30
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    Well I was able to put some good time on the bike lately and can say for sure that the action of the RP3 is greatly improved! The fork (2011 Manitou Minute) and RP3 are working together better than I have ever remembered.
    The RP3 felt like it was tracking better through the rough and the minor shim changes I had made seem to help more than hinder.

    I rebuilt the shock again after the ride and pressurized the nitro chamber as per Tig's instructions with no percievable difference. I'll be riding again tonight to confirm.

    The only thing I noticed was that I lost a little of the rebound adjustment 'range.'
    Meaning that the rebound is still controllable, but doesn't have as much adjustability.
    This may be due to the fact that I added a few shims to the comp stack and this may have pushed the piston a little too far away from the rebound needle. That is the only thing I can come up with.
    Otherwise all is well. The PP still has a percievable difference between 1-2-3 settings.

    Joe

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    Top work. You can get some rebound adjuster range back by pulling one (or even two) of the really little washers that space the piston from the shaft. This will put the rebound bypass port closer to the end of the rebound needle and give you some rebound adjustment range back.

  32. #32
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    So the procedure is:

    1) Insert IFP and set it at the correct depth.
    2) Fill with oil and carefully insert piston assembly. The piston should be just below the oil. Stroke it slowly so air escapes and then thread main cap avoiding any air entrance (using bleed screw?)
    3) Compress the shock to verify IFP depth (no interference)
    4) Fill it with nitrogen/air.
    5) Grab a beer

    Seems the safety needle + 400 psi regulator + nitro tank + 7mm o-ring chord for plugs is the "factory" method.

    Sounds good?

  33. #33
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    Quote Originally Posted by tacubaya View Post
    So the procedure is:
    ...
    3) Compress the shock to verify IFP depth (no interference)
    4) Fill it with nitrogen/air.
    ...
    Do not compress the shock without fill pressure in the IFP so 3) 4) becomes:

    3) Fill IFP chamber with nitrogen
    4) Compress the shock to verify IFP depth (no interference) - optional - you'll need a hand dynamometer or other lever-type setup - if IFP is set right there will be no interference
    5) Fill it with air

  34. #34
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    Quote Originally Posted by tacubaya View Post
    So the procedure is:

    1) Insert IFP and set it at the correct depth.
    2) Fill with oil and carefully insert piston assembly. The piston should be just below the oil. Stroke it slowly so air escapes and then thread main cap avoiding any air entrance (using bleed screw?)
    3) Compress the shock to verify IFP depth (no interference)
    4) Fill it with nitrogen/air.
    5) Grab a beer

    Seems the safety needle + 400 psi regulator + nitro tank + 7mm o-ring chord for plugs is the "factory" method.

    Sounds good?
    The part that is not clear from the Fox instructions is whether the oil volume is set with the piston all the way in or all the way out? I will assume it is with the piston all the way out.
    My advice is based on working on shocks other than Fox, but I would say:

    1) Set the IFP depth with the IFP valve OPEN. Use the recommended value or push the IFP down with the damping piston till it goes down as far as it would under full compression. (This would involve screwing on the main cap)
    2) CLOSE the IFP valve while at 0 PSI
    3) Fill with enough oil such that only a little bit will squirt out once you thread on the main cap.
    4) Put in piston and stroke it. Add or remove oil to fulfill step 3.
    5) Thread on the main cap with the piston slightly below the oil level. The bleed valve should be OPEN. Hold the cap steady with the bleed hole oriented upwards and rotate/screw on the main body. Some air and oil should squirt out the bleed hole.
    6) Your job is now to get all the air out of the oil chamber WITH THE PISTON IN THE NEARLY FULLY EXTENDED POSITION. With the bleed hole oriented in the highest position, compress the piston to push out air/oil or extend it to suck in more oil.
    7)CLOSE the bleed valve, but don't crank down on it too tightly. Push the piston down all the way.

    7a) If you feel a clunk before it bottoms, you've hit the IFP with the piston. You need to get more oil into the chamber. With the piston in the fully compressed position, OPEN the IFP valve. This air space will be slightly pressurized and a little air will come out. CLOSE the IFP valve. OPEN the bleed valve, and pull the piston outwards to suck in more oil.

    7b) If you feel too much progressive force as you push down the piston, you set the IFP too low. OPEN the bleed screw and push down on the piston to squirt out oil.

    8) Crank down the bleed screw all the way and pressurize the IFP.

  35. #35
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    Tig, thanks to you I had a starting point with the info you had posted and an idea of what to expect inside these things!

    First off let me explain the 2 methods I have used to refill the damper oil and nitro chamber.
    1st Method:
    1- set IFP depth with a micrometer
    2- fill damper chamber with 10wt
    3- close OFF IFP chamber grub screw (sealing IFP chamber and creating a vaccum)
    4- with the piston all the way up, touching the bearing head and without the steel ball,
    slowly insert into damper oil and begin threading by hand. If oil comes out of the bleed
    port, things are all good.
    5- drop in steel ball and tighten grub screw
    6- with the nitro chamber still sealed, I depressed the piston down into the oil
    7- with the piston all the way down, I began to refill the nitro chamber to 300psi
    8- as the nitro chamber fills, the piston begins to rise
    9- air up the main chamber and ride!

    2nd Method:
    1- set IFP depth with a micrometer
    2- fill damper chamber with 10wt
    3- with the piston all the way up, touching the bearing head and without the steel ball,
    slowly insert into damper oil and begin threading by hand. If oil comes out of the bleed
    port, things are all good.
    4- drop in steel ball and tighten grub screw
    5- fill nitro chamber to 300psi
    6- air up main chamber and ride!

    I was able to put some good miles on the shock last night again (after the rebuild, WITHOUT depressing the piston) and everything was good. The shock feels really good right now!
    I'm ordering a 400psi shock pump in the next day or two so that I can play with the IFP pressure some more and I'll report back on that.

    Joe

  36. #36
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    Quote Originally Posted by TigWorld View Post
    Do not compress the shock without fill pressure in the IFP so 3) 4) becomes:

    3) Fill IFP chamber with nitrogen
    4) Compress the shock to verify IFP depth (no interference) - optional - you'll need a hand dynamometer or other lever-type setup - if IFP is set right there will be no interference
    5) Fill it with air
    Huh?

    I don't see why you can't fully compress the shock with no IFP pressure. IFP will move down as shaft occupies space and displaces volume. Then when filling it, IFP will force shaft outside and the IFP will occupy the displaced volume. Unless the IFP o-ring is crappy I don't see how the shock would aerate.

  37. #37
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    Quote Originally Posted by tacubaya View Post
    Huh?

    I don't see why you can't fully compress the shock with no IFP pressure. IFP will move down as shaft occupies space and displaces volume. Then when filling it, IFP will force shaft outside and the IFP will occupy the displaced volume. Unless the IFP o-ring is crappy I don't see how the shock would aerate.
    Thats how I understand it as well. Especially if the IFP chamber is sealed creating a vaccum.

    I've now done the rebuild both ways, and I really can't tell a difference. My IFP depth was the same after a teardown when I used the Fox method and depressed the piston before pressurizing the IFP....

  38. #38
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    Quote Originally Posted by HomegrownMN View Post
    1st Method:
    1- set IFP depth with a micrometer
    2- fill damper chamber with 10wt
    3- close OFF IFP chamber grub screw (sealing IFP chamber and creating a vaccum)
    4- with the piston all the way up, touching the bearing head and without the steel ball,
    slowly insert into damper oil and begin threading by hand. If oil comes out of the bleed
    port, things are all good.

    How do you make sure all the air is out of the oil section? Often there is air trapped inside the piston and you did nothing to remove it.

    5- drop in steel ball and tighten grub screw

    Once you do this, steps 6 - 8 become irrelevant. Stroking the piston will accomplish nothing, except to check the ifp height was right.

    6- with the nitro chamber still sealed, I depressed the piston down into the oil
    7- with the piston all the way down, I began to refill the nitro chamber to 300psi
    8- as the nitro chamber fills, the piston begins to rise
    9- air up the main chamber and ride!

    2nd Method:
    1- set IFP depth with a micrometer
    2- fill damper chamber with 10wt
    3- with the piston all the way up, touching the bearing head and without the steel ball,
    slowly insert into damper oil and begin threading by hand. If oil comes out of the bleed
    port, things are all good.
    4- drop in steel ball and tighten grub screw
    5- fill nitro chamber to 300psi
    6- air up main chamber and ride!

    I was able to put some good miles on the shock last night again (after the rebuild, WITHOUT depressing the piston) and everything was good.
    Yeah, that's because there is no difference in your two procedures once you close off the bleed screw. You are just lucky that any trapped air inside got compressed down to almost nothing once you pressurize the IFP, but your method doesn't set the ifp height consistently.

  39. #39
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    Quote Originally Posted by beanbag View Post
    Yeah, that's because there is no difference in your two procedures once you close off the bleed screw. You are just lucky that any trapped air inside got compressed down to almost nothing once you pressurize the IFP, but your method doesn't set the ifp height consistently.
    As far as I'm concerned, the piston displaces enough oil in the damper up through the bleed hole to purge any air. Once the bearing cap is threaded on the piston assembly is practically flush with the top of the damper, therefor no air should remain inside.

    I doubt I'm 'lucky' with my methods. I've rebuilt more shocks in more applications than most and feel I know what I'm doing here. And @185 lbs riding the shock for 25+ miles of Colorado's finest, with no ill effects...just sayin'

    FYI my IFP depth has been consistently the same 1.9" everytime I've torn it down. I've torn it down close to a dozen times now.

  40. #40
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    IMHO you are not doing enough to make sure that there is no air trapped inside. Having the piston extended fully when the cap is screwed down is one of the best ways to make sure there are air bubbles trapped inside and just above the piston. This is why I recommend that the piston is pre-pumped and below the oil level when the cap is screwed down. Also, I recommend pumping the piston with the bleed screw closed and the ifp at 0 PSI but closed off to check for air bubbles. This check doesn't work if you inflate the ifp.

  41. #41
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    Quote Originally Posted by beanbag View Post
    My advice is based on working on shocks OTHER than Fox, but I would say:

    1) Set the IFP depth with the IFP valve OPEN. Use the recommended value or push the IFP down with the damping piston till it goes down as far as it would under full compression. (This would involve screwing on the main cap)
    MAIN CAP SCREWED ON 1st TIME
    2) CLOSE the IFP valve while at 0 PSI
    3) Fill with enough oil such that only a little bit will squirt out once you thread on the main cap.
    MAIN CAP SCREWED ON A 2ND TIME
    4) Put in piston and stroke it. Add or remove oil to fulfill step 3.
    5) Thread on the main cap with the piston slightly below the oil level.
    MAIN CAP SCREWED ON A 3RD TIME
    The bleed valve should be OPEN. Hold the cap steady with the bleed hole oriented upwards and rotate/screw on the main body. Some air and oil should squirt out the bleed hole.
    6) Your job is now to get all the air out of the oil chamber WITH THE PISTON IN THE NEARLY FULLY EXTENDED POSITION. With the bleed hole oriented in the highest position, compress the piston to push out air/oil or extend it to suck in more oil.
    7)CLOSE the bleed valve, but don't crank down on it too tightly. Push the piston down all the way.

    7a) If you feel a clunk before it bottoms, you've hit the IFP with the piston. You need to get more oil into the chamber. With the piston in the fully compressed position, OPEN the IFP valve. This air space will be slightly pressurized and a little air will come out. CLOSE the IFP valve. OPEN the bleed valve, and pull the piston outwards to suck in more oil.

    7b) If you feel too much progressive force as you push down the piston, you set the IFP too low. OPEN the bleed screw and push down on the piston to squirt out oil.

    8) Crank down the bleed screw all the way and pressurize the IFP.
    Your instructions make zero sense. You've screwed on the main cap 3 times?!?
    Also, you've never worked on a Fox shock. Heck, you sent yours to Push for service.
    So where does all your knowledge make itself relevant to a Fox shock?

  42. #42
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    Quote Originally Posted by HomegrownMN View Post
    Your instructions make zero sense. You've screwed on the main cap 3 times?!?
    Also, you've never worked on a Fox shock. Heck, you sent yours to Push for service.
    So where does all your knowledge make itself relevant to a Fox shock?
    no, it's twice if you don't have a number for the ifp, and once if you do.
    The instance in step 3 is an "as if".

    The rest of your reply is an ad hominum because you never address the trapped air issue. It's not exclusive to Fox shocks.

  43. #43
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    Quote Originally Posted by beanbag View Post
    The rest of your reply is an ad hominum because you never address the trapped air issue. It's not exclusive to Fox shocks.
    So enlighten me....How do you know there is air trapped inside?

  44. #44
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    Quote Originally Posted by HomegrownMN View Post
    So enlighten me....How do you know there is air trapped inside?
    read post 40 again.

    "Also, I recommend pumping the piston with the bleed screw closed and the ifp at 0 PSI but closed off to check for air bubbles. This check doesn't work if you inflate the ifp. "

  45. #45
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    Quote Originally Posted by beanbag View Post
    read post 40 again.

    "Also, I recommend pumping the piston with the bleed screw closed and the ifp at 0 PSI but closed off to check for air bubbles. This check doesn't work if you inflate the ifp. "
    I can read.

    I asked; how do YOU KNOW that there is air in the system?
    Bottom out? Poor performance? Too much travel? I have none of these symptoms.
    In fact if you read my posts, I exclaimed that the shock feels better than before. I have more control than before the rebuild with no ill effects.

    So again, how do you know there is air in the system? Because I didn't rebuild exactly how you would? Oh wait, you've never even done this before on a FOX rear shock.
    Maybe similar to other shocks, but not the same.

  46. #46
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    When you ask "how do you KNOW", do you mean how to check for, or how to prove that there is air inside your particular shock? In the latter case, the answer is "how should I know, I wasn't there to watch you."

    What I gave was a suggestion on best practices for minimizing trapped air, and a way to check if you got trapped air. It will take like a minute more time than doing it "your way" without the check. You can take it or leave it. Trapped air won't result in bottom out or too much travel, or even poor performance. It will show up as reduced oil life and a bit more hysteresis if you put the shock on the dynometer as the tiny bubbles expand and compress.

    The fact that your shock works better than before isn't saying much since it was busted initially.

  47. #47
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    Place the damper body into a soft-jaw vise and fill the body to the top with 10 wt. FOX Suspension Fluid.


    Push the bearing housing all the way down to the topout plate on the back side of the damper piston.

    Push the bearing housing downward into the oil, and wiggle it back and forth as you thread the bearing housing onto the body threads. This will help oil pass around the damper piston as it lowers into the damper body. As you thread the bearing housing onto the body, you will see oil flow out of the bleed port on top of the bearing housing; this is normal. If oil does not come out, you should unthread the bearing housing, top off the body with oil, and try again.


    Drop the steel ball into the bleed port and thread in the set screw. Tighten to 15 in-lbs (1.03 N-m).


    Install a new rubber pellet into the damper body. Using nitrogen, pressurize to 400 psi and torque the filler screw to 14 in-lbs. (0.97 N-m).


    This is straight from Fox.

    This is how I do it.

  48. #48
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    Hi
    Great thread.
    I have assemblied my RP 23 2009, 300 PSI in the IFP champer and new fresh oil. The air level is ca. 200 PSI (25% sag)
    But... My rebound is still not as it used to be. I use to have the rebound lver in the middle/ot 1 towards slow.
    Now an before I serviced it It need to be all the way to slow or maybe I gained 1 click after my service.

    Any ideas to get the rebound back.

  49. #49
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    Quote Originally Posted by HomegrownMN View Post
    Thank you, thank you, thank you!

    Great tip. Denver has the luck of having an amazing O-Ring supplier and they happened to have 2.5' of 7mm cord that wasn't 'in the system,' so I got it for free.
    I've got enough material for the next millenium!
    Couple question here guys;

    I'm ordering o-ring cord from these guy's: O-Ring Cord and Splicing Kits ( only one Stateside that I could find. Most seem UK based) Is there a particular duro and compound I need to ask for?

    Or if some of you want to make some $$ I would like to purchase, say 1 meter of this stuff... *cough* Homegrown

    Second question; I have a 7.875" x 2.0 " RP3 shock that I'm currently servicing. In the FOX literature there is no info on the IFP depth for this particular shock. There is however IFP depths for the RP23. I'm assuming the IFP depths would be the same - yes??

  50. #50
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    Quote Originally Posted by cort View Post
    Couple question here guys;

    I'm ordering o-ring cord from these guy's: O-Ring Cord and Splicing Kits ( only one Stateside that I could find. Most seem UK based) Is there a particular duro and compound I need to ask for?

    Or if some of you want to make some $$ I would like to purchase, say 1 meter of this stuff... *cough* Homegrown

    Second question; I have a 7.875" x 2.0 " RP3 shock that I'm currently servicing. In the FOX literature there is no info on the IFP depth for this particular shock. There is however IFP depths for the RP23. I'm assuming the IFP depths would be the same - yes??

    As for your last question, Yes. The IFP depth's didn't change between models, just between different length's/stoke's.

    I'd give you my O-Ring cord for shipping, as I no longer have this shock. But the O-RIng cord I have is not as perfect as I hoped. It doesn't "spring" back as well as I'd hoped for.
    You're welcome to it like I said for shipping. PM me if you want it.

    Joe

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