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  1. #1
    I work in .001 tolerances
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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
    I work in .001 tolerances
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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
    I work in .001 tolerances
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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
    I work in .001 tolerances
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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

  8. #8
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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
    I work in .001 tolerances
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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 Service 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!

  13. #13
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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.

  14. #14
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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
    I work in .001 tolerances
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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 Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  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 Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
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  19. #19
    I work in .001 tolerances
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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
    I work in .001 tolerances
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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
    arc
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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
    I work in .001 tolerances
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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
    moaaar shimz
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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
    moaaar shimz
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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?

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