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  1. #51
    PMK
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    Guys, I'll send Darren a PM to keep this post track straight.

    Scott, the checkvalves are not so much for low speed damping as they are to make the PP effective. The entire damper is a series of balanced circuits. With PP off, this negates for the most part the spring and micro spacer shims that preload the pop off valve. Selecting PP #2, will increase low speed damping noticeably. This indicates that the pop off spring is critical in rate and preload. With PP in full effect, yes the fluid is routed across the shims on the piston face, but also the flow could unseat the pop off valve if severe enough.

    There is a lot more going on than just the triangle valves and soft stack being the low speed. In my opinion, if you work the triangle valve shim stack to tune LS compression you may find the port area to small to give sufficient shim seat pressures and still remain controlled.

    You might find that changing the main piston shims to different aspect ratio of the stack to be more versatile in all phases.

    Ironically, often large ports are affiliated with HS damping, while ports to small can spike a damper, it is really flow volume over time. Additionally, the stack design, be it linear, preloaded, or digressive plays into this also.

    http://www.penskeshocks.com/files/TS...leedPiston.pdf

    When I have time I'll take some photos.

    PK

  2. #52
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    Thanks Darren.

    PMK, I get what you are saying. I think we were just saying it differently. I never stated that shimming the check valves was a valid way of drastically changing the damping. Just that it may have some effect.

  3. #53
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    Quote Originally Posted by PMK
    How much you looking to spend, when my loaner is returned I'll likely part with it since it is to short to be a spare on the ECDM.

    PK
    PM me when you get it back and we can discuss it. I'm very interested in getting such a shock for a reasonable price.

  4. #54
    PMK
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    Quote Originally Posted by Ola H.
    PM me when you get it back and we can discuss it. I'm very interested in getting such a shock for a reasonable price.
    I was hoping to have it already.

    PK

  5. #55
    cycle dad
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    Have any of you ever heard of anybody removing the nitro valve pellet retainer screw and putting in a valve stem to adjust the compression? I've heard the old float's valve stem threads in. Would this do anything?
    My rp23 hv with boost valve has no platform that is noticeable and I'm told it has something to do with this.

  6. #56
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    Quote Originally Posted by taletotell
    Have any of you ever heard of anybody removing the nitro valve pellet retainer screw and putting in a valve stem to adjust the compression? I've heard the old float's valve stem threads in. Would this do anything?
    My rp23 hv with boost valve has no platform that is noticeable and I'm told it has something to do with this.
    I did this on an old school fox RC with the piggyback, but I had to buy a special tap (5/16-32 I think). I had to use a fox schrader valve from an old destroyed float. I searched high and low for "non fox" schrader valves with suitable threads, but never had any luck. I've re-valved my RP-23 a couple times. I rigged a syringe from a gas chromatograph needle onto a shock pump that works really well. It's not all nitrogen, but I figure if plain air is good enough for a DHX, it will work for a RP23.


  7. #57
    PMK
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    Quote Originally Posted by taletotell
    Have any of you ever heard of anybody removing the nitro valve pellet retainer screw and putting in a valve stem to adjust the compression? I've heard the old float's valve stem threads in. Would this do anything?
    My rp23 hv with boost valve has no platform that is noticeable and I'm told it has something to do with this.

    It can be done but is a huge pain.

    From experience I know the internal pressure has a small window of decent performance. Additionally, every change is a compromise on some other parameter.

    Pull the air sleeve. Compress the shock, does it extend on its own. Keeping the shock so the rod is upright and at the top, does it extend smoothly on 6 or so consecutive cycles. If it bumps near full extension, the internals have air that should not be in there.

    Send it in for a rebuild, or follow this topic.

    PK

  8. #58
    cycle dad
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    It's a new rp23, less than 20 hrs on it probably. I sent it in anyway, but I am doubtful whether fox will do much. I think I'd need to have it pushed to my specific params. Maybe I should just look for a dhx air.

  9. #59
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    removing the shaft



    As we can see on the picture above, there is a tread at the top of the shock shaft. I believe that the shaft can be remove by using a thick rubber surrounding the shaft and turn it with a clamp.

  10. #60
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    Quote Originally Posted by Ola H.
    ...I thought I might as well give it a go

    So after a long winter filled with other things, I''ve started to work on this again. I managed to get the "upper head" unscrewed with the help of lots and lots of heat and some clamps a friend made. My neighbor helped me find replacement for each o-ring in the shock. Quite a bit of work and he's in the business. I replaced all o-rings and made a needle adaptor for my shock pump as well as a hex tool with a hole in it. However, I have not managed to pump it up and remove the needle without too much air escaping. I seem the rubber pellet is a bit damaged and my neighbor is looking for a replacement.

    However, I can pump the shock up and cycle it with the needle/pump attached. At first, it seems to work, but then you can see the tension go away from the lockout lever and a few strokes later the shock again starts to leak from the adjustment knob area. I reckon what happens is that the lockout rod inside the rebound rod is not pushed in hard enough by the air air pressure (aka nitro). So eventually, it slips out a bit and oil can flow past the o-ring. I reckon this was exactly the original problem too, rather than that the oring for the lockout rod was blown. When I got the shock, the lockout lever already had that sloppy feel, indicating that the lockout mechanism was not tensioned enough by the internal pressure of the shock. So in some sense, I'm on square one.

    I'm thinking of just plugging the rebound rod and not use the lockout since I don't like that anyway. I'll let you know.

  11. #61
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    Quote Originally Posted by Ola H.
    So after a long winter filled with other things, I''ve started to work on this again. I managed to get the "upper head" unscrewed with the help of lots and lots of heat and some clamps a friend made. My neighbor helped me find replacement for each o-ring in the shock. Quite a bit of work and he's in the business. I replaced all o-rings and made a needle adaptor for my shock pump as well as a hex tool with a hole in it. However, I have not managed to pump it up and remove the needle without too much air escaping. I seem the rubber pellet is a bit damaged and my neighbor is looking for a replacement.

    However, I can pump the shock up and cycle it with the needle/pump attached. At first, it seems to work, but then you can see the tension go away from the lockout lever and a few strokes later the shock again starts to leak from the adjustment knob area. I reckon what happens is that the lockout rod inside the rebound rod is not pushed in hard enough by the air air pressure (aka nitro). So eventually, it slips out a bit and oil can flow past the o-ring. I reckon this was exactly the original problem too, rather than that the oring for the lockout rod was blown. When I got the shock, the lockout lever already had that sloppy feel, indicating that the lockout mechanism was not tensioned enough by the internal pressure of the shock. So in some sense, I'm on square one.

    I'm thinking of just plugging the rebound rod and not use the lockout since I don't like that anyway. I'll let you know.
    Forgot to mention in my previous post. I dremeled a slot in a hex wrench to pass the shock needle into the septa with the wrench installed. This allows you to tighten the septa around the needle to prevent pressure from escaping during pressurizing the shock. you can still slide the needle out "with a little friction" without loosing any air. Then give the hex screw another half turn to permanently seal the IFP chamber.

    Hope this helps.

  12. #62
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    Quote Originally Posted by LAKESNAKE
    Forgot to mention in my previous post. I dremeled a slot in a hex wrench to pass the shock needle into the septa with the wrench installed. This allows you to tighten the septa around the needle to prevent pressure from escaping during pressurizing the shock. you can still slide the needle out "with a little friction" without loosing any air. Then give the hex screw another half turn to permanently seal the IFP chamber.

    Hope this helps.
    Yeah, I tried that but I think the little rubber pellet simply needs to be replaced since even with that trick pressure still escaped when taking the needle out.

  13. #63
    moaaar shimz
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    Updates?

  14. #64
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    I don't remember what my last update was, but I managed to find all o-rings and stuff and get the shock back together but the lockout (inner) rod still didn't seem to run OK. Possible it was me not being able to get the pressure in the shock up high enough, but after a few pumps of the shock, it started to leak oil from the adjuster again and the obvious reason was that the lockout rod kind of crept out fro its position.

    Since I wasn't gonna use the lockout anyway I simply plugged the damper rod an put together the shock without the lockout option (ie without the lockout rod). Now it seems to work but I've yet to put it on the bike since I bought another frame in in the mean time and don't have part to put the original Specialized back together. But the intention is to do it one day or the other and I'll report back. I'll try to post some pics of my syringe setup for pressurizing too.

  15. #65
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    OK, time for one more update. As mentioned earlier, I got another very nice frame so fixing this shock has not been a priority. But the other day I found some inspiration and built the good old Specialized up. As also mentioned, I had some problems getting the lockout mechanism leak free so I simply removed it and plugged the rebound shaft. Obviously, the right amount (=huge amount) of nitro (or air) pressure is very important for the lockout/platform mechanism to work and I in fact think that the problem from the very beginning was too little pressure here rather then a faulty o-ring.

    But anyway, while inside the damper I also shifter around some washers, placing one of the smaller ones between the first big ones. And with the bike put back together, the suspension now works very, very well. I didn''t get to ride it much in the original setup, but from what I remember the new tune is much more nice and active. I recon removing the lockout mechanism also allows more more undisturbed flow overall, ie even compared to then the lockout was in open mode.

    With my home made needle adaptor, I only manage to get around 80-100psi in the nitro chamber, but that seems to be enough, at least I have not experience problems so far. But I'm gonna test it on a really hard trail tomorrow, and we'll see.

  16. #66
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    So you've made it into a multistage shim stack?

    I look forward to your test results. If the nitrogen pressure isn't enough then the shock will suck air in on fast hits. The float on my wife's bike does this even with 300psi. Perhaps it's time to invest in some N2 regulators.
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

  17. #67
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    Quote Originally Posted by Dougal View Post
    So you've made it into a multistage shim stack?

    I look forward to your test results. If the nitrogen pressure isn't enough then the shock will suck air in on fast hits. The float on my wife's bike does this even with 300psi. Perhaps it's time to invest in some N2 regulators.
    Yeah, kind of multistage:ish, I reckon. In any case it worked remarkably well today. No leaks and no hissing sounds from air in the shock, not even after the pretty demanding ride (demanding on the shock). I now have a super smooth feel from the back end. 25-30% sag at 160 psi, super active with around 50% travel getting used even through some fine roots - providing a very cloud like feel. Then a smooth transition into maybe 80-90% of the travel which I get regularly when riding though rougher stuff. Finally each section of the trail I rode seemed to have one or a few hits that pretty much gave me full travel, but I still didn't feel any harsh bottom outs. Overall just very, very smooth, with no spikes either on sharp hits or more rolling stuff. The rebound adjuster works very well too with a range from mega fast to almost not moving back out at all.

    I don't have much to compare with, but for what it's worth, the suspension action now complements the bike perfectly for the type of trails I ride.

  18. #68
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    Quote Originally Posted by Ola H. View Post
    OK, time for one more update. As mentioned earlier, I got another very nice frame so fixing this shock has not been a priority. But the other day I found some inspiration and built the good old Specialized up. As also mentioned, I had some problems getting the lockout mechanism leak free so I simply removed it and plugged the rebound shaft. Obviously, the right amount (=huge amount) of nitro (or air) pressure is very important for the lockout/platform mechanism to work and I in fact think that the problem from the very beginning was too little pressure here rather then a faulty o-ring.

    But anyway, while inside the damper I also shifter around some washers, placing one of the smaller ones between the first big ones. And with the bike put back together, the suspension now works very, very well. I didn''t get to ride it much in the original setup, but from what I remember the new tune is much more nice and active. I recon removing the lockout mechanism also allows more more undisturbed flow overall, ie even compared to then the lockout was in open mode.

    With my home made needle adaptor, I only manage to get around 80-100psi in the nitro chamber, but that seems to be enough, at least I have not experience problems so far. But I'm gonna test it on a really hard trail tomorrow, and we'll see.
    Hi there, great thread!

    I have a faulty rp2 that seems to have no rebound and no lockout at all, keeps air pressure correctly though.
    Me too, have found oil leaking around the rebound knob and diagnosticated a faulty o-ring but since I read that it could simply be a matter of the lockout rod moving by means of low or no n2 pressure, and maybe this low or no pressure is keeping oil away from the damping piston?
    I´m wondering if adding pressure to that ifp chamber could fix the problem?
    could it be that easy?
    maybe just pump it up?
    I read that you use a needle valve to pump air through the round disc below that allen screw at the bottom of the shock, and seems some of you have tried to put a schraeder valve there. how much pressure?
    maybe a picture of this rubber disc and allen screw undone? it is difficult for me to imagine how to charge the shock...
    BTW how much oil and sae does this shock run in 200 x 50 lenght and stroke?
    thanks guys I really appreciate the effort behind all this thread!

  19. #69
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    Hi Ola H.
    since I can not Pm I´ll try and contact you here.

    first thanks ALL of you for your thread, is very interesting.
    I seem to have a problem with my rp2 that you´re familiar with. leaking oil through the rebound knob and no lockout or rebound regulation.
    could it be just a matter pumping air into ifp?
    I just miss the part of replacing those o-rings in your thread to give you an applause ha ha ha
    do you think its a must to replace these o-rings or any other simpler solution?

  20. #70
    moaaar shimz
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    If you lost some oil it's time for a full rebuild. No simpler solution.

  21. #71
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    so that brings the second question up:
    how much and sae oil? heard its sae 10 but dont know how many cc´s or oil height ofr a 7,875 x 2 rp2
    thanks for your quick reply tacubaya gracias señor

  22. #72
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    Shock is dissasembled. Just need to take apart the shaft to replace those hidden o rings. Need help with ifp depth and pressure and oil quantity and sae. Dont want to build a hidraulic pump hahaha.
    Btw will try to replace that stupid rubber disc with a schraeder valve.

  23. #73
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    Quote Originally Posted by Scotth72 View Post
    Here are the pics I promised.











    This is an older RP3, 2005ish. It had a preloaded high speed comp stack. but like I said, that is now in another shock.
    in the exploded view you have excluded the star shaped first washer. does it stay fixed or does it move freely?

  24. #74
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    Quote Originally Posted by Dougal View Post
    To unscrew the shaft without damaging it you can make a shaft clamp from a piece of aluminium or other soft metal.
    Drill a hole through as close as you can to the size of the shaft and then saw a slot through it. Use these in the vice to get enough grip without damage.

    Alternately, you can try wrapping a piece of inner tube around the shaft so it grips your wooden blocks better.
    I needed some heat to get mine of be gentle though.

  25. #75
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    IFP debth and Oil:
    Press the IFP floating piston down as the shaft pushes it down, when you screw the bearing on the body.
    Unscrew the bearing again and give the IFP piston a small notch (1 or 2 millimeters)
    And you will be fine..
    NOW close the Nit. valve so you cant move the IFP piton down more.
    fill it with oil and screw the bearing back. try and get as little (NO AIR) in the body together with the oil.
    See the rock shox video here:
    RockShox Monarch Rebuild - YouTube



    I think the models 2008 and up uses 300/400 PSI Nit. or "air"
    Oil 10wt (but again is a broad term) stick with the known manufacturers)
    No guaranties guarantied
    Last edited by SteelKof; 01-15-2012 at 07:20 AM.

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