RC4 wont hold air...

Discussion in 'Downhill & Freeride' started by BikerBoy28, Apr 13, 2011.

  1. BikerBoy28

    BikerBoy28 Monkey

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    So after a great weekend of riding/racing at the PRGT, I find that my RC4 air chamber is empty (yesterday). Ok weird, fill it up to 175psi and pedal it around and it feels normal. Just headed out to the garage to find it empty again. Pumped it to about 175 and it feels normal. I dont see any signs of it being blown, no oil or anything so I'm not sure whats going on. Did a lil research and nothin came up. Any of you suspension guys know whats wrong here?
     

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  2. demo 9

    demo 9 Turbo Monkey

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    At the risk of stating the obvious, its probably a slow leak out of the valve. Try tightening it?
     
  3. NoUseForAName

    NoUseForAName Monkey

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    +1

    @D9: You are on form for helpful info right now.
     
  4. tuumbaq

    tuumbaq Monkey

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    Interesting . . . First thing I'd say is, are you 100% the chamber IS in fact empty ?

    My reasoning behind this is if was indeed empty , YOU WOULD notice it on the trail...for sure.

    You need a minimum air pressure in there in order to keep things working, properly .Without enough air to "hold back " the pressure coming from the oil on that valve, oil would migrate into the air chamber and your shock would feel like poop.

    First thing that comes to mind is your presta valve might be broken and you just can get a proper reading on your pump...OR your pump is faulty.That would be my first guess.Try pumping air in there and depress the presta valve with a sharp tool (do not cycle the chamber once its empty).You should hear a clear hissing sound, If nothing comes out of there and everything "feels" normal...well Im not too sure what up with your shock bro.
     
  5. demo 9

    demo 9 Turbo Monkey

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    not sure if thats sarcasm.

    going a bit further, i would be surprised if it actually went to ZERO psi, even a ****ty tube valve will hold 15 psi. which upon compression might keep the oil "held back"

    The shock might be empty (or close to it) but that 15PSI might still be enough to function which is why you may not have noticed it when you were riding.

    My vote still goes towards tightening the valve.
     
  6. p-spec

    p-spec Turbo Monkey

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    If it actually leaked out down the driveway,after just pumping it,I'd call fox for servicing.

    How old is it ( just curious,not that I have an answer for you ).***
     
  7. BikerBoy28

    BikerBoy28 Monkey

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    It did have air in it during the weekend, I know that for sure, its just when I got home and cleaned my bike the next day it was empty. My shock pump is almost new and seems to be working fine, I can pump up the chamber, take the pump off, put it back on and it reads correctly. Ill try yours and demo9's advice and see how that works.
     
  8. BikerBoy28

    BikerBoy28 Monkey

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    No it leaked out overnight. I believe its a 2010, it came on the used frame I bought.
     
  9. BikerBoy28

    BikerBoy28 Monkey

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    Okay so I just filled the chamber to 200 and upon removing the pump there was a high pitch squeal and all the air emptied. Filled it back up and now there is an audible leak from the stem
     
  10. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    It's really easy to replace those valve core stems, there is either a proper valve core remover tool, or you can use really small pliers.

    You can replace it with one from another shock's valve, or even a schrader tube for now to diagnose the problem.
     
  11. NoUseForAName

    NoUseForAName Monkey

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    Not sarcasm.
     
  12. kidwoo

    kidwoo Celebrating No-Pants Day

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    This^ Just got to an auto parts store and buy some cores and a core tool. If you're really paranoid, wrap a little teflon tape around the threads before putting it in.


    Should run you a whopping 3 bucks.