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  1. #1
    mtbr member
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    Enduro 5th Element Air Question

    I just purchased an end of season deal on an Enduro and after reading about all the issues with the 5th Element I am a little skitterish. Is there a really small volume of air in the IFP chamber? I am using my Fox pump that has worked fine on my 5th Element coil on my Bullit and when I go to put air in the IFP, as I unscrew it I hear the normal "pffft" of air escaping. Problem is, when I re-attach the pump, there is no pressure reading.

    So, I tried a few more times and then, with the pump unscrewed, I depress the IFP valve and either hear no air escaping, telling me all the air I had pumped in escaped when I unscrewed the pump, or I hear a very weak and short "pffft" leading me to one of 2 conclusions: there is air escaping when I unscrew the pump (from the IFP chamber) OR the IFP chamber just has a very small volume of air capacity to begin with. Visually it seems to me that the IFP is similar in size to the resi on the 5th Element coil so it might stand to reason that when I let the air out of either one that they would have similar durations of "pffft" but they don't.

    Incidentally, I don't have this problem with the other air valve on the shock, it reads pressure, albeit a bit lower, when I reattach it and the duration of hissing air is much longer than the IFP chamber, but that is a much higher volume of air, too, so I don't think it is the pump necessarily.

    Any thoughts? Sorry so wordy...
    "What do I know of You who spoke me into motion? Where have I even stood but along the shore of Your ocean?"

  2. #2
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    I run 100 psi in the IFP chamber and 140psi in the air spring, when I take the pump off and reattach it I usually get a IFP pressure reading of about 70-80 psi, so in other words it looses about 30psi when the pump is reattached. That figure probably varies with different pumps.

    I suppose if you were running minmum pressure (50psi?) it might be possible to get a near zero reading when you reattach your pump.

    Sounds a bit dodgy though I'd try and get another pump to check it with, maybe your pump is letting air escape when you take it off.

  3. #3
    mechmann_mtb
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    yes the volume in that chamber is very small. i usually expect a 20 psi drop when disconnecting, so i pump it up an extra 20 psi. i run mine at recommended setting (.5X rider weight) so mine is at 105 psi. i think my main chamber is around 125 or so (i actually havn't checked the pressure, the shock sags the same 25% since i did initial setup about 125 miles of sweet single track ago)

    don't worry about the shock. it should work fine. if you are really worried then save up some cash and switch to the Fox DHX, but i really don't think it is necessary. mine works great and i ride hard (205lbs no gear, 3' drops to flat etc)

  4. #4
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    With a properly functioning pump (they do wear out) there should be a ZERO psi pressure drop when disconnecting your pump. The pumps are designed to release the core BEFORE the rubber seal is broken between the pump head and the schrader housing. The only pressure drop you should see is from reattaching the pump, when air from the IFP chamber escapes into the hose and gauge of your pump.

    If you suspect your pump is bad, go to your LBS and try a brand new one and see if it works any better. Also, double check that your schrader core is flush to 1mm recessed in the housing.

    Happy riding!
    "I've come to believe that common sense is not that common" - Matt Timmerman

  5. #5
    Neo-Retro Forever
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    I had the exact same problem with mine...I just replaced the rear valve core with one from a punctured innertube I had laying around (one of the short-style shraeder valve cores), and it works perfectly now...give it a try.

    rb

  6. #6
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    The small air volume does make it more difficult. I had a problem with getting the psi correct and found out it was the pump by taking the pump to the LBS and testing. The new pump works better but the psi is hard to get right

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