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  1. #1
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    Crunutt AIR XTD Shock losing pressure

    Hi fellow foes owners

    I've got a XCT 5 with 2.5" Curnutt XTD AIR shock, it has been ridden for one season (approx. 8 months of weekly ride).

    Until recently when the shock has been "broken-in" (very smooth now), but the Bottoming Control chamber has begun to fail to hold the air pressure. Typically, it will lose all its pressure after a day of off-road riding. It will also lose some pressure slowly if I leave it idle for a week.

    The Main Chamber is perfectly fine without any pressure leakage.

    Anyone met the same issue? any tip to repair it? Many thanks

  2. #2
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    emailed Foes Racing and got a super speedy response from them, I am advised to ship my shock over for an inspection.

  3. #3
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    the air shock went back to Foes for a rebuild, took less than 1 week to turn around.
    Just got it mounted back onto the frame, a test ride to be followed.

    Shox tech said I shouldnt ride with less than 50psi in the air chamber and no more riding when it leaks.
    guess I didnt notice it was leaking then kept on riding and causing damage.

    I'm happy with the Foes support team, they are very easy to deal with.

  4. #4
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    Quote Originally Posted by slickvic View Post
    the air shock went back to Foes for a rebuild, took less than 1 week to turn around.
    Just got it mounted back onto the frame, a test ride to be followed.

    Shox tech said I shouldnt ride with less than 50psi in the air chamber and no more riding when it leaks.
    guess I didnt notice it was leaking then kept on riding and causing damage.

    I'm happy with the Foes support team, they are very easy to deal with.
    Glad you got it taken care of. These shocks are relatively easy to work on. Look for my threadson the subject.
    Stupid, but sometimes witty. Occasionally brilliant. Slow and fat though.

    Specialized sucks dong

  5. #5
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    got lost in the forest for a while.

    the shock was good as new, but i have to do the "break in" process again. (not complaining)

  6. #6
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    I recently bought a 2:1 FXR and fully serviced 3" XTD Air. All good for the first few rides settling in and getting smoother. Then rode it in an enduro race the day following a quick few laps of the local bike park.
    Checked the pressures before the off, bottoming chamber had lost 5psi. The bottoming air chamber lost pressure early on the first climb, down to 50psi and shock sat at fully compressed, spring chamber was OK, but when unloaded returned to functioning correctly for 250m. This recurred several times on the climb. Re pressurised bottoming chamber and seemed OK but again lost pressure on a short uphill connecting stage. Repeated and rode short DH stage, no rough stuff, pressure held to end of the stage but lost again on connecting uphill. Tried to clear schraeder valve by pressuring and releasing air just incase dirt or lint had got into the valve core. Tentatively set out on next timed uphill, pressure held most of the way but the shock started to compress, dismounting allowed it to return and hold weight for the rest of the ride. At the end of the stage the pressure was again a little low. Re pressurised and set off on long DH stage, pressure held fine, checked at end of stage, all OK. Bottom out again de pressured on gentle uphill connecting stage. Again re pressured before DH stage, again pressure held until riding up hill on connecting stage. This recurred on the final uphill connecting stage. Again re pressurised before final long DH stage and pressure held to the end, it continues to hold now and appears to be 100% OK. The race day was hot by UK standards,27-28'C but not excessive,it is noticeable that the pressure is holding in the colder conditions since. Both dials were set at 1/2 way as per foes instructions on initial set up and air pressure set according to instructions also, for my weight: bottoming @65psi; spring@95psi.

    Any thoughts? I'm thinking most likely contamination of the valve core which was cleared by repeated pumping but that doesnt explain why the pressure holds on the DH sections when the shock is most active and depressures on the climbs when the platform is most in use.
    Could be just some random settling weirdness after a service and lengthy storage?Could air have got into somewhere it shouldnt have and then separated back out? Shock was serviced by the local importer(Balfa UK) and unused until i bought it, so i'm told.
    Baffled by this apparent weirdness, would expect the problem to get progressively worse and have to DNF with a mechanical to save the shock.
    Anyone have similar experience?
    Amazing performance when its working though!!

  7. #7
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    I had similar problems with a 'so i was told' "recently serviced, then unused since" XTD air from Balfa at the end of 2011 for a FXR 12x150 frame. Slightly different symtoms to yours. eventually the shock was replaced (this was after various other frame-related issues) and the new shock is tip-top 100% fine.
    i had serious doubts the original shock had been serviced - it seemed ever so unlikely it had been removed from the frame, e.g. fine, dried silt etc behind washers/nuts/bolts on shock mount - the stuff that you see in situ when you remove a shock after usage, but i cannot see how this would be 'put back in place' after a shock had been removed, serviced and refitted on a frame.
    After the shock was replaced and the other things in the end cleared up, I have only good things (very, very good things) to say about the frame, the shock and the ride. The initial teething problems were solved; at no cost but not inconsiderable delays and inconvenience. Now it's all sweetness and light.
    I'd suggest contacting Balfa and getting definitive advice on this. They told me mine might have suffered from having a seal fitted that somehow (i'm not sure how/why) 'rolled' (sort of inside-out?) and meant it'd compress and not return. Some suggestion that this *may* have had something to do with the shock sitting idle a while. Maybe iheart or katana (who have worked on these shocks) would be in a position to enlighten on this??...
    FWIW I've not over the yrs found that emailing Foes direct is particularly successful.

  8. #8
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    I would have serious doubts about it being serviced too. Shocks come back from TF squeaky clean...
    I could see that a seal with a feather edge may become stuck after long storage if the oil gums due to oxidation, then it would be possible for the edge to invert or be damaged. Are there any such seals in the bottom-out or are they all 'O' rings?
    That said i have seen 'O' rings which have stuck and then rolled rather than slide, its not usually very pretty and causes rapid failure. With a feather edge type seal I would expect this to cause an immediate and total failure. So bear in mind: I rode the bike for @ 30kms, starting on the recommended base settings and being gentle around Glentress bike park while getting a feel for it and adjusting the pressures. Then taking it out around the black loop at speed and making a few more adjustments, all at 5psi increments, before returning to the bike park and doing some more full on circuits of the jumps. No trouble at all during this, just appearing to bed in and get smoother, though the valving was becoming noisier, assumed as pressure was constant that this was normal(?). The unit was supplied squeaky clean and seemingly barely used, balfa sticker present.
    Going to contact Balfa about it and check the service histories of the 3 shocks i now have, one for DHS Mono as well. May service the DHS unit myself to see what gives. I think iHeart says the bottom out is the same on either the air or coil.

    I swapped the XTD Air for the coil unit which came with the frame and all is good.
    I completely agree about how good this frame is, best i have tried, the stability of the pedalling platform is amazing on either version, like riding a hardtail; suck on that "propedal"! And its also the first MTB frame i have ridden that just feels 'right', for me anyhow. :-)

    And FWIW none of the emails i have sent Foes has been replied to(about anything), it is a small outfit though, part of the reason i like them, but frustrating all the same.

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