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  1. #1
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    Why does my Lefty DLR2 blow & suck (air) ??

    My just rebuildt Lefty has developed the following symptom .
    After I pump up the air pressure in it with my shock pump ,
    upon undoing the pump , it releases all or the air ( not the usual
    5# or so) . It doesn' t matter how fast I undo the pump , it all comes
    out .
    As soon as this air gets out , the Lefty then sucks itself up (compression) .
    Sounds like "negitive air pressure syndrom "
    Easiest fix would seem to be to replace the schrader valve but I have put 4 different
    ones in there and it doesn't help .
    Mendon was the one who did the rebuild but is out of town so is at the moment
    unable to assist me so while my Rush sits in my repair stand begging me to take
    her riding , I'd thought I'd through my question/delema out to the board and see if
    anyone might have an idea what is wrong .
    I have upgraded to the double o-ring air piston with the rebuild .

    HELP !!!!!!!
    Last edited by ccaddy; 09-30-2007 at 08:20 PM.

  2. #2
    Are you talking to me?
    Reputation: damion's Avatar
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    Can you try a different shock pump?

    They all have different release points, so you may try that.
    gfy

  3. #3
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    Can't be the pump , this is the same one I've used since day one .
    Even if it was responsible for the loss of all air , how do you explain
    the Lefty "sucking" upward after all the air is released

  4. #4
    Kam
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    Quote Originally Posted by ccaddy
    Can't be the pump , this is the same one I've used since day one .
    Even if it was responsible for the loss of all air , how do you explain
    the Lefty "sucking" upward after all the air is released
    i am not sure what is with the air loss on you dlr2, but your fork is "sucking upward" because of the negative coil spring in the fork. i am pretty sure that is normal.

    when you fork is aired up the fork should lengthen to it's max length. when the fork is de-pressurized the fork will sag. it is normal.
    Last edited by Kam; 10-02-2007 at 12:38 AM.
    "forget kings...forget hadleys......they all have crap engagement. just run your bike fixed gear." - FoShizzle

  5. #5
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    By sucking upward , I mean it is completely compressing to zero travel .
    This is by no means normal .

  6. #6
    Kanonkuglen.dk
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    Sounds like....

    You just need a new valve... I had the same symptom, changed the valve and no problem:-)! You just take the valve from a bike innertube with a car valve:-)!
    Got the Cannondale fewer - my cycling blog: kanonkuglen.blogspot.com

  7. #7
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    I wish it were that simple but as per the original post , I've
    replaced the valve core 4 times with out any luck

  8. #8
    Kam
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    Quote Originally Posted by ccaddy
    By sucking upward , I mean it is completely compressing to zero travel .
    This is by no means normal .
    actually, my speed 110 carbon dlr2 also does that too. when there is no air in the fork, the fork totally compress so there is no travel in the fork at all.and i do not think there is anything wrong with my fork either. it feels great when riding.

    have a friend that has a shock pump you can borrow? sorry to bring it up again, but if this doesn't happen with a second pump then you can be riding asap with only $20 down the drain. with mendon swaping to the newer piston/seal and your changing the valve a few times, i really think the culprit is your pump.

    good luck.
    "forget kings...forget hadleys......they all have crap engagement. just run your bike fixed gear." - FoShizzle

  9. #9
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    I'm not too familiar with your shock but actually it's normal for the shock to "suck in" .
    Almost all high performance car shocks do that.

    Look at the oil chamber in your shock as a closed container....when you compress the shock the stanchion tube increases the volume inside the oil chamber and will probably stop half way since there would not be enough room inside that shock.

    In order to make sure that the stanchion tube can completely slide in there's a trick when you change the oil: You fill the damper with oil, then slowly compress the shock all the way and then seal it. When you pull on the shock now it'll create a void in the oil chamber resulting in a vacuum. That's why it pulls in. If you don't use that particular procedure the shock would only be able to compress half way and you'd have limited suspension travel.

    That's how the "Bottom out control" on a SPV system works. By slowly turning clockwise the SPC air bladder is forced inside the oil chamber taking up space were you can't compress the shock all the way anymore.

    As far as your valve goes: try to shorten the valve core a tiny bit. Just file the tip of or something. That way it'll close before you completely disconnect the pump.
    Worked fine on my old fatty I had on my Super Vee.
    (I also cut down the little metal thingy on my pump that opens the valve when you screw it on.)

    Hope this helped.
    "Common sense isn't always that common!"
    Custom Prophet and Custom Delta V

  10. #10
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    The puzzling thing is that the Lefty (which is a fork , not a "shock" ) has never
    compressed after removing the shock pump before .
    I too was thinking it may be my pump but the fact that before the compression
    issue , the Lefty was having problems holding air (even after upgrading to the dual o-ring air piston) during rides has led to the
    diagnosis of replacing the Lefty's lower (warranty) , thanks Mendon
    Last edited by ccaddy; 10-07-2007 at 08:26 AM.

  11. #11
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    Well okay. I always call the "Damper assembly" or "Cartridge" a shock...my bad.
    Also like I said I'm not too familiar with your particular shock eh... fork and didn't know that the oilchamber inside your shock....Xcuse me "Damper" assembly is separated from the air chamber with a war. If that thing got stuck or warped it makes sense.
    "Common sense isn't always that common!"
    Custom Prophet and Custom Delta V

  12. #12
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    How old is the pump? I had an issue where air leaked out big time with my old pump. turned out the connection on the pump was just worn out. So I bought a new pump, and everything was fine

  13. #13
    mad aussie
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    I find this happens to me usually because the schrader valve is not threaded in far enough. I have to keep tightening it a turn at a time and checking to see if the air will stay in when the pump is unthreaded. Just dont do what I did and thread it in too hard or the fork may develop a leak if the schrader valve gives.

    I found this to occur more commonly if you are using a "black" schrader instead of a red one from Cannondale for some reason although they look the same???

    Kevin

  14. #14
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    Black ones are all you seem to be able to get from auto parts stores .
    I'll have to see what the LBS stocks .

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