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  1. #1
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    Reba is locking out

    Howdy,

    I am about to service a RS Reba U-Turn Air MOCO damper. The fork compresses about 4mm and then locks out, even in the open position. When it is in the locked out position it does the same thing; it compresses 4mm and then locks out. I will service the fork completely. I just wanted to know what it causing this problem before I rebuild it. First of all I am guessing the oil level is low since the fork is not immediately locking out.
    Now, this may contradict my first guess, but my second guess is that the oil level is too high and the fork cannot achieve full travel. This is not highly probable since the u-turn air is working correctly as far as I can remember. My third guess it that the MOCO damper has failed.
    Any feedback would be appreciated.
    Thanks,
    Josué

  2. #2
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    Quote Originally Posted by Josue View Post
    Howdy,

    I am about to service a RS Reba U-Turn Air MOCO damper. The fork compresses about 4mm and then locks out, even in the open position. When it is in the locked out position it does the same thing; it compresses 4mm and then locks out. I will service the fork completely. I just wanted to know what it causing this problem before I rebuild it. First of all I am guessing the oil level is low since the fork is not immediately locking out.
    Now, this may contradict my first guess, but my second guess is that the oil level is too high and the fork cannot achieve full travel. This is not highly probable since the u-turn air is working correctly as far as I can remember. My third guess it that the MOCO damper has failed.
    Any feedback would be appreciated.
    Thanks,
    Josué
    Remove the lowers and see how much oil drains should be 16cc @ the most per leg. Pull the top cap and check the level - level should just touch the lower o-ring on the MoCo unit. You could do these steps in any order.

  3. #3
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    OK, I'll do that today if I get a chance.
    Do you think it could be oil migration? or what?

    I think that makes more sense.

    Ohh!! and I am just remembering something. (This fork was sent by a customer in another state.) One of the dust wipers was popped out when I took the fork out of the box. I suppose oil pressure due to oil migration or a bad service by a previous mechanic popped the seal out.
    What do you think?

  4. #4
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    Re: Reba is locking out

    Quote Originally Posted by Josue View Post
    .
    Do you think it could be oil migration? or what?
    Almost certainly.

    Remove the foot nut on the damper side, push the rebound rod up into the lower....I'll bet a bunch of oil comes out. If so you need a damper/rebound seal kit.

  5. #5
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    OK thanks,
    I'll check it out in the afternoon.

  6. #6
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    The only parts out of the damper/rebound service kit is the 12mm * 3.5mm O ring which sits inside the captive plastic stop at the bottom of the right leg. The wearing of this O ring is what allows the oil to migrate. I buy these O-rings (and the air spring 21 * 3.5mm O rings) in bags of 50 for around $5-$10 per bag.

    If you're going to make a habit of servicing RS forks, take the extra step and make up your own service kits - usually only the dynamic O rings need replacing (the ones that slide against another surface).

    - Joel
    Cycling is Serious Business.

  7. #7
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    There have been issues with the rebound rod seal head on some Rock Shox models over the years. You can switch the o-ring, as stated above, but a more permanent solution is to replace the whole seal head, which I think only costs about $12 or so. Plus it's easier to replace the entire seal head rather than dig that o-ring out and stuff another in.

  8. #8
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  9. #9
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    Quote Originally Posted by Matty F View Post
    There have been issues with the rebound rod seal head on some Rock Shox models over the years. You can switch the o-ring, as stated above, but a more permanent solution is to replace the whole seal head, which I think only costs about $12 or so. Plus it's easier to replace the entire seal head rather than dig that o-ring out and stuff another in.
    The whole seal head, regardless of which rebound unit you get, has the same O-ring in it. It's an expensive way of getting a new O-ring.

    - Joel
    Cycling is Serious Business.

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