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  1. #1
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    Can I user RS MoCo DNA damper?

    I ordered a MoCo Compression damper for a 2009/2010 Reba SL 26". In the picture below, you can see my old (the red one) and the DNA compression damper I recieved (even though it was not specified as DNA...).



    As you can see, the DNA damper is almost half the length of my original damper. I have ordered what I believed was the correct damper out of the description and picture twice, but recieved the DNA damper both times. The Parts Catalog only have the DNA damper.

    Can anyone confirm that I can use the DNA damper with the original rebound damper before I return this one too?

  2. #2
    Save Jesus
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    If it fits in the fork then use it. (You might need to add more oil)

  3. #3
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    I could, of course, but if I do I'm afraid I won't get my money back if I can't use it. As it costs over 90 bucks, I don't want to take any risks...

  4. #4
    Save Jesus
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    Don't use it then.

  5. #5
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    Thanks for the informative answer. I really appreciate it.

    Anyone actually got some experience with this?

  6. #6
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    There's a few things you need to check out.

    The moco dampers come in two different diameters (as well as a bunch of different lengths). There is only about a mm difference in dia but it is enough so they are not interchangeable. Measure the bottom diameter first where the lower o-ring is.

    If they are the same, then you've overcome the first hurdle.

    The second hurdle is that you will need to run a higher oil height / volume, and this may result in the fork hydro-locking before full travel is achieved or the higher volume may cause the fork to ramp up too much. You can test this out by reassembling the fork. Alternatively, you could use a measuring cylinder full of water and measure the displacement of each damper by immersing up to the threads. Subtract from this the total volume of the damper (Pi x r2 x h) to give you the "air" volume in the damper. If this is the same between the dampers then you're good to go.

    An alternative is to get the spare parts catalogue off the SRAM website and compare part numbers to see if they are compatible. The spare parts manual is good in that if a later part supercedes and earlier part you can cross check.

  7. #7
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    Thank you for an excellent answer!!

    The difference was not even a mm. It was 0.11 mm... :-) I guess that's good enough. The outer diameter at the o-ring was about the same on both, although measuring a rubber ring gives a certain margin of error.

    I don't think I have a measuring cylinder to measure the displacement thoroughly, so I guess I just have to try different amounts. This is the first time I'm disassembling a fork, so I am pretty much totally inexperienced. However, I'm a skilled aircraft mechanic, so I'm not completely lost when it comes to mechanical stuff. But how would you recommend me going forward to find the correct amount of oil?

    I've tried to use the parts catalogue, but not been able to find any notes regarding superseding parts.

  8. #8
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    If you want to fill the damper to the correct level it is a lot easier than mentioned. Measure your new MoCo top cap o-ring to bottom damper o-ring that will be the oil height measurment. Simply fill the fork so the oil is to this height when measured from the fork's top cap o-ring surface.

  9. #9
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    Quote Originally Posted by keen View Post
    If you want to fill the damper to the correct level...
    I'm not talking about getting the correct oil level, I'm talking about how to determine whether the newer damper will cause a hydraulic lock without actually installing the damper in the fork and getting it full of suspension oil and making it un-returnable.

    My method enables you to calculate the amount of air space in the two dampers. This air space is what gets filled by the oil displaced by the damper rod on compression.

    If there's the same air space (or if there's more air space in the new damper) in both dampers then it will work.

  10. #10
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    Quote Originally Posted by TigWorld View Post
    I'm not talking about getting the correct oil level, I'm talking about how to determine whether the newer damper will cause a hydraulic lock without actually installing the damper in the fork and getting it full of suspension oil and making it un-returnable.

    My method enables you to calculate the amount of air space in the two dampers. This air space is what gets filled by the oil displaced by the damper rod on compression.

    If there's the same air space (or if there's more air space in the new damper) in both dampers then it will work.
    Gotcha

  11. #11
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    Hers's a pic of a damper swap w/o any issues - just had to add more oil.


  12. #12
    "El Whatever"
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    It worked on my Pike... IIRC, the difference in oil volume for the two damper is in the order of 10cc's. Old Moco needed 125ml for a Pike, new BB as shown by keen takes 135cc's.

    Download the service manual for the two model years of the fork in question and see the difference in oil volume. The rest of the chassis/damper has changed very little over the year. The Reba also got this very same dampers.

    My Pike worked with the shorter damper, more oil and a longer shaft than designed (the Dual Rebound meant to be used on the Revelation 150mm). YMMV.
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