Reba Extended to 120mm - Top Out Clunk- Mtbr.com
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  1. #1
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    Reba Extended to 120mm - Top Out Clunk

    I extended my Reba RL to 120mm on the Goblin and now I have some top out sounds. I can't remember if I had it before I made the changes or not. I only paid $27 for the 120mm air shaft for Reba/Sid, so if this doesn't end up working out its fine. I did NOT touch the damper side of the shock when I did the install. I just serviced the lowers, changed the air shaft and reinstalled/torqued everything to Rockshox manual specs.

    Do any of you have a clunk or thud feeling/sound when your shock tops out?. And when I say top out, I'm referring to when the shock is at its most extended travel. It does not happen when I'm going off a drop or over a jump, but if I'm pedaling on flat ground and shift my weight back and just slightly pick up the front wheel off the ground, I get a soft clunk.

    From my research, most forks are designed so that the damper shaft is longer then the air shaft, so when fully extended the top of the damper shaft does not make contact with the seal at the bottom of the shaft. With the 120mm air shaft installed, the air shaft and damper shaft are almost the exact same length at full extension. So I think my damper shaft may be topping out.

    Besides the clunk, shock feels great during compression, rebound adjustment works just fine in both directions and the extended length lets me run the shock at a lower psi now without bottoming out. The shock feels more plush at the lower PSI setting so I'm happy with that. I weigh around 190-195 geared up and with the Reba set at 100mm I would need about 130-135PSI to stop it from bottoming out on the trails I ride. Now with it extended, I can run it around 120-125 psi without it bottom out.

    Reba Extended to 120mm - Top Out Clunk-2015-01-18-20.19.52.jpg
    Attached Thumbnails Attached Thumbnails Reba Extended to 120mm - Top Out Clunk-2015-01-18-20.19.52.jpg  

    Last edited by TMO8853; 01-23-2015 at 08:51 AM.

  2. #2
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    I will preface this with the fact that I don't tear apart air forks on a regular basis. It sounds like there is a problem with the rebound damper. It might be the length or damage. That is where I would start my investigation. I do not know if the rebound damper needs an adjustment or replaced for longer travel. If I am incorrect, please correct me. As I said, I do not tear these things apart regularly but I have seen this topping out thud happen with bad rebound on other forks.

  3. #3
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    Quote Originally Posted by RSDSav View Post
    I will preface this with the fact that I don't tear apart air forks on a regular basis. It sounds like there is a problem with the rebound damper. It might be the length or damage. That is where I would start my investigation. I do not know if the rebound damper needs an adjustment or replaced for longer travel. If I am incorrect, please correct me. As I said, I do not tear these things apart regularly but I have seen this topping out thud happen with bad rebound on other forks.
    I guess I could put the 100mm air shaft back in and see if it goes away. If it goes away, we know the damper is ok.

  4. #4
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    You have piqued my curiosity on this one - I still have yet to do a fork service, but I am quite anal about cleaning my equipment after each ride. So far the oil is still clean, but I am pushing it. Let us know how this goes, as I didn't know you could get another 20mm on these forks, and it would be an option to convert while I tackle a service.

  5. #5
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    You likely didnt install the assembly in the correct order. There is a rubber top out bumper that goes on the air shaft and if its not placed correctly, it can cause a top out clunk. I suggest pulling it back apart and checking everything is installed correctly.

    It will not be a damper problem.

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