AK spring compression distance and upgrades

Discussion in 'Gun Building, Modifications & Repairs' started by Dedshaut, Feb 10, 2018.

  1. Dedshaut

    Dedshaut New Member

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    Rio Rancho
    so I thought I would upgrade my son's cm028 by correcting AOE using sorbo, adding a steel guide rod with bearings, replacing the piston since it was worn, and shimming gears. Long story short, between the sorbo and guide rod bearing, the spring fully compresses before the sector can rotate enough to release the piston. This locks up the gearbox. Has anyone run into this? What can I do to resolve it while keeping the upgrades? Cut the spring maybe?
     
  2. Hangtight

    Hangtight Well-Known Member

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    Where did you fit the sorbo? If you're using the stock spring and all you've done is add a bearing spring guide they're no way the spring should get coil bound.
     

  3. Dedshaut

    Dedshaut New Member

    13
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    Rio Rancho
    I glued the sorbo to the cylinder head. I've performed these upgrades to other AEG's without issue.
     
  4. Hangtight

    Hangtight Well-Known Member

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    Are you sure it's the spring? The other possibility is that the piston is hitting the rear of the gearbox. I've also had occasions when part of the piston is catching on edges in the gearbox. I'd suggest fitting just the cylinder, piston and sector gear to the gearbox, screwing it shut and checking that the sector can move the piston and release it without hanging up anywhere.
     
  5. Dedshaut

    Dedshaut New Member

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    Rio Rancho
    When i remove the sorbo and use the stock spring guide the gun runs fine.
     
  6. Hangtight

    Hangtight Well-Known Member

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    How much have you taken off the piston teeth for the AOE correction?
     
  7. Hangtight

    Hangtight Well-Known Member

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    And how thick is the sorbo?
     
  8. Dedshaut

    Dedshaut New Member

    13
    4
    Rio Rancho
    Sorbo is 3/16, one and a half teeth removed for AOE. After thinking about it more, I think the bearings on the guide rod may be too wide and I might have to sand the inside of the end of the cylinder to prevent it from binding. I used 2 different pistons, and both had the same result, maybe if I just slightly bevel the opening this would cause the piston to self align easier over the bearing. The bearing does fit in the piston, but there is little clearance.
     
  9. adas1223

    adas1223 Active Member

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    stratford
    looks like a combo of the THICK sorbo + THICK guide rod. Yet you want to keep these mods? take a tooth off of the sector gear. OR you could sand the piston or rod OR cut the spring. the choice is yours!
     
  10. Guges Mk3

    Guges Mk3 Well-Known Member

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    Minneapolis
    You don't need a bearing spring guide. If you have a washer on it, that is sufficient. The Bearing system is a legacy solution to a problem that no longer exists.

    Just ditch it.