TAR-21 Gearbox Lockup Help

Discussion in 'Gun Building, Modifications & Repairs' started by Adrian_Grey, Jul 19, 2020.

  1. Adrian_Grey

    Adrian_Grey New Member

    I've been modding a Umarex/Elite Force TAR-21 for the past few months. I installed low-profile bushings (the gun had bearings), SHS 13.65:1 gears, an ASG Infinity Boost 30K RPM 16TPA Short Motor (high torque), a Raptors piston head, and a stock G&G piston. I also shimmed the gears, adjusted the motor, and did an AoE correction. I left in the wiring, cylinder, cylinder head, tappet plate, and nozzle.
    (I plan on replacing the wiring with 16awg wire and a Gate NanoASR mosfet, but that's another discussion.)

    When I put the gearbox back together, it won't fire, or it'll get stuck halfway and lock up, and then the wires and battery get hot and I have to disconnect them. This happened with the new piston/piston head I installed, and when I put the stock piston/piston head unit back in to test. Oddly enough, when I accidentally left out the piston and spring, the gears spin freely and move the tappet plate/nozzle.

    If any of you have any ideas on what might be causing this, I'd appreciate any advice/suggestions. I can provide pictures if necessary
  2. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    Have you tested to see if the piston with heads binds in the buttoned up mechbox alone with no other parts except cylinder and cylinder head? You can leave in the electrical components.

    Just so that you know. Parts are 80% not compatible unlike the old days where it was 80% compatible.

    This is what happens in an industry that has no standards and things are just cloned....the clones get more and more "fuzzy".