Issues with V3 gearbox and m110 spring

Discussion in 'Gun Building, Modifications & Repairs' started by gregtotheizzo, Aug 1, 2012.

  1. gregtotheizzo

    gregtotheizzo New Member

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    Got a m110 spring to replace a stock spring on a umarex UMP. I swapped the spring and it was about a half inch longer than the stock. I've read this is natural and the spring will shrink once it's broken in. I put the screws back in, attached the battery and fired. It fired once (on semi), but when I fired again nothing...

    I put my stock spring back and fired...but nothing. I fire with out a spring and there's movement between the gears. I'm a totally n00b with only slight gearbox knowledge. I was told the gun could handle a m110 without a battery upgrade or motor upgrade. On the m120s and up higher batteries etc are needed.

    My guess is the piston was cheap plastic and broke.

    Anyone have any suggestions? The gears are metal. They move the thing that looks like a piston head which is right over the magwell. which leads me to believe the motor and gears work but the piston or teeth are shot.

    As I said total n00b but from research on this site and google it seems to be the case.

    Also is the length of the m110 an issue If it's longer than stock?

    Any help is greatly appreciated.

    Using an 8.4v 1200mah
     
  2. CoppertopNeasg

    CoppertopNeasg New Member

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    Does your gun make any sound when you shoot does the gun make any sound or is it completely silent? If it is silent one of your motor connectors may have come off or your fuse could have blown. If it is making a sound your shimming could be atrocious, you may not have a motor with enough torque or a big enough battery to pull a m120 and you set off your arl.
     

  3. GreenListerine

    GreenListerine New Member

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    ^this or
    Your battery is dead.
     
  4. gregtotheizzo

    gregtotheizzo New Member

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    Its only a m110 sprint. I think the piston is shot but I'm not daring enough to open the gearbox. Motor still spins as do the gears. I'm leaning towards piston teeth might be shot.

    The battery is not dead.
     
  5. Lefse

    Lefse Well-Known Member Supporting Member

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    Some M110 springs are closer to an M120, the manufacturers specify the spring strength a bit differently. The battery you are using is actually a very weak battery. Was it able to pull back the stock spring fine? Did you change the shimming or anything when you opened the gearbox, maybe the shimming is a bit tight. You pretty much have to open up the gearbox again to inspect all the parts and find out what's wrong.
     
  6. gregtotheizzo

    gregtotheizzo New Member

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    The umarex ump has a fast swap spring system. Slide the lower receiver off unscrew the screw and slide the spring out.

    The gearbox doesn't need to be opened for swapping springs.

    It's a madbull m110 spring
     
  7. Lefse

    Lefse Well-Known Member Supporting Member

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    I see, the motor and battery combination may simply be too weak to pull that spring then.
     
  8. philsaudio

    philsaudio New Member

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    Atlanta GA USA
    It is most likely the battery not having enough current output. Or the electrical system having high resistance somewhere. If it the battery furnished with the gun I would bet on it.

    Next upgrades could be Deans battery connectors, FET, rewire.

    If the battery will turn the motor when connected directly to the motor terminals it is the wiring or trigger switch.

    99% says it is the battery that is not up to the task.
     
  9. Lefse

    Lefse Well-Known Member Supporting Member

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    It is just a tiny ni-mh battery so it's not exactly a powerhouse. I agree with phil, a major overhaul is in order here. Throw that obsolete ni-mh battery in the garbage and invest in a 7.4v li-po and a balance charger.

    A Lonex or SHS motor would also be a nice upgrade. An SHS high torque or Lonex A1 should get the job extremely well in your setup, expect instant trigger response with those motors and a li-po.
     
  10. gregtotheizzo

    gregtotheizzo New Member

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    I'm saying it's not the battery because it pulled the spring back twice and then stopped. When I put the stock spring back in it won't pull that back anymore and the piston slides all the way back and I have to fire while sliding it back into place. I'm not sure if the piston head or piston is broken. Not being tech savvy I'm not sure if I should just send it back to umarex before cracking it open and voiding the warranty...

    However the battery was working and seemed to pull the spring back without ease. I'm not sure if the strength or length of the spring was to blame.

    I'm thinking about sending it in to airsoft gi for repairs and having them use a poly or aluminum piston and head. Any suggestions?
     
  11. gregtotheizzo

    gregtotheizzo New Member

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    Bump...

    Any thoughts on a piston/piston head? For v3 gearbox?

    Also should I keep using the m110 even though it's longer than the stock spring?
     
  12. Lefse

    Lefse Well-Known Member Supporting Member

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    Aftermarket springs are often longer than stock springs, so that's normal. I will recommend anything from Lonex or SHS really. If you want a super lightweight piston, a Lonex POM head on a swisscheesed Tokyo Marui piston is about as light as it gets.
     
  13. gregtotheizzo

    gregtotheizzo New Member

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    I'm not concerned about lightweight the gun is built lightweight. Abs plastic and only 3lbs. Shocked how durable it is...dropped multiple times. Just looking for something that'll handle the m110 spring.

    Should I keep using the madbull m110 and not be bothered by the length because it's normal?

    I think I'm going to attempt to fix myself and if I fail miserably send it in. I know ASGI does repairs. I live in jersey and the shops out here won't touch anything except an M4 or variation.

    Any other online shops that do repairs?
     
  14. Lefse

    Lefse Well-Known Member Supporting Member

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    You can learn how to fix it yourself, it's not rocket science. Just watch some tutorial videos on youtube to get a basic understanding of how to do it. Tech work is 80% patience really. The Madbull M110 is fine, you just need to do a basic gearbox tune-up. When I talk about lightweight pistons it's not to keep the total weight of the gun low, you won't notice the difference. A light weight piston is good if you're upgrading the rate of fire. The low weight makes it return forward faster, reducing the risk of premature engagement, it will also make life easier for the GB shell. If you open the gearbox, I'm sure you'll see how all the parts work together.

    I didn't understand how the cut-off lever worked before I opened my first gearbox. When I opened my first gearbox, I could see how it actually cuts the power to enable semi-auto fire, then it made perfect sense to me.
     
  15. chi-airsofter

    chi-airsofter Member

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    mokena
    Yes the lower the rate of a spring the longer the spring is. Can you take a pic of your piston?
     
  16. gregtotheizzo

    gregtotheizzo New Member

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    Lower receiver: how do I get the gb out lol
    http://i.imgur.com/YoyVR.jpg

    Piston: notice how far back
    http://i.imgur.com/4rgym.jpg

    Cross sectional view
    http://i.imgur.com/hfEHZ.jpg

    If I fire the piston shoots back(w/o the spring):
    http://i.imgur.com/WEpHR.jpg

    I have to dry fire to get the piston back in position to insert the spring. If I fire with the spring in and the piston back in normal position it slides back down to where I'm showing you how far down it is. I'm assuming the piston separated from the piston head...

    I'm not sure where the o ring part is (n00b) but my guess would be the spring pushed the piston head and the piston slid off the gears or the teeth broke.
     
  17. gregtotheizzo

    gregtotheizzo New Member

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    How do I get this motor out so I can get the gearbox out of the lower receiver.

    http://i.imgur.com/XWzpH.jpg

    I should mention I've been tugging and pulling on it but no luck
     
    Last edited: Aug 2, 2012
  18. chi-airsofter

    chi-airsofter Member

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    mokena
    Yeah it looks like you're the front of your piston broke off. Just buy a new piston and you should be fine. Maybe a piston head if it got damaged.
     
  19. chi-airsofter

    chi-airsofter Member

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    mokena
    Sorry Goethe double post ,but it's a motor cage. You have to take the grip off.
     
  20. gregtotheizzo

    gregtotheizzo New Member

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    If I pull the gearbox the motor pushes against the plastic grip...it seems I have to pull the motor out before I pull the gb out of the grip.

    Also it could slide out. Is there anything with the safety's I would have to pull them away from the gun and then slide gb out?

    I've seen videos where some slide out with the gear box and some need to be pulled out. I don't get how to slide the gb away from the grip...

    Also! Which would you prefer? Poly Carb or aluminum?