EEEEKK Help with AGM mp40 gearbox please!

The first part connects to the trigger linkage, and when rotated brings the electrical contact block forward to make a circuit. The second part is the anti-reversal latch and spring. It's sits at the back of the gearbox, and touches the bevel gear. It should be obvious where the spring sits to force the anti-reversal latch against the bevel gear.

Personally, I dont think you should have taken the gun apart if you dont know what something as simple as an anti-reversal latch is, and where it sits. I suggest that you dont try and re-shim the box - a job that needs to be 100% accurate.

When working on ANY AEG gearbox, ALWAYS disassemble it so that the components are sitting in the left hand shell. I.E. the air nozzle is pointing to the right.

all got to start somewhere. And I'd rather start on a chinese gun than a more expensive one. that way at least if I do a total bodge I dont need to worry.

I've read up plenty on shimming and understand the concept. its the other bits Im having to learn

I've just been fiddling while you posted that and have worked out some of that. just because I dont know its name doesnt mean I dont understand the concept.

In terms of the anti-reversal latch I've got that worked out now. just trying to work out which way the trigger linkage bit goes in. Should the bit that pushes the contacts together be the sloping side or the flat side of the top of the bit?

As for the spring thats with the trigger linkage bit it actually seems to belong actually on the plastic plate that lives beneath the cylinder. Returning it to place after its loaded a bb. even though it seems quite taught, but I suppose it has to be.

thanks for the help.

Okey dokey - Gearbox 101 incoming!

http://www.pegatiros.com/images/articulos/ampliacionnov05/ver3_1.jpg

Thats a standard V3 gearbox, as found in AK's, MP5K's and G36c's. The gearbox in the AGM MP40 is a modified V3.

That pic shows how you want the gears to be set up. With the stud of the sector gear (the one that engages the piston) at the 1 o'clock position. The A/R latch is just about visible behind the Bevel gear (the gear that meshes with the pinion gear on the motor)

Now, you see where the trigger is? replace that with the lump of monkey metal you have, with the small triangle of metal at the top. What happens is when you pull the trigger on the AGM MP40, the transfer bar will pull the bottom of the lump of monkey metal back, this will of course pivot on its axle, meaning the triangular bit at the top moves forward - if you have fitted it properly, it will push the contact switch together. It will be spring loaded, so when you release the trigger, it will push the contact switch apart.

The Tappet plate return spring should be strong. It's the last thing I fit before compressing the mainspring and closing the 'box.

Shimming, as you said you read up on it, I wont bother going into. Just take your time. And make bloody sure the bushings are sitting flat! (small piece of wooden dowling and a pin hammer are invaluable for this job)

thanks Kermit Its just a case of trial and error.

The first time I clasped it back together the contacts werent meeting. So took it apart again and rectified that. Now the motors spinning fine but when placed back into contact with the gearbox it cant move the gears so either a shim slipped or something else is out of place. It all went together pretty much as that diagram showed and without the spring in the gears span fine and the anti reversal latch was engaging the gear fine too. might be something not quite right with the piston perhaps.

A case of opening it up again tomorrow heh. but getting the hang of it and the help is muchly appreciated! let me know your preference of cider for churchills

Search ASCUK for info on gear timing & shiming, the anti reverse latch has a spring with it as well, also does the tappet plate, the gears need to be put into the other side of the box for assembley, I will post some pics, remember to use silicone grease on the piston seal & cylinder, & teflon molybendum or lithium grease on the gear teeth & bushings, I will take a few pics of the inside so you can see as I have on in bits in front of me now, but in all probability I doubt you will get it back together 1st time, it can be tricky

Ste.D

Pics:

thanks steve thats brilliantly helpful

does anyone know how to do the full auto mod properly, when i opened my gearbox, it exploded and now i cant fit the trigger extention bit in, what ive done is ive removed the selector plate and the spring from the selector gear??, its not like a normal V3, it doesnt have the same layout so im kinda stuck

I removed the plastic selector plate on the LHS, then removed the small metal peice withing the apeture at the front of the selector with a set of snipe nose pliers (it allows the repositioning of the gears for single shot, without it they just cycle) A bit brutal and don't let it fall inside , do it held upside down

The only downside is that once done you won't be able ot release the tension on the spring .....um.....so what ?........they are only

well mine went all day in the pouring rain at a skirmish this weekend as well as attracting a lot of "ooh cool a mp40 can i have a go" it shot 1500+ rounds without skipping a beat.

not bad for a gearbox newb :p

Good to hear

And whats the betting that whilst your AGM MP40 kept on ticking all day, there were numerous

3 x ca scar-l's
1x g&g l85
2x tm mp5's
and a couple of g36c's
lol they were dropping like flies

the very reason why i will get a clone thompson rather than the tm one even if it is plastic bodied

I removed the selector switch on mine so it is now full auto only. I then postioned the cut out on the cylinder so that it is visible when you take the top cover off the MP40 to insert or remove the battery. To release the spring tension after a skirmish, gently tap the trigger a few times and stop when the cylinder is in it's most rearward position(visible through the cylinder cut out)
Works for me
'shokt

Need help with my AGM MP40 too, its the gearbox that is the problem, and I need help determineing which parts go where!! Ill post a picture of the sections, parts I need help with, but as far as the main thing I need help with, is the part at the top right of the gear box where the thing that pokes out which I guess makes the bbs go through the barrell. Anyhelp would be great and I hope that I can get this thing fixed!!!

-Tobin

I did have some pictures of the inside but I aint got them now

but its basicaly a version 3 hybrid, the main diffrence is the motor is in a diffrent place & the trigger is mounted externaly on the mp40, heres some pics of the inside of a AK version 3 mechbox, these may give you an idea,

Thank you so much, that actually helps alot, but I had a question, Its gonna be a little hard to explain, but on the far left of the gearbox, does that little triangular piece with a small spring, is that supposed to be really tightly up against the bevel gear I think thats what it is called, and it is supposed to mesh with the pinion gear which is attached to the motor? So if I was too move the gear, it would only allow me to go one way. And also the white part which pushes the bbs on the other side of the gearbox, is that supposed to be srturdy within that white thing that kinda has a half circle so therefore it would be sticking out of the complete gearbox about like a half inch or something like that. Sorry if that last sentence doesnt really make sense, but I hope you can get an idea of what im talking about.

I cant realy see any triangular bits, I think you mean the anti reverse latch:

this mounts in the gearbox casing & engages only on the bevel gear, it stops the bevel gear turning backwards, the long white plastic thing is the tappet plate, this cylcles back & forth each full revolution of the gearbox it operates the air seal nozzle which feeds one bb at a time into the hop unit, it is driven by the sector gear,

Steve.D

Yess, that would be it!! Thank you, and also I had one last question. I got it to shoot regularly and all, but I took out the selector plate which makes it shoot fully, or semi, and now when I shoot it fully, it is kinda off beat.
Let me know if you can help me solve this problem. Thanks!!

Put the selector plate back in, people remove them & fill the hole to make it full auto only but I cant see the point, firing it on semi auto parks the piston in the fully home position ( hopefully) you cant do this on full auto, this saves your mainspring & piston teeth from leaving it part cocked in storage,

Steve.D