M4 Motor Issue

[hot_shot under fire]

Hey everyone,

I recently did my first gun doctoring job on my King Arms M4 AEG. It initially started as simply replacing the cut-off lever but that quickly turned into installing new trigger contacts, some new wiring, motor connectors and Deans connectors, PLUS purchasing a new motor. After I put the gearbox back together I hooked up my brand new Lonex A5 motor and a 9.6v 1600mah battery to insure my wiring job actually worked. Luckily everything looked to be functioning properly, so I put the gun back together.

Now, here's where the issue started...

After installing the grip and putting the motor inside I went to adjust my motor height. When I went to squeeze the trigger, to my astonishment nothing happened. Not so much as a mechanical whir from the motor was made. I took the motor out, squeezed the trigger and everything ran just fine. So, after adjusting the motor height down thinking the gearbox was just jamming up I put the motor back in, and again nothing happened.

After some tinkering around, I found out that when the motor plate is screwed down I'm getting absolutely no electrical contact. But, if I undo the motor plate screws and allow the motor plate to come about half way out of the grip, everything works just fine.

Does anybody know what is causing this? And if so, is there a fix for this issue?

Thanks in advance,

Jake

[Stealth]

Are your motor connectors completely heat-shrinked?

I suspect that your connectors are loose so when you push down on the motor, at least one of the connectors are popping loose. Try clamping them to they are tighter on the motor posts.

[ThunderCactus]

Did you mess with the shimming at all? Your bevel gear may be shimmed too close to the motor causing it to jam up no matter where it's adjusted when the end plate is on.

One thing you can try is testing the height by hand, you can actually pout your thumb on the end of the motor and push it up into the grip yourself and try shooting the gun. There isn't much back pressure at all when it's running.
If your can push the motor right up to the gears and the mechbox cycles, then you most likely need to reshim the bevel gear, unless somehow your motor connectors are arcing right through the end plate.

[hot_shot under fire]

Thanks for the quick replies!

I assumed one of those 2 options was the issue, I just wasn't too sure whether my limited 'Airsoft Mechanics' knowledge was sufficient enough to diagnose the issue, so I came here to be safe.

I attempted to push the motor down with my thumb and the mechbox cycled without an issue. After putting the motor plate on again it wouldn't cycle. The issue MAY be that my positive motor connector is disconnecting when I put the motor plate on, although I don't think that is the issue.

As far as the shimming goes, I didn't touch the shimming in the gearbox. If I recall correctly I put all of the shims back where they came from (As they came off with the gears when I pulled the gears out)

Perhaps I should take the M4 to a proper gun doc and get this issue resolved.

[ThunderCactus]

The new motor might be getting hung up on the end plate too. If it's got one of those really wide screws, take it out and put the end plate on, see where the motor is sitting.
There should be a very noticeable amount of up/down play in the motor height if you poke it with a pen while the end plates still on.

[hot_shot under fire]

Well, right there seems to be the issue! My motor isn't centred in the grip properly so it's getting caught on the motor plate and pushed down as far as it can be, thus (as far as I can tell) binding the gears so nothing moves, thus explaining the lack of response when I squeeze the trigger...

I'll see what happens after I fiddle around with the motor and see if I can get it to mesh with the motor plate correctly.

Thanks!!

[Stealth]

Part of the reason you're getting this issue is that the wires are routed in a way that'll angle the motor.

An easy way to check this is to remove the motor height adjustment screw entirely while installing the motor plate and observe the motor end bell in relation to the now-exposed hole.
Wires should look kind of like this (observe that the wires are angled instead of parallel to the endbell). Ignore washer.

[ThunderCactus]

Ah yeah forgot that bit. Make sure both wires are routed through the back of the grip

[Alanh]

Ive got a similar issue, though mine grinds as well, ill try some of whats mentioned

[hot_shot under fire]

Stealth:

I got my order in from you guys so I can get my M4 up and running hopefully for Art of War (Lightning fast shipping as always, DEFIANTLY going to put another order in ASAFP!)...

Quick question before I close my gearbox up though. When I run the positive motor connector wire to the motor, should I run it through the gearbox's wire channel to the same side as the negative wire and run the positive and negative wires through the same hole to the grip/motor compartment? Or should I run the positive motor connector wire through the other hole, then run the wire inside of the grip to the same side as the negative wire?

[Stealth]

Originally Posted by hot_shot under fire

Stealth:

I got my order in from you guys so I can get my M4 up and running hopefully for Art of War (Lightning fast shipping as always, DEFIANTLY going to put another order in ASAFP!)...

Quick question before I close my gearbox up though. When I run the positive motor connector wire to the motor, should I run it through the gearbox's wire channel to the same side as the negative wire and run the positive and negative wires through the same hole to the grip/motor compartment? Or should I run the positive motor connector wire through the other hole, then run the wire inside of the grip to the same side as the negative wire?

Unless you have done the mod outlined in this Airsoft motor misalignment fix part2 : m4 style grip & gearbox modification for low gauge wiring - YouTube, the red and black wires should be coming out of their respective holes in the mechbox. Then they should go through the two holes in the grip.

Once inside the grip, you will need to make two 90 degree bends to bring the red wire to the same side as the black wire. Make sure the red wire runs along the edge of the grip and doesn't interfere with the motor shaft. Both wires should run up the same side inside the grip (ie rear of gun side). If you were looking top down with the gun stock jabbing into your stomach, the black wire should be run left of the screw hole, and the red wire should be run to the right of the screw hole.

Once both wires are out, put your motor into the grip. Make sure that it is "springy". Attach the two motor leads as shown in the picture above.