Motor alignment / battery strain question

[Quibble]

Hi all,

I have a JG M4 Stubby that I recently upgraded with a new piston (after much agro), piston head, fresh wiring and connectors. I’m a bit worried about the alignment of the motor and pinion gear. If they are over meshed, will it simply not fire or is there a chance that it will but put unnecessary stress on the motor and battery? I only ask because the battery I’m using doesn’t seem to last as long as before. I have discharged it properly and slow charged it a few times... it's a fairly new battery too. The rate of fire has increased somewhat so I assume this will drain the battery a little quicker, as the gearbox is cycling faster per burst of fire. Is that a correct assumption? Here’s what I did to adjust the motor alignment:

There are two main screws at the bottom of the grip that hold the plate / motor in place. When I tighten those up fully, the gearbox does nothing. I just hear a faint click as if it’s trying to cycle. I assume this means the gears are over-meshed. So I untightened the motor height screw that is in the middle of the grip, as advised by other guides online but that didn’t do anything. So I screwed it back into the position it was in before and adjusted the other grip screws instead. Eventually the gearbox whirred into action…

Should that be ok? The motor moves around freely when wired up and the grip plate is off but it is a little tough to put on and push up… is that normal?

Sorry for the wall of text lol but any options and advice would be gratefully received.

Thanks!

[Crude Skinny B]

Re: Motor alignment / battery strain question

when replacing the piston did you:

A: re shim the gears (correctly)
B: do nothing and just put it back together

To me it sounds as if the bevel gear is to high.

[Quibble]

Re: Motor alignment / battery strain question

Thanks for the reply.

I took time to carefully re shim the gears with new shims so they turned easily once the top of the gearbox was screwed back on. I had a very thin shim on the bottom of the bevel gear because if left the bevel gear un shimmed, it looked too close to the bottom of the gearbox imho. I checked all the gears several times and they looked like they were meshing just fine without the gear surfaces touching or the gears moving up and down.

I suppose it's possible that its a shimming issue but I have worked on other gearboxes before with no problems and I took my time with this one too...

Perhaps I should have just left it alone lol

[Crude Skinny B]

Re: Motor alignment / battery strain question

did you shim the bevel gear to the pinion gear first?
like this (scroll down a little)
http://ftp.airsofttutorials.com/cent..._Shimming.html

[Quibble]

Re: Motor alignment / battery strain question

That is an awesome guide! Many thanks for the link.

I'm going to have to take it apart again and check just to make sure otherwise it's gonna bug the hellouta me! Sigh...

As I said the gun is working and I think the alignment is ok but there is a slight whine every time it fires. Is that normal?

[Crude Skinny B]

Re: Motor alignment / battery strain question

whining is usually when either the motor is to tight against the bevel or the gears are not shimmed correctly, maybe the motor doesn't have enough torque? but i wouldn't though that that was the case

[Quibble]

Re: Motor alignment / battery strain question

Ok well I'm pretty sure I shimmed the gears properly. I screwed the gearbox together with just the shimmed gears inside and turned them with my fingers. They felt loose and were able to spin freely. I only put one thin shim under the bevel gear because it looked too close to the surface of the gearbox without one... also the gears had little if any vertical play when pushing them up and down.

The motor and spring are stock and the rate of fire is better than before due to the new wiring, connectors and one less tooth on the piston (AOE correction) so I guess it's working fine. Surely the gearbox is supposed to whine a little bit, what with the motor and everything going on?

[EBR-freak]

Re: Motor alignment / battery strain question

look... the best prooven way do the motor height and shim the bevel gear is as follows...
a. remove everything from the gear box. move the top half of the gearbox to one side as we wont need it for a while.

b. place the bevel gear and its bearing into the bottom half of the gear box. now without moving your bevel gear screw on the pistol grip to the bottom half of the gearbox (still no top half of the box).#

c. place the motor and motor plate inside the pistol grip and screw the plate on. you will nnow be able to see how the pinion gear meets the bevel and will be able to correct and fine tune the AOE and shims on the bevel.

once you have got the shimms for the bevel right you will be able to correctly shim the spur and sector. there should be a very minimal amount of play between the gear but still able to spin freely.

once this is all complete there should be no whining in in the motor or the gears and the whole box together should have a nice crisp sound. hope this help mate. if not then well... sue me. tahh

[North West Outpost]

Re: Motor alignment / battery strain question

when replacing the piston did you:

A: re shim the gears (correctly)
B: do nothing and just put it back together

To me it sounds as if the bevel gear is to high.

You mean too low?

You will pretty much deffinatly need more than one single thin shim under the bevel gear.

The quickest way for someone who doesn't regularly shim a gear box is to remove all unwanted parts from the gear box, then shim each gear on it's own. For now it doesn't matter how many shims you have underneath or on top so long as you have the right ammount. As said above minimul latteral movement but still able to spin freely.

So shim them one at a time then lay them out on your work surface making sure you know how many shims are on each gear. Then think about the bevel gear position in relation to the pinion. Followed by the other gears getting them at the right height.

[North West Outpost]

Re: Motor alignment / battery strain question

Ok well I'm pretty sure I shimmed the gears properly. I screwed the gearbox together with just the shimmed gears inside and turned them with my fingers. They felt loose and were able to spin freely. I only put one thin shim under the bevel gear because it looked too close to the surface of the gearbox without one... also the gears had little if any vertical play when pushing them up and down.

The motor and spring are stock and the rate of fire is better than before due to the new wiring, connectors and one less tooth on the piston (AOE correction) so I guess it's working fine. Surely the gearbox is supposed to whine a little bit, what with the motor and everything going on?

One less tooth from the back of the piston won't give any noticable increrase in rof. I would check that too as you usually need more than one tooth out of the way to correct aoe.

[Crude Skinny B]

Re: Motor alignment / battery strain question

oh yeah, thanks, I did mean too low

[Quibble]

Re: Motor alignment / battery strain question

Wow thanks for all the feedback I really appreciate it.

EBR-freak: Thanks a lot for the advice. I definitely need to rethink this.

Midas: The first tooth on the sector gear would have engaged with the second tooth from the back of the piston, making the AOE almost 1 o'clock. Now that piston tooth is removed it's almost dead on 12 o'clock so I'm happy with that. I tested it by hand before the final assembly. I'm confident that's no longer an issue. Thanks for the advice and confirming the rate of fire though, makes sense!

I think I'm going to have to buy another pack of shims and start again from scratch just to be sure. The battery and motor become lukewarm after prolonged fire, certainly not hot by any means. Since adjusting the motor plate and adjustment screw the whine has reduced somewhat and is now comparable to a lot of guns I have listened to on YouTube... still doesn't mean the shimming is perfect I know.

Many thanks again for the help I might try and re-shim before Sunday's game or just take her out and see what happens.

[North West Outpost]

Re: Motor alignment / battery strain question

Maybe we are saying the same thing, usually when I correct AOE I have to remove all the second tooth and some or all of the third.

Screething is usually just the tips of the pinion and bevel touching and missing, motor height too low. Whining can be motor height to high. But there will be a certain ammount of noise from both the motor and gear set.

[Quibble]

Re: Motor alignment / battery strain question

I think I have it running fine now. The shimming could probably be a bit better but after a few tweaks it is sounding much better. I have learnt a lot from this, thanks to everyone for your help.