new gears

[Ross]

I spent a long time shimming my new gears I purchased recently. The gun makes a somewhat higher pitched noise when I pull the trigger. Do new gears need to be worked in?

[THe_Silencer]

Make sure you put an adequate amount of good quality grease on the gears. Also, the amount of whine should be minimal or non-existent if shim perfectly.

[vondnik]

Whining is usualy the result of an overtight motor. Lithium grease on the gears pinion (if you are not using bearing bushins) and a small amount on the gears themself. Dropping lots of grease on the gears only leads to and extra dirty gearbox. Make sure that your shim job does not create any planetar friction betwine the gears. Never beleive that any gear is "selfshimming". A change in ratio or gear profile is going to alter the spound the box makes.

[ThunderCactus]

did you adjust the motor height?

[Stealth]

A new gearset is simply not drop-in. Manufacturing tolerances are different so you'll need to completely reshim the mechbox. This means checking tolerances between all gears as well as pinion to gear fitment.

[audi_bhoy]

Not to tell that some china made products can sometimes have quality control failures, happened to me that new gears would sound scratching and even after 3 complete shimming job it would result in the same horrible sound...

[Whiskey]

Either it's shimmed to tight, or the bevel gear is not shimmed correctly. I'm leaning towards the bevel gear ,as I have met very few people who can actually shim a bevel gear correctly.

[MaciekA]

Originally Posted by Ross

I spent a long time shimming my new gears I purchased recently. The gun makes a somewhat higher pitched noise when I pull the trigger. Do new gears need to be worked in?

All the other advice here is valid.

The other big thing in shimming and reducing whine is being able to execute a lot of iterations and shimming positions/permutations QUICKLY.

If you're putting your entire compression set and all your gears back in every time you test the sound of your gears, you are wasting a lot of time that could be better used.

Some people in here are telling you to focus on motor height and the bevel gear. In my experience, this is the single most important thing when swapping gears, a motor, or a pistol grip (all will affect shimming and pinion/bevel alignment). This is where you want to focus all of your energy until the bevel sounds perfect.

You want to narrow down the number of iterations in your search for the right mesh, especially if you are unable or unwilling to use a method where you can confirm the meshing visually.

Raise and lower your bevel gear until you see that the pinion is engaging it within spitting distance of what "looks good". Figure out a good motor height from there. I like to use the half-shell-with-pistol-grip-attached method and it's serving me VERY well. Some will disagree that this gives you an accurate picture of the mesh but even if you disagree with the method, it still gets you close enough to start somewhere and narrow down your search space.

Once you are close, test your sound by running the mechbox in the lower receiver, but with only the bevel gear installed (i.e. no spur, no sector, no ARL, no compression parts or spring). This will save you time. Once you have that bevel gear down the rest is pretty easy. Having a lot of 0.1mm shims (like the Modify Advanced shim set) is useful to get it super precise.

Once you have the bevel sounding awesome, put the other two gears in and leave the ARL out. Test, re-shim, etc, until perfect. Then put your ARL and compression set and do the final testing (including piston/sector engagement).

edit: I'll also add that isolating the parts so that you are only listening to the bevel and pinion making noise with nothing else running has proven to be a fantastic way to get an idea of what noise each individual part contributes without the distraction of the other parts.. This was the point of my reply. You can at least narrow down a sound issue to to (bevel + pinion) vs. (other gears) this way (unless you have some crazy stuff going on like the sector dragging against the cutoff lever, but it's easy to see that with the naked eye before making that mistake..

[Ross]

thanks everyone.

[wind_comm]

one of the things that happened to me whilst I was shimming my gearbox was very simple but hard as hell to google-fu an answer for.

I shimmed it multiple times and was very very sure I had it very very perfect, but it was still very very screechy. the culprit? pistol grip pinched the bevel gear axle on the high side, thereby forcing it down and screwing with the motor alignment and rubbing on the spur.

take the gearbox out screw on the pistol grip with only the bevel gear and see if it's rubbing or not. if it is, just file down the inside of your pistol grip to give it clearance.

[Ross]

this is very interesting. I adjusted the motor height and it didn't seem to effect the noise at all for some reason.

[voorhees -FWA-]

wind_comm is correct IMO, when you shim; start with the contact point of your pinion gear and your bevel gear and shim from there, not from the spur gear. If you are able to get your pinion and your bevel gears to mesh correctly and continue to shim the rest of the gears from there, your gears will last forever and your gearbox will run silent.

The best way to shim this way is to drop your bevel in with the lowest shim and then attach your motor and grip to see where it's engaging. You do not want the pinion gear in too far or not far enough, you want the bottom edge of the pinion gear to be flush with the outside of your bevel gear. You want to start shimming from there and there should be no movement up or down or wiggle from side to side from your bevel gear. Once you have this set, you can start to shim the rest of your gearbox and I bet your shimming will be flawless and quiet.

Here's a video tutorial on this process, he talks a lot and you do not have to drill the “peep” holes as you can see it through the cylinder and most will have a square hole on the top gearbox cover behind where the trigger goes.

Airsoft Minigun V2 V3 Gearbox Shimming Different Technique - YouTube

This is the method I use to shim all my AEGs and I have yet to have a failure...

[MaciekA]

Originally Posted by voorhees -FWA-

wind_comm is correct IMO, when you shim; start with the contact point of your pinion gear and your bevel gear and shim from there, not from the spur gear. If you are able to get your pinion and your bevel gears to mesh correctly and continue to shim the rest of the gears from there, your gears will last forever and your gearbox will run silent.

The best way to shim this way is to drop your bevel in with the lowest shim and then attach your motor and grip to see where it's engaging. You do not want the pinion gear in too far or not far enough, you want the bottom edge of the pinion gear to be flush with the outside of your bevel gear. You want to start shimming from there and there should be no movement up or down or wiggle from side to side from your bevel gear. Once you have this set, you can start to shim the rest of your gearbox and I bet your shimming will be flawless and quiet.

Here's a video tutorial on this process, he talks a lot and you do not have to drill the “peep” holes as you can see it through the cylinder and most will have a square hole on the top gearbox cover behind where the trigger goes.

Airsoft Minigun V2 V3 Gearbox Shimming Different Technique - YouTube

This is the method I use to shim all my AEGs and I have yet to have a failure...

+1 this is the way I do it now. You adjust the bevel on the "righthand" side of the shell, half exposed, with the pistol grip attached, by adding shims on the fat side of the bevel until it meshes with the motor properly.

While you're doing all this, you're unscrewing the motor grip's cap between each adjustment, putting it back in, and screwing the motor height adjustment in and out, watching the shaft of the bevel and seeing if the pinion "disturbs" the bevel as it comes in from the motor grip. Eventually, you get it to the point where it disturbs it a bit and then you back off by removing a shim or two until perfect.

Then you put the bevel gear in the other half of the gearbox and begin to add shims on the narrow side of the bevel (the side that engages the spur) until there is absolutely NO play but it still spins when you give it a whirl with your tool through the pinion hole.

Then you shim the other gears as low as possible but with the spur still high enough to engage the bevel and the sector high enough to clear the cut-off lever and engage your piston properly.

While you're doing the first "phase" with just the bevel, after you think you have the perfect spot for it, test the mechbox in the lower receiver, with pistol grip/motor, but without any other gears or compression parts and obsessively adjust from there until happy.

Use PTFE grease if you can get it. Buy 0.1mm shims. Use a powerful flashlight during phase 1 (the bevel-pinion phase) and look at it from as many angles as possible. Wiggle the bevel a bit so you can get a good idea of how much space there is between it and the pinion. Try moving it around at different angles so that you're not "fooled" by it settling at an odd angle.

[wind_comm]

credit where it's due, wasn't me that described bevel shimming. but yes, bevel shimming is the way to go.

I was describing how I solved my screechy gearbox/motor heating problem (even though I was/still am sure I shimmed it perfectly). my gearbox in particular is kind of a mixed blessing in that the tolerances are all over the place, as in each gear needs ~1.95mm of shims total. it lets me get the shimming freakin perfect (and I mean, SERIOUSLY perfect), but the gearbox being so wide causes fitment problems everywhere else.