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Tearing my AEG to bits... What do I need? Is this normal? etc....


Arwen
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So, after not hearing back from a tech I asked to have a look at one of my AEG's (Falkor Defence Recce) . I decided I'd try doing the work myself, and started last night by removing the gear box from the receiver (harder that I thought due to the over engineered ambidextrous bolt catch thing!).

First off, I'm taking it to bits partly for my own amusement, and partly due to the fact it probably could do with a service as it is noisy, and sometimes misfeeds.  
I also will be changing the barrel and hop unit, so figured I may as well order any gear box bits I need at the same time. 

 

As expected I found masses of grease everywhere... It is truly horribly how thick the coating of grease is on everything... look at that massive blob! 

image.png.5d6a373acdf3bf02f9b915c74a7bdeda.png

 

Once I finally managed to remove the gear box, I found even more grease, and the bearings seem to be weeping a dark coloured oil... Is this normal? 
the bottom bearing in this picture also feels... odd. I can press the centre of it and it pops out further on the other side. The rest of the bearings do not do this. I assume this means it is not shimmed correctly? 

image.png.dec82d3158141b5100e1b50f496ce7e6.png 

 

And lastly for now... My tappet plate seems rather chewed up and bows out slightly... So I'm thinking of getting a new one. However it looks like no other m4 tappet plate I have seen online. Can anyone tell me what version this is?

 

image.png.12113313f8c650032ec10922af21e233.png

Rear:

image.png.4a58492555fecd64dcda38eb5aebed66.png

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I think @Iceni is probably well versed and better at wording this than I am. If he hasn’t responded by the time I get back from work I’ll attempt to help you.

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After more googling I now realise that black plastic bit is the selector plate, not the tappet plate :lol: I'm opening the rest of it up this evening.... 

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Bearings are lubricated with a specialist grease, so being a different colour is normal, it leaking out is normal.

 

The bearing popping is normal, one of the reasons people replace them with bushings. Or you can glue the bearing outercase to the gearbox so they can’t pop.

 

Shimming is purely for the individual gears. Nothing with the bearings, changing bearings/bushings can change the amount of shimming required.

 

The selector plate looks standard and I would probably replace it. If your in the gearbox giving it a service, check all the o rings and your air seal, especially on the Nozzle, also check for wear on the nozzle as this could indicate your feeding issue.

 

Make sure you watch a disassembly guide for the V2 box first, just so you know exactly what to do so you don’t have to play hide and seek for parts!

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12 hours ago, Arwen said:

it probably could do with a service as it is noisy, and sometimes misfeeds. 


It looks like a well used gun so a service is probably a good thing.

Noise tells you a lot about what's happening inside a gun. Crunching/popping is generally bad but gear noise isn't so much a problem at 350fps.

The selector plate looks like it's a little worn, but functional. If it works leave it alone is the general rule of thumb. So I wouldn't replace that part. Just keep the biro spring nice and safe as it's a vital part.


Misfeeds are generally caused by a worn tappet plate. The tappet plate is an odd long bit of plastic that sits under the cylinder and holds the air nozzle in place. The place where they wear is at the lug where they get pulled back by the sector gear. Once they start to wear the air nozzle stops retracting fully. This stops the BB's getting up into the hop unit. A new tappet plate isn't expensive, but it must be matched to the gearbox type. In your case it's going to be a standard version 2.

https://www.ak2m4.co.uk/internal-parts/tappet-plates/zci-tappet-plate-v2


Grease is good. Just because it's thick and sticky doesn't mean it's not doing its job. The grease in the pistol grip looks to be silicone grease. It's a cheap grease that is suited to plastics, and metal on plastic applications.

Gear grease (metal on metal) comes in more variants than plastic greases. You want something that has the potential to lubricate, absorb sound, and stay moist. I use a soft moly grease. But there are loads of greases that will work.



-------------


For rebuilding and servicing:

You need,
Grease, Shims, O-rings, As well as any replacement parts for the gearbox.


For the hop it is advisable to have a new bucking if you are servicing the gearbox since you have everything out already.


Shims are cheap enough. £3 a set. Get 2 sets so you have loads of extras.
https://www.ak2m4.co.uk/internal-parts/bushings-shims/shs-ra-shim-set

 

O-rings I buy in bulk. Do not get them from an airsoft shop. Get them from a bearing supplier. Expect to pay pennies for a single o-ring but also expect to have to buy more than 1.

There are loads of materials and hardnesses for rings. But for a standard AEG you want nitrile (NBR Or Buna-N are also terms for this material) and 70 deg hardness. In o-ring terms this is bog standard.

You have 2 options for the piston o-ring 19x2.5 or 20x2.5. 19mm is standard and fits like normal. 20mm is slightly oversized is harder to get in and wears faster, but gives a much better seal especially with problems piston/cylinder combinations, but the larger rings need a better grease as well. The added friction for the larger rings is mostly mute due to the way the ring expands and puts force on the cylinder walls, I have not seen a gearbox slow down for having an oversized ring in it. Do not use oversized rings in ported cylinders.

Rings are measured as the thickness of the band (2.5mm) and the inside diameter (ID).  Be careful on the order page as inside and outside dimensions can be selected in the menu options.

Typically it costs almost the same to have 2, 5, 10 and 50 rings. So it is universally better to buy 50 and have loads of spares that you can give away or store.

It might cost £3.40 for 2, £4 for 5, £4.50 for 10, And £5 for 50.

These guys do free postage on all orders. And will be able to supply cheap o-rings if you go for the 50 pack option.

https://simplybearings.co.uk/shop/Seals-O-Ring-Seals-NITRILE-O-Rings/c19_4501_4705/index.html


 

Grease is a crapshoot at best. Some on here will rave about some miracle grease that does all sorts of magical things. I'm not one of those people. For me there are 2 decent greases for an AEG. Soft Moly and Silicone with PTFE. These are the exact greases I use £6.50 for both. And they will last a lifetime.

Silicone with PTFE. For metal on plastic, and plastic on plastic.
https://www.ebay.co.uk/itm/SYNTHETIC-SILICONE-GREASE-WITH-TEFLON-50g-TIN-2HT-PLASTIC-SAFE-LOW-FRICTION/391399159157?hash=item5b21353575:g:4sYAAOxyuCJRbx-p

MOS1 Moly grease. For metal on metal.
https://www.ebay.co.uk/itm/Molly-MOS1-Grease-for-Airgun-Servicing-50-GRAM-TIN/173589020123?epid=650435926&hash=item286ab63ddb:g:tisAAMXQHU1RrnWG


 

Once you get the box open and post some pictures we will know more about what you need internally.


The bottom bearing/bevel gear popping is pretty common. They tend to get shimmed up to the pinion of the motor, but the other side doesn't matter so much since the motor is going to hold it. So without the motor it's pretty common to see movement on them.

The grease on the bearings is perfectly normal. Expect there to be black areas, Where metal rubs on metal even with a grease you get surface wear, and this colours the grease black.



For the upgraded barrel and hop unit: AK2M4 has you covered.

I'm a big fan of the ZCI plastic rotary hop unit for M4 platforms. You may have to file the ring a touch if it's catching on the front of the gearbox. A 45degree chamfer done with a file about 3mm in from the rear edge of the ring is more than enough and doesn't hurt the units function.

Again ZCI for inner barrel. There are loads you could pick on the market, but the ZCI is hands down the best value. And I don't think I've ever had a bad one. Avoid barrels with a coating, or alumimium barrels. Brass or steel only.

Hop rubber is sort of a personal thing. I love the prommy purples with those rotary units. Dropped straight in, no flat hop just standard on the mound with the stock nub. It's the perfect cold weather bucking alongside the G&G green.

The 50deg clear guarder are also o.k. If you want to spend more in the hopes of better accuracy go the maple leaf 50deg route. Keeping it soft will give you better winter performance at the cost of a little durability, but that isn't going to be an issue because you will know how to change it when it wears out!

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Thanks for all the info and tips guys, much appreciated!

The noise from it sounds like grinding/crunching, so I was expecting to find some worn teeth or metal bits. however... it all looks pretty straight and damage free to me. Within the tons of grease I can see what appears to be metal shavings (like you find in a first oil change with a motorcycle...) however I cannot see anywhere that has been scuffed. 😕 

Some pictures...

image.thumb.png.6498548ee99eba0a28558707eb1f5db9.png

nfTaRKB0rpAKrEP8CYFphq73KOF9gBtvIia-8B2oXPG_J0UttRo6sjpptDdsTj0Ko4opVaaotuwChC9wEgMWGN5JTNrlBATfkeUnQeTbhabim9SvePEnlsS6mXogF4kYsEAhyGyIaorfrUCL0f7pnSsGtB0ZPVapuc5kMulCDgKUnyyxokccSY50e0n9gvYHnB_Ekw5Ri5DuwGHyNEUcPXpeohuY98RGs-zyWBXeRsWBMp_SRwoSiletZ4_kJ-SsqtwU7pvmyAcJSc6OMPpzxQ9FOWgrZJarT6aDdN7K75VnSUPkd2_gI5rgW9obkNPKnsHfm3Bel6UIrLoji3HRfSd0e6gCxLBT4Jo0i9JWuAJm9sU5b2C4kB7nq2RuJAQ1rPiWmS-yPYnWpnEM0lBozSfU6aB87bcziMcuyCrKyqkIKog4OuvwiKWLBvpZ0-4bJbV1Zruy8cztAjCjO_zHL8VR5sTdDYD2NzsVFnWHH-xtPG8DUdOVbSw5o7NWR2T5oDRklmL0olRo2J1re1Wq-Ld9j4r3o7CbvU6R3E9kn8QrWqpxx0mzvb8Ck1WRMjkqHzSrN_YaZ_NaCcqs2LFPiUfQ2h40uN5TJk7je-Z5ScWuoAvH0-9mIl_U0KFU2YgS=w1411-h1058-no

 

wIXtP3ZGXA2bIH8PYEScxKzbLjsW3Qdce5c-osedSPiOlMO7o77kM054Wuuf2bExnUQ0ZeH3NgGMVL2RPTnnqiVmctQzI0U6Ixistpj6tKe3bWJg_n_1WE9_TN2CqDua29bbf1ZzczMPz24E9DNVLGnaWXuFeI1uYAeryT_Irvep5JDjrmLboYaQExI-SXTymd-pulnqFLKgEYe7oaDzOgUntuefJ2B2L3qGcMqx25trmBzxz5YSp8RXkT3V0UEtV3fK4XiH6-otP3gxvEnrRTt1HPDeIiyIiBFmV6TWLwN9FrfSLRTiepBZhCcFKLp6mAU8oSP4hsuV21cv6CBFQ5WWQrCNn-j3YnGsjb10oVX9y3dErkZjbM9wY6Sw1hgHU1ziyj7pdu5HagR-RWDZJSGJPyxY4C7nrQ66C0VQv-48xh4WBvm5a6H-Vv7-o4wwdKB9mKh1bqqdstCfkrg6CDA_2AlgxAhzMSadzUNe78VsALrwmQSrgYMvHDYLOjBaCkh9jOnj0aO_DMYKEs7oGYJOKno8YwPDBMOhOVGhUfuGvp-379UvW5VRVQkWnjNgDTMajs__UPLQMrOq8X63P3vEetAnAmrvjPqajmsfr5ANMuMC1ve5STg1cxJRv836=w1411-h1058-no

 

The tappet plate doesn't look damaged to me (I've forgotten to take a picture of it...), certainly not as scuffed up as the selector plate. However it does feel very pliable. I thought they were meant to be stiff?

 

As for barrels and stuff, I would get the ZCi, however it never seems to be in stock in the length I need - 430mm-ish. I'll probably end up going for a laylex Prometheus one.  I've got a selection of hop rubbers so I'll play around with what ones works best with the hop unit and flat nub I have. 

 

Thanks for the links @Iceni those prices are more my style! :) 

 

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Grinding noise looks to be from the sector gear.

There is a nub on the lower face that is catching the cut off lever. It's wearing the face of the cut off lever and catching it. You can probably file the face smooth with a nail file.

44488225315_8b32772f50_o.jpg

43585912500_9d8ec781fe_o.jpg


The tappet plate looks like a cheap one I would replace it. It might be riding up because it's so soft and catching the gears a touch. The ZCI one I listed should be much stiffer. There is a good chance this is your misfeed issue.

It might be worth doing the air nozzle as well. Measure it and make sure it is the correct length. Often cheap ones are slightly shorter. It wants to be 21.4mm. If it's shorter than that replace it.

You need to check each bearing. Grab it thumb on finger, and make sure they run free and smooth when you put pressure on them sideways on. Any grinding feeling you need new bearings.

The engagement on the pinion looks very shallow. That should be corrected. It looks shallow because of the grease dispersion. It might not be. You need to do a motor height to bevel gear reset. There are loads of threads on how to do that. It might be good I'm only going off the grease and face wear on the teeth.

Bad pinion engagement can produce a lot of noise. Gear chatter and grinding.

45402507031_05cf051192_o.jpg




Give it a good clean, replace the parts, relube and rebuild.

The only other picture we need is the teeth on the piston.

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Thank you very much! That's exactly what I was needing. 

I checked the bearings last night, they seemed to run smooth, with no notchyness. I'll get reading up on fixing the motor height, think you've found the reason for the noise for me :D

 

The piston teeth are all plastic, and look unchewed (only pic I have of it jsut now, can take another one later though )

image.png.9b015a07fed299337a7cdb66a3f391a2.png

 

I was thinking of replacing it with metal teeth... but then got thinking should I stick with plastic as pistons are cheaper to replace when worn than gears? (I was thinking this one maybe? 

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I wouldn't bother replacing it. There is no point in spending money if you don't have to. A full metal rack is useful if you are running a hight stress build, but for a 350fps 20rps build a polymer with 1 metal tooth is not a problem.

If you wanted to add a basic mosfet now would be the time to do that.

As for the barrel length you have a 3/4 ported cylinder. So 430mm even tho it is stock is a touch too long IMO. It might be worth sourcing a non ported cylinder, and running a 363mm to get the consistency up a little.

He should also have his ZCI order in on the 22nd of Oct. So that generally means the barrels will be back in stock @ak2m4

 

The Prommy purple buckings I have no idea about. He hasn't listed a due date for those and it would be my pick for a winter bucking.

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Just a little update -

All the bits arrived, I decided to stick with the plastic piston, however did order a new head. This has solved the very poor seal I had (And didn't even know about until I tested it)

 

So I removed everything, cleaned, replaced the piston head, tappet plate and selector plate. Adjusted the motor height, checked AoE and shimmed the gears where needed. I must say, the most difficult part was the requirement for at least four hands to hold everything in place to get the two halves of the box back together!   Popped the spring back in and connected up a battery. Was very pleased that it worked first time and didn't sound awful! :D

 

DxMKitesL60KZ2IeoT4yW4D7f9xh30CjExdOBozpav4NVSkGcpP1AiIhmjijzDJ4zHE26mngkJK1JtsOd2x4t8XkWm_5nxr-G4B9WLw2lHD5UYEkkv_DBqhLip8OTmTdtNqdFvUW3gjMnkIPVI7qEGBxR_KEvGro42XFMM9M7syWsoTEScXyrju-qYLHsYkd-E774hdlwRGxupYkR3DUHzRcWUdKgzb7ur-wpBE1bDzEtxoZo6I0uJ6HR7BPJmzN2g-o4oBstHdyBMrTzcyDB2Swxz9IcDp0A7Vhbs98r8wtHinLx_7Xml-phEjSUKPbjez9za5cskf2i8pSyZZayTTYXNRslrLQHH48ZuZOnd_yoe5eeVav8AaupxyXjfqSvg3XdPHXgzCEmaU4jAk4sg3SwHlm7hqe7PkoG5msB4hH70oUdjTInEQLCnAHQzFtlZVr_OmuwC7004L12XTiIVAjvfD-5xAtQmR6zd6cRqh2LT4eCWRW5OF1GCXauDqdKwR2ZQmkooAdTJWxyyHNInA-mjC9Dbum0Wzi5pTb42KEBoruKjaBvGbO4qoHkookXrCTW-Q8uYnULSq--j9utk6ZPqXdZtyeuU0vjlCmejEiiLO9ox0I-I7FHd44oRGn=w1264-h948-no

 

Tonight it is the time for hop and barrel mods, then chrono it and see if I need a downgraded spring due to the very poor seal I had between the piston and cylinder, probably from the day it arrived.

 

Thanks very much for the help and advice @Iceni, I feel like I've learned a whole lot more about my AEG's now !

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17 hours ago, Arwen said:

I must say, the most difficult part was the requirement for at least four hands to hold everything in place to get the two halves of the box back together!

 

Preach it.  I bought some flat neodymium magnets to stick on the shell under each gear and particularly the anti reversal latch.  They do seem to help to hold everything in place while you get the shell together, and prevent the whole thing going Buckaroo.

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3 hours ago, lukeB said:

I've been trying to find someone that has the anti reversal latch clips in stock, but at over £10 with delivery I think some magnets might be better.

 

Only place I've found them so far

https://airlab.parts/products/hsa-anti-reversal-latch-clip?variant=1095938023

 

 

 

 

 

 

 

Not many places sell those, I have one and it IS great. You can get it direct from HSA on SHapeways https://www.shapeways.com/product/FRR9AKKGR/arl-clip?optionId=17951847

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Ordered 3.

 

Then watched a tear down vid of a Krytac this morning and realised they have a post in the gearbox shell for the latch, so I don't need one 🤦‍♂️

 

 

 

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