CYMA Orange Gearbox Issues

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This seems like a great one for our resident CYMA expert @RokSolid to answer… hopefully.

Twice I’ve put metal gears into the orange nylon CYMA gearboxes and both times it’s caused issues with the semi-auto function.

I’m not sure if it’s caused by a dodgy cast sector gear or what, but every time I put metal gears in I lose semi-auto. I’ve checked clearance to the cut-off lever and free movement and all good but still no joy… full auto only with metals in. Pop the nylons back in and everything works correctly again, so obviously it’s the different gears causing the issue. :man_shrugging:

I have a CYMA M4 CQB on the bench right now, metal gears were put in by someone else and I have the joyous task of making it right. Maybe a heavier cut-off lever spring?

Any suggestions and creative ideas are, as always, very much appreciated. :+1:

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Are you using the correct CYMA metal anti-return latch. They are longer than the one you get with metal gears

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Now that you mention this I had a similar issue with one of my CYMA M4s that I put metal gears in and Semi would semi-work ( sorry not sorry), it wasn’t really an issue as I built it as a kind of LMG so didn’t particularly need it.

Don’t see how the anti reverse latch would affect the fire control though.

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Ah, I didn’t know that but it explains a lot. I’d say the one in it isn’t correct… at times the AR latch sneaks past the ratchet on the bevel gear. But it seems to be doing ok on that score with a lighter piston spring in it… sort of.

It’s that situation where I’m working with someone else’s efforts, which is looking more and more like the cause of the problem.

I’m guessing the difference between the dedicated CYMA metal gears and these cast gears are what’s causing the problem with the cut-off lever and semi-auto functuon.

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Me neither - doesn’t make sense. But semi worked when I put the blue anti-reverse latch in with the metal gears. Local tech told me it was the problem. Nylon latch is still in there working fine. Could just be co-incidence

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Might be the next thing to try… if it sorts out fire select that should mean a CYMA metal AR latch would do likewise.

I agree though, hard to see how an AR latch can influence the cut-off lever function.

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Tried swapping out the short AR latch for the longer nylon original… definitely more positive but did nothing for the full-auto issue.

I’m guessing it’s the cheap-arse sector gear.

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Wonder if the standard latch being shorter let’s the gears reverse just enough the disconnector/ cut-off engage properly with the sector gear/trigger trolley :thinking:.

That’s the only logical reason I can think of ATM.

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Would a stronger spring on the cut-off lever make any difference?

I don’t get it, it’s free enough and seems to be doing all the right things… just not when it cycles. :man_shrugging:

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The nylon CYMA gears have quite a large disruptor cam on the sector gear.

Many metal gear sets that I came across, the Cam cast into them were nowhere near large enough to cycle the cut-off lever effectively or reliably.

This can be made worse with shimming, if the sector gear is moved away from the cut-off lever in the lower half of the gearbox.

Also check that it has plenty of free movement, as sometimes they are too tight where they mount or tighten up when they are screwed down.

You can actually use some Metal Mend or Epoxy to build up the cam profile on the gear set, or on the cut-off lever arm itself to get the required travel to operate correctly.

A good spring tension is required to keep the cut-off lever arm in contact with the cam on the sector gear, so either stretch the one you have, or see if you can find something a little bit stiffer to replace it with.

Good luck :four_leaf_clover::crossed_fingers::+1::grin:

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It’s been a hot minute since I’ve had a nylon CYMA getting metal gears. To make things worse I’ve never had one with semi auto issues. Though most of my builds got a480 motor and m100 springs because everyone wants the most out of them. Always had to sort stroke a tooth to safely release the pistons I put in.

I’d try using a stronger cut off lever spring, or a wells cut off lever (they were always plentiful at the shop due to broken metal boxes… And say what you like about wells but their selector plates and cut off levers are actual V2 spec).

Another trick I have done on some boxes was use a thin and wider cutoff lever spring together.
Thinner one inside the wider one.

As for the ar latch I used the cyma ar spring and SHS latch normally, I cant see how that would cause semi issue, but certainly had odder problems than that over the years!

Has the trigger been changed? If it has it might not be releasing the trigger trolley when knocked by the cut off lever.

I feel your pain, due to semi only fields I had to deal with many it won’t semi blasters… and it is often a painful process with many rounds trips opening the gearbox. It is best to only try one thing at a time though, as often you will chase your tail creating an issue when solving an issue that has similar symptoms!

Cast gears or SHS? What trigger? Stock trigger block? Spring, motor etc?

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Looks like everything’s stock, it’s just an orange CYMA with horrible cast gears thrown in it. Some shims which made it way too tight. They’re out now, minimal gear float and free spinning.

Sad thing is when I tested it in front of the owner the obvious problem was lack of AR… oh, and woefull FPS. Figured it just needed minor upgrades and a new AR spring, but it’s growing legs. The AR latch was definitely too short and slipping out, better with the nylon CYMA latch but not ideal. New o ring, full cylinder, M90 spring and it’s upped power but no semi. Worst part is, when I trigger pull on semi I usually release the trigger so it’s possible it had the fire select problem to start with due to an incompatible sector gear and I just didn’t notice.

Tomorrow I’ll check the trigger block for wear… I’ve got another one I can try. The cut-off lever looks okay so far, but the cam on the bottom of the sector gear may be too small to actuate the lever.

Easy way to find out is to put OEM nylon gears in it. If it works it’s down to shitty gearing. :man_shrugging:

What a pain in the arse. I hate working on boxes that have been hacked about.

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Nothing wrong with the factory nylon gears, unless looking to do stupid shit with large springs and spamming triggers!

Biggest FPS loss with the CYMA was the woeful piston and cylinder head seals, but also check the t-piece/nozzle sealing as usual, as had found some bad ones here and there.

Would rather have a Blaster that actually works reliabley with nylon gears than a Blaster with metal gears that doesn’t work at all!

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I agree 100%, Doc… but this one’s not mine. :rofl:

The low FPS was down to a shagged piston o ring and a cylinder head that had no o ring… just a few wraps of PTFE tape. :roll_eyes: Fixed all that up, good compression now.

Dunno who got into it before, but some weird shit evident. Something like a 60% ported cylinder, then an M120 spring to compensate, metal gears shimmed too tight, weak stock CYMA motor with metal pinion.

I’ll call the guy tomorrow… if it were me I’d put it back to nylon, M90 spring, decent cylinder head and nozzle… guaranteed 270-280FPS and reliable.

It’s weird working on other people’s gear… have to fight the urge to do what you’d do if it was yours. You know what they say… the customer’s always right… exceot when they’re not. :rofl:

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I tend to do better work on other peoples blasters, and leave some effort and concern out of mine because I can always fix it, and there is an experiment or unknown quantity/part of some sort in every blaster that is mine!

M120 spring is never going to end well in a nylon box! and 60% cylinder? why? Clearly this customer wasn’t “right”, and then it came to you? :rofl:

PTFE tape is a pet hate of mine… it isn’t for sealing, and in the rare scenario where it can help it is used wrong and in such vast quantities that it doesn’t work for long anyway! The CYMA 460 motor is not worth putting a metal pinion on. A wells or SLR motor is a big upgrade, and though not great motors, says alot about the cyma 460!

If it has had an m120 spring in it you may be dealing with a box that has been warped, which will have unknown reliability and may be the cause of strange semi issues, it would be hard to nail down the issue.
If you find yourself spending a lot of time trying to nail the issue, I would try to convince him to go back to nylon with good seals and mild spring. CYMAs nylon box in that for is usually pretty reliable and not bad performance.

Assemble the gearbox without the compression parts, put in the receiver and turn the gears manually while in semi with the trigger pulled, should give an idea if the semi auto mechanisms are working.

Semi auto issues can really do your head in. It is why I keep a couple of T238 Basics in stock at all times. Can get them for around $40, by them time you replace springs, trigger blocks, cutoff levers that might not be right for the gearbox, and different triggers… and spend time on multiple round trips in the gearbox… cost adds up quickly and may still not work!

If I can’t get it to semi after a few in and outs of the gearbox; I know it could take many more so it is cheaper for the customer to spend an hour of labour and a T238 Basic, and then they have reliable semi guaranteed.

As a side note, I can’t charge for work that doesn’t work out, I haven’t got it in me to do that!
For me to charge for the ETU and fitting, only works out $20 more expensive than had the semi worked from repairing the stock trigger setup. Most people are very happy for that, and that conversation itself usually results in them saying to not bother with the trigger block/semi issue and just go for the ETU, it is known results and removes a lot of variables.

Saves my time, using parts that may not work, and they get a blaster with a more sensitive trigger, auto prime, the option for binary, reliable semi and they can choose any trigger as the switch is very compatible with aftermarket triggers, where a stock trigger block is not.

Sad part is I quite like the feel of a good trigger block setup, the pull, click and reset etc feels really good when done well and working properly, and an ETU totally removes that. But most people like the shorter pull and sensitivity an ETU provides.

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Great info, @RokSolid . Very much appreciated :+1:and pretty much what I suspected.

I’m going to check on trigger block wear, maybe try a different sector sector gear, swap out the cut-off lever for another CYMA unit. But if that’s not fixing the problem it’s back to the owner.

The guy’s really got three options… revert to a stock nylon setup that just works, run the existing cast metal gears and sacrifice semi-auto, or run the metal gears with a T238 Basic and keep semi function. :man_shrugging:

It’s going to come down to how much he wants to spend. Shame Ausgel have sold out of $17 CYMA gearboxes, would have been a great option. :man_shrugging:

And I agree… I can’t in good conscience charge for work that’s unsuccessful either… doesn’t seem fair. Luckily I have zero overheads and I charge on a fixed quote basis (within reason, things change), not by the hour. :rofl:

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Yeah I wanted one of them, even went to look at grabbing a slightly more expensive gearbox and that sold out before I could pull the trigger on the purchase

Bugger

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At least I don’t get blamed for buying up all the spare parts and making them Out Of Stock for others anymore. :stuck_out_tongue_winking_eye:

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Just finished working on a full metal CYMA M4. Compared to the nylon ones, they’re such a joy to work with, those metal CYMA boxes. :+1:Not that the orange one’s are bad, just that the metal boxes are so well designed.

The orange terror’s in hiatus pending the owner’s choice of direction.

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Yes the metal cyma is a joy to work on. Made even more joyous just knowing you won’t break the gearbox shell, unless doing something stupid like DSG it!

Cyma nylon box is still one of the better nylon gearboxes though.