The upper shaft 'T' head has a broken pin in it (the part that holds the blades. You can flip the heli upside down and slightly rotate the blade housing back and forth and IT SHOULDN'T do that. Another way to instantly identify it is dislocate the rotor head links and the upper blade housing should instantly separate) It's made of plastic.
Anyway, It's also called the "T.B.E." Toilet Bowl Effect. It's not 'really' what's taking place, it's move of a cyclic issue but the effect looks like it's swirling in a toilet bowl... You need to replace the inner shaft basically on the upper rotor. They cost anywhere from $4-7.00 bucks. It took me about 2 days of researching and purchasing another one to finally figure it out. There was another website that says the balance bar is it or the gyro has gone bad; this simply isn't true.
Cheers!
Thank you axnjxn1701 for the prompt and detailed response.
However, upon inspection of the upper shaft "T" head the pin you described was not broken. I disassembled the whole upper rotor assembly and nothing seemed broken, cracked or missing. I reassembled and torqued all of the screws nice and snug. After a subsequent test flight the TBE was still present.
The balance bar is in perfect shape and connected with the two buckle connects to the upper rotor assembly. There is no way for me to rule out the gyro (as far as I know).
I do remember when I first flew this helo its stability in a hover was rock solid. Now something is amiss and I am somewhat of a perfectionist so it bugs me. Let me also state that experiencing the engineering and quality of this helicopter as I troubleshoot is simply amazing. This is one heck of a chopper!
Any other ideas or suggestions?
Thanks again!!
Greetings again david13246. Unfortunately, I just spent @20-30 minutes taking some nice, hi-res close up shots, edited them and had them ready to re-post to this thread in the hopes to clarify exactly what I wanted to ensure you looked at in detail and we saw exactly eye to eye on for this specific point. Maybe it's me, but I can't find anyway to post these three pics to give you the specifics... Argh! Lol... Anyway, I'll just attempt to try language in the absence of photos... If after this breakdown doesn't seem to highlight the correction, I offer my apologies for this thread as it just might truly be a possible gyro issue your looking at. The only thing is, at first, ' I ' actually that that's what I was facing too. Like you, my Syma 107 was also rock SOLID in hover flight. After a week and a half of some OMG crashes, I abruptly noticed this swirling effect. So, onto the recap...(and BTW, this thread was exactly what I discovered/corrected to resolve this issue successfully on mine ~ hope it's good for someone else if this doesn't work for yours specifically... :)
If you are looking at the balance bar, right below it, you'll see the dual screws on the 'T' head. Just below that the actual blade housing has two screws holding (one each) blade. If you look at the center of this plastic piece/housing, there is actually a little plastic dowel rod (one on each side) that extends out from the 'T' head into this plastic blade housing. If you can manually hold the balance bar, then grab one of the blades and try to force move the blade housing head, this extended 'T' head pin is broken off from the main shaft. If you can't move it, then it's not. It wasn't until I disassembled the links and took it off did I then physically see this minute piece broken. This is truly the only section where I've found the deficit is at in the craftsmanship on this heli. Otherwise, I TOTALLY agree with you on the overall build quality. I'm quite surprised my blades haven't broken to pieces with all the 'test' flights the poor thing has been through. Low and behold however, I had found it was this extremely feeble area on the 'T' head.
If this isn't the case for you, I'm sorry it couldn't have helped. Like I said it took me quite a bit of searching to find out this was my particular issue. If you would by any chance like these more detailed shots highlighting this area in specifics, I'd be happy to send them to you with more details (or to anyone else that might need them.) After owning three of these all together with my daughters who are into these RC helis, these are truly well built helis.
Hope this helps,
Kind regards,
Rob J.
Email has been sent... Let me know if you don't receive them.
v/r
Rob J.
please help me!you seem to know what your talking about!
my s107 helicopter has been extremely problematic now its flying but then drops in the first 5 seconds I really need to know if this is broken or not soon (my return policy is running out) if you need more info please ask this is driving me crazy!!
thank you soo much!
Hello Kcaj608. The first thing I'd offer is to suggest you take a moment and check your surroundings for flight. One thing I was unaware of when I first started using 'IR' helis is that there are quite a few things around the house that can contribute to flight problems - and dropping like you stated. The first thing I'd offer is to ensure that you are directly (as best as possible) providing a clear line of sight from your transmitter (controller) to the helicopter. If accomplishing that, check around and see if you might have some really powerful living room lights (or possibly too MANY lights) around your flying area. I have a super bright desk lamp that when I was in a particular portion of my living room and pointed the heli towards this light, it would drop like a dead fly. For about three days I had no idea that something like that would 'actually' cause an interference; but it can... Researching other scenarios online, one post even mentioned they had to turn off their LCD T.V.! I thought, right... Well, another couple of days later, sure enough, every time I positioned the remote towards the heli with the T.V. on in the background, it seemed to produce the same effect and essentially cut the IR connection momentarily. I thought this was bizarre but remember, IR means a light source, not necessarily like the formula of a wireless 2.4g series where there is a different style of communication of the wavelength. So in essence, if you can look at your surroundings, and ensure other forms of electrical devices are minimalized in your flight area, you will most likely see this diminished all together. If in fact this does NOT stop the 'drop-dead' scenario and if it's always been like this, then I'd quickly suggest obtaining an RMA and return the RC asap! Last but not least, the charging of the battery being a Li-Po, requires a special set of directions. Ensure that once charged, you allow it a 5-10 min 'cool down' before use. Then likewise, after use, give it another 10-15 min. 'cool down' prior to charging it... Why, well, these particular batteries will provide a much longer life span if you follow these instructions. If you by some chance didn't quite follow this from the beginning, it is possible that the battery might be in a 'bad' state and unable to obtain a thorough and proper charge in the first place. Something to think about... I hope this was helpful. Fortunately these are normally very well, if not THE best built mini helis on the market. Not too much can go wrong with these initially. Again, if this has always been like this, you should probably return it. If it just started this, check your surroundings for interference. Best of luck! v/r Rob J.
axnjxn1701, I also have the same issue with my S-107 and in holding the blade housing, the balance bar moves slightly in the same plane as the blades. I suspect it is the problem you describe. I haven't searched for parts yet but will. Any clues?
Greetings PilotDen. I'm a little unclear about your specific explanation with the mentioning of, "the balance bar moves slightly in the same plane as the blades." Could you explain a bit more in depth please? You also mentioned that you have the same issue in holding the blade housing. Let me at least offer that if you have a broken T-Head where I described earlier, it simply won't stay stable airborne for more than about 2-3 seconds. Again, I'm a little unclear on the specifics your asking, but as a summary, mine was/would fly, but almost instantly start doing this weird toilet bowl 'swirling' effect. Under a deeper eye, and finding it really nowhere else (in my case) I decided to start taking the head apart and that's where I found that broken piece. I still have the pics I referred to with david13246's situation, if you would like, send me your email address and I'd be happy to forward these pics to you and see if they might help you in return. Again, IF your heli is doing what we previously discussed, this might be one of the answers for you. In the case of the great discussion with david13246's it didn't appear to be his resolve. Let me know and best of luck!
Go here - it solved my problem - the balance bar was not moving freely enough. I sanded the ends and it freely moved- problem solved!! http://www.rchelicopterfun.com/toilet-bo...
axnjxn1701, thank you for replying some time ago. Sorry I missed it. DHolsing pointed me towards a link and I will review it. Since I posted this, I've been educated on this problem and found the T-head broken. Hence, the "balance bar moving slightly in the same plane (rotation) of the rotors" due to the broken pin. I replaced it but the replacement part was not identical in that the bottom of the plastic head would not allow the shaft cover tube to slide up inside. So, i carefully drilled it out (#46 drill) and it fit. The balance bar fit snugly and may need to be loosened up per DHolsing. Anyway, the hover TBE is still there, but diminished. Still, it is not as good as new which was rock steady. So, I have more to do and learn on this one. I mentioned the less than exact part to the supplier and he sent me another T head and inner shaft PLUS the other shaft. Same thing, the T head is not the same hole size for the shaft cover tube to slip up inside. Makes me wonder if there has been a production change? Or, elimination or addition of that shaft tube. I certainly have more work to do on this but, hey, I'm a fixed wing guy and my C-182Q flies straight and level.... :>)
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Just a thought. Some of the Syma helis have 2 buckle connects and some have only 1. If your Syma s107 is flying spastically in circles and won't hover level and you have checked everything else try removing 1 of the buckles. YES they are that sensitive.
Fixed my Syma S107.
Thanks for posting this picture.
http://www.nacrc.com/images/heli/SYMA-S107-13.jpg
I noticed my lower plastic rods were snapped after viewing the picture. I figured if I reordered the part this would likely occur again. I drilled a hole through the center of the plastic shaft and cut two small metal pins for either side.
It would of been great if the center metal shaft could been secured below this point as I could have run the rod straight through. 
Here is a example of what I would have preferred to have.
If nothing is broke try lubricant. I had the t.b.e with nothing broke, and still after completely rebuilding with all new parts. lubricating the inner and outer drive shafts as well as the gears and pivot points was the fix.
My S107 would toiletbowl after moving forward. sometimes i could get it under control and it would hover for a while until moving forward again.
nothing was broken, and the balance bar was moving freely. the balance bar WAS bent a little bit. i replaced it, hoping it wasn't a bent inner shaft.
the difference is night and day, no phantom spiraling, stops when you want it and stays put.
sitting next to the new bar, you can see it doesn't take much or a difference.
I had the same problem. nothing broke but toilet bowled all the same. After rebuilding two times with all new parts. The fix for me turned out to be lube. lubricating the drive shafts inner and outer, plus all pivot points, and the gears. Good as new.
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I discovered that my s107G that was doing this didnt have a thing wrong with the copter. The problem was the CONTROLLER.I switched to using the iphone control app and the spinning stopped immediately! the problem was a faulty control stick.
I wonder if the pins are actually shear pins and serve to protect the gears when the blades directly hit something solid?
My balance bars were puched to far onto the stud, I popped them off and put them back on the ball of the stud and it flys perfect now.
Http://www.nacrc.com/images/heli/SYMA-S107-13.jpg
look at this picture it clearly shows the head. the two lower rods break.
its really hard to notice on the heli. to check for this problem the top blades should only move on once axis pivoting on these rods with the balance bar,
you dont need to replace the whole shaft only the plastic upper part
If nothing seems broken on th rotor shaft, try loosening the very top screw (on the balance bar).
This will allow the balance bar to move freely and prevent the "toilet bowl effect" TBE.
For one thing, there are only two channels. Although the transmitter shows a,b,c the switch has only two positions. The way to assign a channel to a heli is to turn it on and then simply operate the transmitter. The heli will lock itself onto the first frequency it receives, and start working. Before turning on the second heli, make the first transmitter is OFF, and set the second transmitter to the other channel. Turn on the second heli and simply operate the transmitter. The heli will lock itself onto the second transmitter's frequency, and start working. Then you can turn the first transmitter back on.
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Rob. Thanks again! While I "think" I know what your are describing if you could send me the pictures I would like to be absolutely sure. Please send them to me at david at itascapetproducts dot com. Thank you again!!
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