I am looking for help on my issue. I replaced the inner and outer shaft as well as the swashplate on my cx2 due to a little bit of vibration.
that was my first mistake , the vibration was really not that bad. Now , after putting it back together numerous times and everything visually looks ok when I try to lift off just about the time it gets light on the skids it develops a bad " wobble " i guess u call it. Its so bad that it will lay the heli over on its side. It reminds me of a spinning top as it almost stops spinning and it spins off axis badly. It was flying ok before I messed with it, just vibrating a bit. I have even replaced the new parts with my old parts and still have the same issue. I have not tried a new flybar yet which i just purchased. I even picked up some new blades as well. I am missing something 4 sure just can not put my finger on it. The blades seem to track ok , the swash looks level , my flybar is a little bent but I do not think its that bad. Has anyone "been there,done it" yet?

thanks in advance
mark

Check to make sure that the screws on the "inner shaft retaining collar" are lined up with the flats that are ground into the inner shaft. When lined up the screws will "lock" the inner shaft into place and prevent it from slipping in flight. Double check all the bearings to make sure they're seated properly, including the bearing at the top of the outer shaft just below the top rotor. On the flybar, grab both weights and pull them outward (away from the shaft) to make sure the weights are sitting at the ends of the metal flybar rod.

Are you 100% sure shafts your replaced are true? Spin the blades at a very low speed and watch the top of the shaft, make a note of where your throttle stick is when the wobble starts and post back here if nothing I suggested helps.

mpruett,
Some time back I put together a paper containing everything that I know about these helis. I'm no wizard, but there is a good bit of stuff in there. Sometimes reading someone else's methods will spark a thought and you'll find something that you missed. Anyhow, the silly thing became 10 pages long and with a couple of photos in it it's a pretty large file. If your email will handle 20 megs I'll email it to you if you like. Or I can skip the photos and it's just a word document. Of course there's no cost, it's just something I put together for newbies - and I still use it when I get too frustrated to think straight!
Let me know. PM me with your email address if you are interested. IF not, Best of luck - and we all want to know what you find when you find it. It's part of the learning process.
Have a good weekend.
Soloboss

I have found a very slight wooble on the top bearing when turning shaft at slow rpm. Both the new and the old shaft seem to do it. I guess a very slight wobble turns into a big wobble at top end with rotors. I will keep looking as well.

thanks

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thanks !!!!!!

I have gotten most of wobble removed now. I had to tap the top bearing cap on snugly to remove most of its wobble and installed new flybar. There is very little vibration now and both sets of blades track well under load. I still can not lift off tho. just as soon as it gets light on the skids it is wanting to wobble all over and will go down on its side. I tried to eliminate motor mixing as best as i could beu could not. Could this be a proportional mix issue of some kind ?? The tail is not wanting to spin around , it looks like a spinning top as it about to stop.

thanks

What you call a slight wobble at the top shaft is the reason that I went to the CNC bearing cups. I couldn't get the plasitc bearing cups to seat squarely. If you have wobble at the top, that wobble messes up the fly bar as it spins. The flybar may look fine at rest, but at speed you aren't spinning it centered on the shaft. You are spinning it in a wobbling circle and that will bend the flybar at speed.
If you have a digital camera, spin up just the upper rotor in a dark room and take a photo of it from straight above using the flash. The flash should freeze the image with a little blur showing the actual track of the upper hub. Or don't bother and just take my word for it. At any rate, the wobble is very likely bending your flybar at higher RPM. Is that the entire cause of your problem? I don't know. But I do know that a flybar that's not running true FOR ANY REASON is an issue - and it's not making your life any better at all.

ok. I have balanced blades , removed most of wobble from shaft. When I spin it up now there is very little if any wobble or vibration on main shaft. Installed new flybar. Checked balance of machine via the holding on to flybar when its 90 degrees to flybar. Still when I spin up and get light on skids its all over the place and will quickly go to its side before lift off. Blades track well as well. Its almost like the swash is way off allowing it to turn over before it lifts off. I know its something I have doen because it was ok before I started fixing something that was not really bad in the first place. I am the type tho if it has a little wobble or vibration then I want it gone. haha Maybe in the future I will not be so picky. Anyway , I think my next step is to check swash again. I have adjusted a bit on gain and propo thinking that might be it but I do not think so. I will have to readjust that when I get her airborne again. There is not that much that be causing this so I would not think its this hard to troubleshoot. I appreciate everyones help and ideas.

Mpruett,
does it always tip over the same direction? From your description it sounds like the problem is so repeatable that you can predict what's going to happen next as it lifts. So, as it just starts to lift, can you control the tip-over by counteracting with the control stick (wants to tip left - add enough right stick to prevent tip-over).

I have been in your situation exactly. The heli wouldn't lift, but it would just tip over. It always flopped over to the right. BUT, if I gave it full left stick it would just barely tip over so I knew that it was way out of adjustment. I don't recall how I got into that mess, but it was either a crash or I fixed it 'till it didn't work any more. I'm known to do that.
So - To tune my swash plate, I used a really slick table top and set the heli on that table. My nephew has a play table here and it has low sides so the heli doesn't get away from me. Anyhow, before the heli gains enough thrust to lift, it will slide sideways in the direction that it will tip over as it gains lift. With the body removed I can adjust the linkages so it doesn't try to go anywhere as the power comes up. I did learn that the heli cannot be trimmed to sit perfectly still because it's sitting in it's own ground wash. But still, the heli had a strong will to leave sideways and I was able to tune it using the slick table-top. I adjusted the length of the servo control arm links over and over until, as the heli started to get light on the skids, I was able to 'drive' it around using the sticks. When I could control it on the table top, I could fly it again.

That's how I did it. Maybe it's worth a try for you.

OK yeah, and to adjust the proportional axis, I taped the heli to a lazy suzan that sits on the dining room table. That worked pretty slick.

thats my problem to the T. It always seems to want to try and move right and forward.... I have sort of tried what u r saying but I think I need to spend more time as u suggest. As u , I am not exactly sure how i got here but I am here and need to get it resolved. Even tho I am a beginner i am mechanically inclined so this just drives me nuts !! lol Hey , thanks again and i will be trying what u suggest.

mark

excellent idea !!! I have a trex and I trying to build so i will be using that one again..

thanks