My CX2 started making some clicking noises and soon after the upper rotor stopped turning. I took it apart a little and noted that the main gears were a bit stripped. The odd thing I saw, though was that the stripping was only partially across each tooth. The pinions are not engaging the main gears properly, so a lot of partial tooth stripping is occurring. I bought some replacement main gears and took everything apart (Jeez! Those little screws were frustrating to loosen up).

Unfortunately, the new gears don't look like they're lining up with the pinions any better than the old ones. It *looks* like I need some extra spacing to put a little more distance between the gears and the fuselage. As it is, the outer shaft gear isn't even half covered by the pinion gear. Then the inner shaft gear is halfway on the outer shaft's pinion gear and halfway on the inner shaft's pinion gear. It's not going anywhere unless part of it starts stripping.

I don't think I've knocked the motors out of alignment or damaged the frame in a way that would explain this problem.

Looking at the schematic, it doesn't seem that I'm missing any parts - and having seen the old gears, it looks like this problem was somewhat "congenital".

Any ideas?

Hmmm. Sounds like something is upside-down. Let me think about this and get back to you.
Are both gears too high or too low?
I must ponder.

Well, with the heli in the upright position, they're too high. They're too close to the fuselage.

I thought about upside down parts, but they're exactly like they were from the factory. They're just like they seem they should be from the schematic.

It seems that either the tolerance of the frame weren't quite right or I need some kind of extra spacer(s) in there.

Chris


I have some extra CX2 parts so I made a mock up for you of what the gears should like and what parets go where, to the eye. The only thing missing is the last piece which is the collar at the bottom. However in my flying CX2 you will see the collar and the mesh alignment of the gears. You may have forgotton or lost the bearing that goes up in the bottom of the chassis, that and the thrust washer in my picture make that spacing from the gears to the chassis. Hope this helps!

JPee

Great pictures, thanks for putting them up!

Your pinions line up with the gears MUCH better than mine do. Just from the pictures, I'd have to say that the main motor shafts on my cx2 are too long. I have no idea why that would be the case. It came from the store this way.

So where the pinion you have that turns the outer shaft's gear is right up against the fuselage/frame, mine is a good pinion height further away.

This is really disturbing since I don't see an easy adjustment for this problem short of trying to put some kind of shim under the motors.

Chris,


Most Hobby Shops will let you bring it in, review and sell you parts. I would find it very difficult to believe the shafts are you long. But clearly something has gotton out of wack! If you can't take it back to where to got it then go to your local hobby shop and let them lay an eyeball on it, the fix maybe simple. Also Horizon Hobby the maker of the heli holds a 12 mo warranty and longer in many cases.

Good luck JPEE

Okay, so what had happened was that the outer shaft motor's pinion had slid up, which caused all the grinding and gear destruction.

The hobby shop (Hobby Town in Cumming, GA) that sold me the helicopter a couple of months ago said, "tough luck, buy a new motor for $10". A little frustrating that the thing was obviously defective and they wouldn't stand behind it - but at least I got it working again for the price of the motor and new gears.

Although now I have a new problem in that the outer shaft doesn't turn as freely as the inner one. I definitely notice that the lower rotor doesn't spin as much after I power down. My guess is that in the extraordinary struggles I had in getting the little screws out the first time, I may have negatively impacted a bearing or something. It flies reasonably okay - although I have to now trim the rudder control all the way to the left and it still turns a bit on me.

Thanks for all the help, though! This forum was a huge assistance.

Probably the main shaft is bent. That happens all the time with CX2's.

Hello Chris,

JPee again.

I just bench tested my CX2 and the top blade always spins more freely and once landed it is the last to stop spinning. So your OK on that. It would nearly impossible for you to damage a bearing, however as Bry said you may have a bent or binding outer shaft. Take your finger and stick down over the top blade and spin it slowly and feel the resistance you get. Then stick you finger in the best way you can and do the same for the lower blade. On mine there is just barely a little more resistance on the lower blade. You can also without the body on look under and check the gears mesh and see if in fact there apears to be more slop in one gear over the other. When you had the shafts out did you MAKE SURE you put back in the thrust washer between the main shaft gear the the bearing in the frame?? Look at your manual. I think it is part 044. Next, also check part 020 that is your main shaft retaining collar and you may have pushed it down and tightened it to much and that is binding the bottom of the main shaft gear and the top collar which again with the bind slow down that blade and make the heli need the radical trim adjustment on the rudder. Do you have a blue heat sink on the motors. It is a small blue finned piece of aluminum to help the cool the motors. They have bene know to tweak the motors in such a way that the motor is driven into the shafts gears and bind too.

Let us know how you make out................JPEE

The top blade will always spin longer because it has more momentum because of the flybar weights oh and to fix the spinning to the left prob just adjust the proportional trim pot on the 3-1 or in my case the 4-1. Good luck tell us how this helps