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HomeAircraftHelicopterBeginners Corner › EXI 450 Motor won't stay put
08-06-2011 04:44 PM  6 years agoPost 1
Bladecpnitro

rrApprentice

Ga

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Am I the only Joker who's motor keeps sliding off the main gear causing emergency auto's? This keeps on occuring no matter how tight I get the bolts on my EXI 450 motor. Its been a problem ever since I got it. In fact it was my very first issue with this Heli during the 2nd or 3rd hover. When it happens its coming to the ground ready or not.

I've been lucky about 7 times so far and not tore my bird up doing this. Twice really lucky from 20 feet high it went down behind the cars on the other side of the driveway out of site and to my amazement it was sitting upright both times when I got to it, once was this morning.

I need a remedy for this. I've tried washers different bolts and they all last less time than the allen bolts that came with the kit. I tried 2 of these and it didn't make it through 1 battery.
http://www3.towerhobbies.com/cgi-bi...p?&I=LXRVA6&P=6

There has to be a remedy for this. I think maybe an abrasive washer with a button head cap screw might work. Or maybe I could get them tighter with a phillips or torx head bolt??

Any thoughts

If its fixed don't break it.

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08-06-2011 05:05 PM  6 years agoPost 2
Tag1260

rrApprentice

Ohio USA

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Loctite?

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08-06-2011 05:06 PM  6 years agoPost 3
salrica

rrApprentice

Raleigh,NC

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Nuts??!!
Nylon lock nuts???
With red loctite

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08-06-2011 05:11 PM  6 years agoPost 4
Heli 770

rrProfessor

USA.

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Blue Loctite should work, I always use it. You need to clean the threads and let it set at least 12 hrs.

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08-06-2011 08:26 PM  6 years agoPost 5
Bladecpnitro

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Ga

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12 hours Heli 770 I usually pop it in and go fly. Maybe thats why it keeps coming loose?? The Alpha 400 motor vibrates a lot with no load on it and I can easily see how it would vibrate the bolts loose.

I just put it back on with button head screws and flat washers. I ruffed up the down side of the flat washers with a file and I did use red loc-tite just for extra measure. I think when the motor gets hot the medium loc-tite loses its hold and the bolts vibrate loose. Either that or the bolt vibrates down into the aluminium block allowing it to get loose. There are notches there where those screws rest.

I'll stay close to the ground next few times I fly and keep an eye on it. I just have got it rebuilt after an inverted crash caused by the rear servo ball popping off the swash plate. The bolt was stripped back there and I was hoping loc tite would hold it in but it didn't. It came loose while attempting a rain bow and flipped upside down. It did almost no damage, bent the tail boom, feathering shaft, main shaft and broke a pitch link. The most aggrevating thing was the servos had to come out and be set back to 90 degrees. I had 2 stuck bolts one on the right front servo and one on the aluminum block. I had to saw a groove in the screw on the aluminuium block to get it out and once I had the block out, pliers got the one out of the servo.

I hate allen screws. I'd like to replace all mine with torx screws I think. I was almost ready to fly and realized my collar on the main shaft was to high allowing the gear to set low and drag the frame. No problem take the allen set screws out and adjust it. Wrong! They stripped. I got the soldering iron hot, applied heat to the set screws, found my best 1.5 allen wrench and finally did get those out and set back right.

For ever 20 minutes I fly this thing I must work on it 10 hours. I don't mean to be griping but this thing has agrevated me lately not to mention my piggy bank.

If its fixed don't break it.

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08-06-2011 08:49 PM  6 years agoPost 6
Heli 770

rrProfessor

USA.

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Loctite
It actually takes 24hrs. for full cure. Once cured it takes 482 degrees F. to break it down.

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08-06-2011 09:32 PM  6 years agoPost 7
MichiganFlyer

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Lansing,MI

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A little roughing up with sand paper to the mounting area also? maybe?

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08-06-2011 09:55 PM  6 years agoPost 8
Mputu

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Killeen, TX

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I had similar issue with my Trex 700N tail hub, which was coming loose no matter how tight it or what I used. I had to replace hub fix it once for all, even when I replaced the set screw. well sometime you might just get a defective piece, just a thought.

Fly hard, Land safe

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08-06-2011 10:00 PM  6 years agoPost 9
Mputu

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Killeen, TX

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still try all color of loctite and if they all failed replace something.

Fly hard, Land safe

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08-06-2011 10:32 PM  6 years agoPost 10
Bladecpnitro

rrApprentice

Ga

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I may need to get the bolts about 1/16 turn tighter than I can get them with my bent allen wrench too Michigan Flyer possibly. The last thing I want to do is strip the threads in the motor.

Someone else told me once I get the gear lash set to take the bolts out of the front of the motor mount, loosen the back ones and let it swing down where I can get strait on the bolts to tighten them good. That helps a lot but the problem continues. Sometimes it will gradually work loose over 6 or 7 flights.

I'll just let it set up 12 hours Heli770 and see if that will hold it, its raining here today anyway. If I don't have the bolts quite tight enough the motor can still slide away from the gear regardless. It might be good to have an extra bolt and nut in the slots in front of the motor bolts to keep it from sliding away from the motor.

If its fixed don't break it.

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08-06-2011 10:41 PM  6 years agoPost 11
MichiganFlyer

rrElite Veteran

Lansing,MI

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Yes, remove the battery tray to tighten the scews. I did. Your idea of adding some bolts behind the motor sounds like a good idea for your problem too.

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08-07-2011 02:00 PM  6 years agoPost 12
Bladecpnitro

rrApprentice

Ga

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Well I just flew 2 packs this morning and everything went great. The motor seems to be staying put for now. I even put red loc-tite under my washers so it will stick to the motor mount a litte.

I practiced auto's without killing the power. I fly up and come down just fast enough to make those blades flutter with a little forward, backwards or sideways movement and flare out at the end. I haven't got the nerve to hit throttle hold and try it. LOL!

If its fixed don't break it.

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08-07-2011 03:23 PM  6 years agoPost 13
Mputu

rrVeteran

Killeen, TX

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Good news I put hope it stay put for awhile, let us know how it turns out after more flights...

Fly hard, Land safe

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08-12-2011 11:25 AM  6 years agoPost 14
Bladecpnitro

rrApprentice

Ga

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Well the motor is finally staying put but I've landed my EXI twice now with 1 feathering shaft bolt almost backed all the way out. I said I'd never put max strength loc-tite on my Heli again but I cant take a chance on getting a blade slung at me. People that get hit with Heli's get stictches.

Im thinking about switching all the problem bolts on the Heli out for torx head bolts? Feathering shaft bolts, servo bolts, all allen set screws and motor bolts(hard to get tight enough) are problem bolts and hard to get out if they strip.

If its fixed don't break it.

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08-12-2011 12:08 PM  6 years agoPost 15
Heli 770

rrProfessor

USA.

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Torx heads won't help much, you can only torque a screw so much before you over stretch it and make it weaker. Good tools will keep screw heads from deforming. On the parts that are rotating use grade 12.9 screws(stronger than SAE grade 8). I never have a problem with Blue Loctite if the parts are clean and you let it Set.

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08-12-2011 08:06 PM  6 years agoPost 16
Melnic

rrElite Veteran

Columbia, MD,USA

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I use cap head screws and washer.
Blue loctite placed onto the threads at the motor end.
I don't think I've ever had a motor come loose.
Cap head screw should take a 2mm driver at least. Don't use a button head if it uses 1.5mm driver, that will just strip or you won't get tight.

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