LMH Helicopter Discussion of all LMH helicopters both electric and glow.

Lite machines TR gearbox defect

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Old 06-23-2007, 02:42 PM
  #1
FlyingFish
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Default Lite machines TR gearbox defect

Need your opinion and experience!
I’ve been flying corona 120’s for about 3 years now and have noticed
That the tailrotor gear boxes are very fragile, even if you don’t have a
Crash, the gear boxes would sometimes fracture during normal flight.
When I ordered a few new gear boxes sometime ago from heli hobby,
I noticed that the gear boxes they sent were improved and made stronger.
I was delighted to see this, however I’ve also noticed that these new
and improved gearboxes are very, very hard to assemble onto the
tail booms, the fit is just to tight and when placing the gears inside these
boxes they don’t mesh properly and they click and jam up. I’ve tried several
new gear boxes with different tail booms, some fit better than others, but
in the long run all the gears never really work right nor do they run smoothly.
After searching through my spare parts bin I found an old style gear box
and installed it in 3 minutes with no dificulty at all and the heli’s tail rotor
now runs as smooth as silk with the old style gear box.
What is up with these new tailrotor gearboxes, they really aren’t any good. [:'(]
Have any of you guys run across this problem too ????
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Old 06-24-2007, 07:58 AM
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Default RE: Lite machines TR gearbox defect

I never used the stock box (older or newer type). For my 120's, I use chopper-1's that will work with stock wire drive and belt drive and totally indestructable, or a BT crazy case which only works with the belt drive. Chopper-1 no longer makes his. Maybe you can post in the FS/Wanted forum. If you want to convert to belt, BT's is also tough to break and he still sells his.
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Old 06-24-2007, 02:15 PM
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Default RE: Lite machines TR gearbox defect

does anybody have any other links to guys whom still sell carona upgrades?????

I went on BT's website and all his prices are listed as $0.00 is he still selling his products ?
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Old 06-24-2007, 10:34 PM
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Default RE: Lite machines TR gearbox defect

You have to order them from helihobby
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Old 06-25-2007, 11:46 AM
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Default RE: Lite machines TR gearbox defect

yea I saw that Helihobby has them, are all of BT's aluminum tailrotor gear boxes only designed to be used with belt drive conversion, or does BT make stock style gear boxes made of aluminum for stock wire drive.
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Old 06-26-2007, 07:55 AM
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Default RE: Lite machines TR gearbox defect

FlyingFish,

I do not have the answer to your question, but I do have a suggestion for making the gearbox you have stronger.

Get some 2oz fiberglass cloth (available from your LHS), and some plastic zap (CA for plastic).

Cover the outside of the gear box with CA and then wrap with the fiberglass cloth. It helps if you kept the CA in the freezer, this will slow curing time.
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Old 06-26-2007, 10:52 AM
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Default RE: Lite machines TR gearbox defect

In the past I have coated the gear boxes with epoxy as well, this helps for a while, but I found in most cases that the plastic the gear box is constructed from is made from a kind of a non-stick plastic, and found that large layers of epoxy would just peal off. so instead I use mini cable ties at various points on the gearbox, so if it does crack it will still hold together, then I apply to any cracks with CA thin zap! But fiberglass cloth sounds like a great idea, Thanks!
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Old 06-26-2007, 06:30 PM
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Default RE: Lite machines TR gearbox defect

Quote:
ORIGINAL: FlyingFish

yea I saw that Helihobby has them, are all of BT's aluminum tailrotor gear boxes only designed to be used with belt drive conversion, or does BT make stock style gear boxes made of aluminum for stock wire drive.
I believe it can be used with both

Contact Matt at BT about that one

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Old 02-22-2009, 05:16 PM
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Default RE: Lite machines TR gearbox defect

There is a body filler that has fibreglass strands mixed in it sort of like bondo and fibreglass combined.Do you guys think that can work?
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Old 03-01-2009, 12:50 PM
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Default RE: Lite machines TR gearbox defect

Zap Ca for plastic and some fiberglass cloth works. You can wrap the entire gearbox in the glass cloth (2 oz cloth worth good). put the CA on the gear box wrap in the glass cloth. put some more CA on the cloth.
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Old 03-01-2009, 01:44 PM
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Default RE: Lite machines TR gearbox defect

Is it only the outer casing of the gear box that cracks?Are the internal components OK or is there signs that the gears are curling on the edges away from the direction of rotation? The gears will try to force themselves apart and a little slop will amplify the problem that much more.I will be getting mine this week and if there is room I'm going to make a thick "L" shaped aluminum bracket attach one end to the input side of the gear box with a small metal clamp and screws or machine screws and attach the other end to the output side of the gear box in the same way.By doing this it should give it the strength of four plastic gear boxes not as tough as metal but this should work.Do you have any aftermarket gear boxes kicking around? I have a little machine shop(hobby size) maybe I can do something with it,perhaps I could buy it from you.
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Old 03-01-2009, 10:50 PM
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Default RE: Lite machines TR gearbox defect

maybe a tiny hose clamp can keep it all together as well, but i have had tail rotor gear boxes blow up and fly apart in mid flight, not fun! So if you see small cracks in the tail rotor gear box, dont ignore them, they look like nothing but can spread under preassure during flight! [&:]
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Old 03-02-2009, 10:18 PM
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Default RE: Lite machines TR gearbox defect

I'll keep a look out for cracks when I get it before the first flight.Thanks. Jim
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Old 03-04-2009, 07:08 PM
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Default RE: Lite machines TR gearbox defect

OK I have my 120 but I see no cracks.My question now is where do they like to start cracking? What area do they start to develop cracks? I am going to take it all apart and rebuild the whole heli I noticed up and down movement on the main rotor shaft and that makes for very unstable operation so it's rebuild time any tips?
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Old 03-11-2009, 03:07 PM
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Default RE: Lite machines TR gearbox defect

What damage is done when the tail rotor gear box blows up?
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Old 03-11-2009, 04:12 PM
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Default RE: Lite machines TR gearbox defect

The entire gear box Blew apart, sending the tail rotor flying off in another direction, in turn causing the the whole Helicopter to spin out of control and crashing to the ground. And the good old corona 120 sustained no damage through all that, excepted for the tail rotor gearbox, I had then replaced the gearbox and was up and flying again in 20 minutes!
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Old 03-12-2009, 12:19 AM
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Default RE: Lite machines TR gearbox defect

I ordered some parts out of Edmonton but it looks like they are getting rid of thier stock,who do you normally deal with?
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Old 03-12-2009, 09:42 AM
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Default RE: Lite machines TR gearbox defect

Check the 2 links below, they usually carry stock and I purchase parts from them all the time.


http://www.shopatron.com/index/113

http://www.helihobby.com/html/LMH1.html
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Old 03-24-2009, 09:15 PM
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Default RE: Lite machines TR gearbox defect

Ever since they changed the plastic alloy from the old white to black, they are very trouble free. Mine has been on for the last 6 yrs. and never given any trouble. I bought a spare one at the time and never used it. I bought my LMH 110 in 96 and still going strong. Converted it to electric around 2000 with a Himax motor. Tough old bird Glad to see they brought it back.
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Old 11-21-2009, 03:20 PM
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Default RE: Lite machines TR gearbox defect

I finally had to replace my gearbox this week after working for about 10 years... I had to get the new black style one as the white has been discontinued.. Fit over the boom was fine, I had to play with the mesh on the gears a bit but after a little fiddling they are fine.. I like the set screw instead of the bolt thru the side of the boom.. had to flip the boom around to get it to work....everything was fine after that... the original one had a glued on tail fin and developed cracks which led to an inflight failure... hard to land when the heli is spinning around in circles... all is well now and no damage to the heli at all other than another dent in the tail boom... adding to the collection...
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