[vgjunky]

Stripped the main gear in my TREX 600. Ordered new ones from Rotoquest. Installed it (put the small screws in, took them out to get rid of the extra little bits of plastic from when you initially screw into the plastic of the main gear), and there seems to be a 1mm different as the main gear rotates. I ran the heli up in the yard and as soon as it spools up and slight variation in the main disappears and it everything runs straight and smooth. I checked the second main (they come in a pack of 2), placed it on a perfectly flat glass surface, and it's not perfect either, but close to it. Is that normal? All screws are set at the same pressure, I was careful of that. Like I said it's a very small variation, maybe 1mm.

Thoughts, opinions?

[hifly2104]

Originally Posted by vgjunky

Stripped the main gear in my TREX 600. Ordered new ones from Rotoquest. Installed it (put the small screws in, took them out to get rid of the extra little bits of plastic from when you initially screw into the plastic of the main gear), and there seems to be a 1mm different as the main gear rotates. I ran the heli up in the yard and as soon as it spools up and slight variation in the main disappears and it everything runs straight and smooth. I checked the second main (they come in a pack of 2), placed it on a perfectly flat glass surface, and it's not perfect either, but close to it. Is that normal? All screws are set at the same pressure, I was careful of that. Like I said it's a very small variation, maybe 1mm.

Thoughts, opinions?

Probably warpage from manufacturing Heat from the molten plastic and cooling down

[Cougar429]

Very true. Don't forget these are mass produced, likely in plastic injection form. With that they are popped out of the mold and into a bin while still warm. Differences in cooling rates, loads imposed by resting position, (and anything dropped in above them) all contribute to warpage.

[suresharp]

Yes the gear wheels always seem to be a little out of true. Ihave tried boiling in hot water for 1 1/2 min and then lay on flat surface with weights on it =very little change. Tried to install hub with gear hot tighting the screws alternetly = a little better for the effort. When I heated up a lot longer and hotter it got worse even with weight on it. Hard to change mem of plastic. Over all running result = not a large contributor to vibs But if worp is bad then wear on bearing and other parts are going to wear out quicker

[Keyrigger]

So far, I have been fairly lucky, and not had any that were warped bad enough to throw out. Most have been very good with the only real bad gears being those on the smaller 450 size heli's. Even then, as long as they don't rub on the lower gear or mainframe, I would install them by evenly torquing the screws in like you would do a tire on a car. Don't overtighten them but make sure they are snug. Take care.

Don

[Max]

I have a 450 with a slightly twisted main gear- It does not seem to hamper performance at all.