My Good/Bad experience with the new metal A gear.

[WBFAir]

Hello all


Well even though it was showing that my Horizon Hobby order that contained the metal gear as well as other things was to show up on Wednesday, surprise surprise, it came today.

Still have some Boca bearings coming and GenAces and a adapter from RC connecters so I don't even want to fly it much at least till the new bearings are in it, but as the gear came today, figured I see how things were to install it and considering all I found, I thought it would be helpful to others to do this report on it and sorry its really really long... but I might recommend reading through it if you are going to use this gear as there good points to tell, but some bad ones too that at least I found for me that I think are pretty important to note.

To start off, for the gears themselves in relation to each other size wise, and keep in mind, mine is a wiped out one, but still I figured I'd take some measurements and as far as I can tell, their just about exactly the same in all that matters (well more on that actually later). In by that I measured the OD of the flat gear sections and for me, I found them both to be 14.40 mm OD. For this I was mostly concerned about if it was going to hit the FET but mine seem to clear that before, so at least if it was the same, felt I should be ok.

As well I also measured from the bottom of one of screw holes to the top of the face of the gear and for me that seemed to be exactly the same too of about 5.80mm, but more on that later.

Next for the metal gear itself, it comes with two machine thread screws so its better then one, but at least as best as I could tell, the holes for the screws in the gear are not tapped. So for me I decided to screw one in each before the install as I figured it would be easier at that time to do the tapping then later in the bird and with trying to line up the holes. The using of the screws for the tapping seemed to go as expected.

So next I tried to install it by just removing the main shaft only and even leaving the B gear installed and I don't know if anyone else has or is going to be able to do this but for me while it looked like it should just be easy to do this, I tried it many times and just couldn't seem to be able to slip the gear in all the way to get it lined up so I could just slide the shaft back in and finally gave up and just split the frame.

So apart and with the B gear out of the way for some reason it lined up fine and so got it on the shaft and lined up the holes and put in one screw, then the second....and for some reason the second one was really tight (with all this fuse I guess I might not have put each screw I used for each side tapping in the very same one?)...anyway, figured I'd just keep screwing it in and let it do another tap and that's when the fun happened as the screw head just broke off and with the body of what was left just about flush with the gear.


Son of a friggen you know what.


Well took it all apart and spend the next half hour drilling out that little screw with my pin vise and was actually quite shocked as to how well I was able to get only the screw and not do any damage or odd stuff to the gears hole. Eventually and as I couldn't find a second screw that small, I did find a SS Hex head screw that was long so I just ran that one through and its really locked up good on the one side so I really feel it will be OK, (I did locktite it though as metal to metal).

* Now at this point of the story and this is kinda a big thing too, to go back to something I noticed before I even started to mess with drilling that screw out, if you recall I mentioned I did find the measurements from to gears hole to the top of it at least seem to be the same as the plastic, but once I had it together that first time, I saw that it must be actually a little smaller as for sure it gave me some up and down play.

I rechecked this play with the old gear when I finally got the metal one free of the shaft, and I can assure you I got it clean and that there was not damage done to the shaft. But for sure the metal one was just a little shorter but it really seemed to multiply once assembled and at least on mine, was not an acceptable amount.

For this I could well imagine it could let the shaft pop up and down and since this all translates to the main head grips, I think it could have really reduced how precisely the head pitch control would have worked.

Was also considering all the stuff where the FBL system reacts to things happening that are not inputs and with it having this much play, I could imagine bad things.

I also think with the B gear and other things, unless you look at it like I did, this play might not be seen when fully assembled so easily. But with having just the shaft, with the upper lock collar, then the bearing, then the gear, you really see how much play there is.

Anyway, I very much would recommend anyone replacing this gear with the metal one really look at this closely to see if theirs is the same.


So next to talk about what I did to fix this.

Was quite puzzled by how I was going to correct this and thought about some flat washers but the problem was, at least for the ones I had, any that were big enough ID wise to go over the shaft were then to big on the OD, and as the bearing is really inside the frame well where it sits, there just wasn't any way this would work.

In the end what I found worked was as I had some Align parts lying around, I had a extra one of the little spacer that goes on the feathering shaft between the blade grip and the head dampener of a Trex 450. And this little spacer was as about a perfect as could be ID wise to go over the main shaft as could be and really was not too wide OD wise at all and just sat nicely on the inner collar of the upper bearing alone like it needs to, and even still allowed access to the top of the bearing opening to oil it.

The only down side was that it was too thick to just fit it between the upper collar and the bearing for the play the new gear gave me. But, as there is a bit of a protruding section to the lower side of that plastic upper 130 collar, I just sanded that down until I removed enough to allow a perfect fit of the Align spacer between the two. Gave it just hair extra too for expansion.

So now the whole assembly was just perfect and nice and snug just as it should be with just a hair of play to ensure no binding and was putting the loads in all the right places and had no issues fitting back in the frame.

So next I finally got to getting the whole thing assembled to a point I could see how the A & B gear would work together and ran into my next fun discovery.

What I found was even though it didn't seem like it before with the plastic A gear, and for the life of me I'll be darned if I can see on the B gear why this is, none the less, there was some kind of bad spot on the B gear with just one of its teeth and I really confirmed this as I marked the gear on that one tooth and now with the A gear being metal I could tell how every time it came around to this tooth in the B gear, there was a good stop of nice free spinning and click to get over it.

So all in all...is this what wiped out my plastic A gear so bad and so fast ???

Just to mention, I actually did notice something almost similar after the first two flights of the helo. With this though I was sure it was a spot on the A gear as it was only happening in the exact same spot on it and at that spot, it looked like there was a little bit of bad molding. For this I fixed it by going at it with a tiny flat head to just clear out the gap and seemed to have fixed it as I did get it to stop.

But now kinda unsure, maybe this was from this B gear?

Anyway, as I have a HobbyTown USA about 5 min from me, I jumped in the car and they had just gotten their first shipment of 130X parts about 4 hours before and had one bag of the gearset that has the B gear.

I went home and installed it and like magic, the click was gone.

So did a good soak of the gears in Sullivan's and put the rest of the helo together while continually making sure everything stayed smooth as I went and set up the backlash for a nice comfortable fit.

Just by spinning by hand the helo's TT system was severely nice and smooth and the first flight was perfect and even the tail vib at full RPM I had seems to be gone. Although it was just one flight test so far.

At this point I still seem to have the transition vib and so I want to get the Boca bearings in there before I put any miles on it but I'm pretty optimistic at least for this A gear issue, that I have things working where I shouldn't have any more problems.

Oh and btw, I played a little with making sure the gear is missing my front boards FET's by when I finally had the metal A gear all straighten out and still had the frame split, I put some pressure on the board to see how close I was to the gear, and while it is close, I know for now it is not touching and even has a space to play with.

So again, sorry this was so long but I figured to include everything in case all or part of it could be of some help to others.

So to wrap this up...

1: If your gonna go with the metal gear I highly recommend you be sure the play between the gear, the bearing and the upper collar are not too much.

Of course I never flew mine with the play I had, and it might have even been sorta OK, but I think to have it with no play is much better.

2: If you had your plastic A gear wiped out quickly, might want to see if you have any weirdness from the B gear with the new A and if so, try a new B and see how that goes.

3: Am hoping this is not the case for others but you might have to do a full frame split to install this new gear.

Well again, hope that is all of some help to others.

Just herd the charger go off so I think I'll go give it one more flight before bed to be sure I'm not eating all these words.

[Lompma]

Good to know. I have a metal one coming also. What Align 450 ring/part are you talking about? The spacer between the dampener and the bearing? I have alot of 450 parts laying around.

[WBFAir]

Originally Posted by Lompma

Good to know. I have a metal one coming also. What Align 450 ring/part are you talking about? The spacer between the dampener and the bearing? I have alot of 450 parts laying around.

Yup, the off silver one that comes if you buy a Feathering shaft. PN: HS1251

One I use is probably from my SE head, sorry didn't think to measure it.

Was just checking and that one is listed as being 1.5mm wide (or tall as it might be said)

Then just checked and the one for the Pro and Sport shaft PN: H450102A is listed as 1.0mm.

Perhaps if you had the Pro one, might not need to take as much off the 130's collar.

[itsmillertime0]

tl;dr. Just kidding, thanks for sharing.

[GSPI]

I will be looking at that later today when I install the metal gear. Thanks again for your effort in posting.

[WBFAir]

Just a little update.

Apparently though I thought it was taken care of at least somewhat in a side effect kind of thing from what I did in the work of the gear replacement maybe, my tail is actually vibrating just as much as before.

Have noticed on this that RPM's play a big part and once I tried a really good fresh pack this morning, at the 85% throttle level a full voltge pack gave me, the tail was shaking bad.

Dropped it % down to 75 and it took quite a bit out.

Am very much thinking (well actually hoping) that the Boca flange bearings I have coming for the TR shaft will take care of this.

Btw I did put a brand new set of the Yellow tail blades on prior to this while I was doing all the other work, so could be out of balance too but for sure not from being damaged.

[so-fly]

Originally Posted by WBFAir

Just a little update.

Apparently though I thought it was taken care of at least somewhat in a side effect kind of thing from what I did in the work of the gear replacement maybe, my tail is actually vibrating just as much as before.

Have noticed on this that RPM's play a big part and once I tried a really good fresh pack this morning, at the 85% throttle level a full voltge pack gave me, the tail was shaking bad.

Dropped it % down to 75 and it took quite a bit out.

Am very much thinking (well actually hoping) that the Boca flange bearings I have coming for the TR shaft will take care of this.

Btw I did put a brand new set of the Yellow tail blades on prior to this while I was doing all the other work, so could be out of balance too but for sure not from being damaged.

If you have stock bearings in the tail set the blades really loose, it'll help reduce the violent vibration at certain rpms

[WBFAir]

Yeah I was almost wondering if that might help as I have played with the tensions thinking I'd get better control and less drifting without the blades being so loose, which it does I think, but was wondering if that also was making this vib worse.

Basically have been running them just snug enough to still let them flop freely like they were out of the box, but just enough for that.

Will try running them a little looser to see how that goes till I get the new bearings.

Thanks

[whodothevoodoo]

Originally Posted by WBFAir

Just a little update.

Apparently though I thought it was taken care of at least somewhat in a side effect kind of thing from what I did in the work of the gear replacement maybe, my tail is actually vibrating just as much as before.

Btw I did put a brand new set of the Yellow tail blades on prior to this while I was doing all the other work, so could be out of balance too but for sure not from being damaged.

I would bet that the new tail blades are off balance. Balancing any rotating mass is very important to smooth helicopter operation.

Thanks for the posting and the length is just about right. Be thankful you haven't had to read some of my rants.

[TTRAPTOR903D]

Thanks for the post. Do you happen to have the part #s for the Boca bearings that you ordered?

[GSPI]

Originally Posted by whodothevoodoo

I would bet that the new tail blades are off balance. Balancing any rotating mass is very important to smooth helicopter operation.

Thanks for the posting and the length is just about right. Be thankful you haven't had to read some of my rants.

That is a very good idea as I calculated the torque tube to be running 9000+ rpm based on estimated head speeds and any tail imbalance will cause issues. Good bearings help too!

We'll get this thing figured out...