Trex 250 pro DFC main gear drive does not turn the Torque Tube Front Drive

[MGPTWEGB]

The HK T5 star or Torx screws are fantastic.

Ah Yes me like too

You can fix any 250 TT problem with a Belt .

[guyguerra]

Lahannsven, don't give up on the 250 yet. There has been a lot of good advice in this thread, examples:
1: This is not a good beginner machine.
2: Good hex wrenches are critical and WILL stop the stripping if you dont over crank them.
3: Your gear mesh problem is unusual and from my experience of owning 3 of these, and the fellow posters here, we haven't seen this problem before (other than being caused by a stripped drive gear).
4: It is such a prevalent problem to have the top umbrella gear strip loose of the drive shaft that many people end up converting to belts. I haven't, but I always pull the umbrella gear off and apply super glue then push it back on. If this method fails me someday, I will go to the belt also.

All that said, these quirky machines are a lot of fun when you finally get settled down with them. I do a lot of aerobatics with mine. Maybe put it to the side till your ready to fiddle with it and enjoy the challenge instead of being frustrated. That's what I had to do. There are several other machines in that size that are easier to maintain. I would think the Blade 300CF might be a good choice for you right now.

[skunkworx]

I agree. I wish I could post a video of how well mine flies. I spent a month or so carefully putting it together after a complete tear-down, and it was totally worth it. I think a belted tail and the HK screws may help; both are inexpensive and work great. But also having good electronics seems to make a very massive difference in the way they fly as well.
After coming from a 130X, I can first-handedly say that this is the only micro that holds up to the promise of flying like a 'real' heli (450-700 class), so it sucks to hear you're having so many issues with it. Maybe just put it away for a little while and revisit it someday, or simply take your time getting it perfected and see if your opinion changes over time?

I wish I lived closer because I'd gladly rebuild it for you. I like mine so much I've already started assembling a 2nd and 3rd airframe which would be an impossiblility if it didn't fly well. I simply don't keep crappy machines around and the 250 is definitely much better than the horror stories always made them out to be.

[thepiper92]

Is there a definite fix for the front torque tube gears. Had one strip off, tried adding two flats on the shafts, and used "pins" through the gear to hold it on, then adding glue. It stripped again, however, after a crash when my feather shaft snapped mid flight (may have been weakened from a previous dumb thumb moment). Now I tried two part 5 minute epoxy and it will not hold at all. I am getting new gears in, but will epoxy on a fresh set hold the umbrella gear from any risk of stripping off during flight?

BTW, MIP 0.9mm is the way to go. Seems like it won't fit, but use another driver at first, get the screws fairly snug and then give some pressure with the MIP driver and it will pop right into the screws, almost no chance for stripping.

[guyguerra]

I have 2 of these helis. One I built and one I bought used. The used one is very upgraded (MKS servos, Viper motor, YGE ESC, KDE aluminum plates). It is a torque tube and I never have a problem with it. The one I built was always stripping gears, and like you, I tried everything. In November I switched it over to a belt drive, along with changing to MKS servos and putting a Talon ESC in it, and I am really happy I did. I don't know why the used one has such a good tail drive gear in it, but I'm happy with both of them. There is no difference in the way they fly, but a belt is much less trouble than stripped gears on the torque tube.

As far as MIP wrenches go, I think they are a must for these small screws. Sometimes the MIP won't fit where the Align wrench will, so it's worth having both, but MIP's are way better tools.

[thepiper92]

Originally Posted by guyguerra

I have 2 of these helis. One I built and one I bought used. The used one is very upgraded (MKS servos, Viper motor, YGE ESC, KDE aluminum plates). It is a torque tube and I never have a problem with it. The one I built was always stripping gears, and like you, I tried everything. In November I switched it over to a belt drive, along with changing to MKS servos and putting a Talon ESC in it, and I am really happy I did. I don't know why the used one has such a good tail drive gear in it, but I'm happy with both of them. There is no difference in the way they fly, but a belt is much less trouble than stripped gears on the torque tube.

As far as MIP wrenches go, I think they are a must for these small screws. Sometimes the MIP won't fit where the Align wrench will, so it's worth having both, but MIP's are way better tools.

I really like the TT more, to be honest...even though there is this one issue. I had belts on two 450 helis, and I hated setting the tension, and one belt snapping on the HK450. It was also annoying getting the belt through the boom. Do you know if Loctite 609 damages plastics? I am thinking of using it on the umbrella gear.

[skunkworx]

609 holding compund is plastic safe. We used it a lot in the Fusion 50 for the TT bearings and tail boom casing.

As to belts/TTs, I definitely prefer belts. Once you've got the trick down to get it through the boom (fishing string or sewing thread and a paper clip) then it takes mere seconds to rethread one in; plus you don't have to tear open the back half of the machine to swap it out.

If setting the tension is a major pain then you're probably nuking it. I keep all of mine a little on the loose side and relatively 'close' is good enough depending on the machine. I admit Align uses the absolute worst tail belt setup the market has ever seen. But even they are still simple enough that as long as it's not skipping in flight then they really are set-and-forget. If they'd put a self-tensioner on it I'm pretty sure you'd really love the belts again.

With that said, I currently have more TT machines than belted, but they don't bother me nearly as much as they used to. I've come to grips with swapping gears because I enjoy the rest of the machine enough to where it's worth the hassle. Admittedly as well, it's nice to just drop the gear in and go.

[lahannsven]

Meanwhile some time has passed and I got some more experience with my Trex250 Pro DFC. First I changed my FBL to AR7200BX, which stabilizes it good. The front Torque Tube gear also was replaced and the new one is better fitting.

I put 4 positions for my gyro settings (transmitter DX9):

Pos1: 35%
Pos2: 30%
Pos3: 25%
Pos4: 20%

The DX9 gyro ranges from -100% to +100%. These settings are different on other transmitters.

So during the flight I can change my gyro settings according to tail wagging.

Also the Trex250 likes high speed flight. At high speed usually the vibrations disappear.

Alltogether the Trex450 is much easier to handle, but I can fly my 250 DFC now and it is my fastest heli.


Sven

[guyguerra]

Originally Posted by lahannsven

Meanwhile some time has passed and I got some more experience with my Trex250 Pro DFC. First I changed my FBL to AR7200BX, which stabilizes it good.

Sven

Can you tell me where you mounted the AR7200BX? I tried putting one in the bottom of the frame where they typically go, but the width of the fbl made it touch the frames on both sides. I had a vibration problem, which I am assuming is because of that.

[thepiper92]

Originally Posted by guyguerra

Can you tell me where you mounted the AR7200BX? I tried putting one in the bottom of the frame where they typically go, but the width of the fbl made it touch the frames on both sides. I had a vibration problem, which I am assuming is because of that.

Here whatcha do, stick a bit of foam tape on the AR7200BX, the somewhat firm stuff with adhesive on one side. It will rest right against the tail servo mount. Can still slide the servo mount in and out. Never had vibe issues.

[thepiper92]

Originally Posted by skunkworx

609 holding compund is plastic safe. We used it a lot in the Fusion 50 for the TT bearings and tail boom casing.

As to belts/TTs, I definitely prefer belts. Once you've got the trick down to get it through the boom (fishing string or sewing thread and a paper clip) then it takes mere seconds to rethread one in; plus you don't have to tear open the back half of the machine to swap it out.

If setting the tension is a major pain then you're probably nuking it. I keep all of mine a little on the loose side and relatively 'close' is good enough depending on the machine. I admit Align uses the absolute worst tail belt setup the market has ever seen. But even they are still simple enough that as long as it's not skipping in flight then they really are set-and-forget. If they'd put a self-tensioner on it I'm pretty sure you'd really love the belts again.

With that said, I currently have more TT machines than belted, but they don't bother me nearly as much as they used to. I've come to grips with swapping gears because I enjoy the rest of the machine enough to where it's worth the hassle. Admittedly as well, it's nice to just drop the gear in and go.

So it doesn't cause brittleness of plastic and it actually cures? Well that's my answer then,
If it holds a smooth pinion in a smooth shaft, it will hold that gear on.

[Murph_d]

Originally Posted by guyguerra

Can you tell me where you mounted the AR7200BX? I tried putting one in the bottom of the frame where they typically go, but the width of the fbl made it touch the frames on both sides. I had a vibration problem, which I am assuming is because of that.

I've had mine mounted vertically on the side frame for about a year and a half. Just a narrow strip of double sided mounting tape at the front and rear to avoid the bolt heads and plastic protrusions. Very accessible, flies great and stays put. I wouldn't consider putting it anywhere else. I even side mounted it on my 300x and my Gaui X2. I love that I can see the gyro light while flying because sometimes I forget to switch to heading-hold mode.

[Murph_d]

Originally Posted by thepiper92

I Do you know if Loctite 609 damages plastics? I am thinking of using it on the umbrella gear.

This is from the Henkel Loctite 609 product page:

This product is not normally recommended for use on plastics
(particularly thermoplastic materials where stress cracking of
the plastic could result). Users are recommended to confirm
compatibility of the product with such substrates.

When the TT version first came out, there was a lot of discussion on this forum about what adhesive to use. You could do a search but as I recall, epoxy and JB Weld were favored.

This is the thread I was thinking of:
Trex 250 Pro DFC, Torque Tube Front Drive Gear (H25131) gets loose!!

[thepiper92]

Originally Posted by Murph_d

This is from the Henkel Loctite 609 product page:


When the TT version first came out, there was a lot of discussion on this forum about what adhesive to use. You could do a search but as I recall, epoxy and JB Weld were favored.

This is the thread I was thinking of:
Trex 250 Pro DFC, Torque Tube Front Drive Gear (H25131) gets loose!!

Is there anyway to know if the gear will be harmed by it. I'm worried 5 minute epoxy won't be good enough, it certain isn't holding that well.

[lahannsven]

Hi guyguerra,

I mounted the AR7200BX vertical on the right side. I was inspired by the video of pilot: Dave Beach on Youtube. He made several videos. Just type in "Trex250 AR7200BX Dave Beach".


The AR7200BX is really much better than the 3GX. It already includes the receiver.

For the gyro settings you can assign two switches on the DX9 for the gyro channel.


Sven

[thepiper92]

Originally Posted by lahannsven

Hi guyguerra,

I mounted the AR7200BX vertical on the right side. I was inspired by the video of pilot: Dave Beach on Youtube. He made several videos. Just type in "Trex250 AR7200BX Dave Beach".


The AR7200BX is really much better than the 3GX. It already includes the receiver.

For the gyro settings you can assign two switches on the DX9 for the gyro channel.


Sven

What does a switch for the gyro do? I just use a pot on my 9xr for gyo, right past mid is HH, left is rate.

[guyguerra]

Hi lahannsven, I also ran into the same thing of not being able to fit the FBL inside the frame. I ended up putting a bavarian Demon on the side very similar to your AR7200BX. Heres a link with some pictures.
https://www.helifreak.com/showthread.php?t=678364

thepiper92, I believe the gyro switches he mentioned are for your idle ups to have different gyro gains on each head speed.

[lahannsven]

Hi guyguerra,

yes I'm very interested in the Bavarian Demon 3SX. This year I plan a Trex550 DFC project with the 3SX. Maybe I'll try the 3SX first on a smaller heli, because I read that there have been some terrible failures.

The setup of the rescue button is obviusly not that easy.
I saw that you have as transmitter the spektrum DX9. Could you send me a complete DX9 transmitter setup for the Bavarian Demon. Do you connect over the DSMX satellite ?

Sven

[guyguerra]

Hi Sven, the Demon is a great FBL imho.. I have one on my Logo 800, Logo 700, Whiplash 700e, Logo 690 and the Trex 250. I am also in the process of putting one in my Goblin 570, and have setup 3 others for friends.It is very simple to setup, though as with most units the first one can be more challenging. It's no more challenging than any other FBL that you set up for the first time.
The setup of the bail out is also simple. Theres a word definition that can confuse you. They call the Self Leveling Mode "Rigid", and call the bail out mode "Horizon".
I will be glad to send you my DX9 file and a popular link thats on this site by Yosimite that I use.
I would put it on your most expensive heli first to help cut down wrecks and repair expenses. I won't tie up this thread on the Demon, and there is a lot published, but please feel free to PM me to ask any setup questions. Theres a very experienced guy called "popokatepetl" on the Demon thread and I follow his threads for good info. I always use Spectrum receivers on my Demons as I don't trust the Demon compatibility, though the 250 is Sats direct to the Demon to save weight.
As to the 250, I am starting to see threads that talk about a Microbeast Pro that has a bailout. It looks taller than normal but the same width. If so, we just need to see if theres enough vertical distance in the body to fit it. I still prefer computer screens when I do a set up as opposed to lights, but I have programmed many AR7200BX's and Microbeasts and been very happy.
Please PM me if you need help on a Demon, but check popokatepetl first.
Sorry if I got off topic, won't happen again.