t-rex 600 dominator Toque Tube Gear Failure

[450 heli]

Hey guys,

My front torque tube gears failed for the second time on my relatively new t-rex 600 dominator. I was trying to do a inverted tail in hurricane which I was around half way through when my tail started to kick out and then all of a sudden spun out and lost control which resulted in a 2-300 dollar crash. I had this happen but it was binding in a sharper right turn andI knew not to do that again. But this was unexpected. I installed the new gear set with the beveled front gear flush to the holder which eliminated binding as well as the rear torque tube gears. Do I want to have the gears closer to where they bind ever so slightly? Any aftermarket mods. I am by no means a pro flyer but would like to try to learn new maneuvers but don't have a lot of confidence in this unit.

Any mod suggestions, after market parts. Does too high a head speed make any difference. I have no governor on it right now and my throttle curve is set to 100 on stunt 2 which is what I was flying.

Any 600 size helicopters with helical or better stronger torque tubes that are good for 3d? I only know align.

Thanks

[Smoggie]

It'a a VERY well known weakness with the Trex 600Pro / Dominator... check previous threads, for instance this one: https://www.helifreak.com/showthread.php?t=609488

The usual advice is to back off on governor gain (not applicable if you aren't using governor) and to shim the TT bevel gear so that it meshes without any slop.

Even then it's still a weak link but usually ok unless you fly very hard. Having 100% throttle may not help because very high tail RPM puts more load on the gears. If that's really significant i can't say for sure but guys who run high headspeeds seem to have more issues.

I'm unsure of what you mean about installing gears 'flush to the holder' because as standard the bevel gears can only go in one place, you need shims to make any adjustment.

[RC/DC_5000]

I'm no grandpa when it comes to headspeed.. but I think 2800 rpm (100%) throttle is a bit much for the 600. Its still a beast at 2500 rpm (90%) and gets better flight times and just easier on the parts.

That being said, a local pilot rips on his 600 at 100% throttle.. He has the 600mx though. The 750mx has a much meaner blade bite. But he just smacks it to death and it holds up to him. I've stripped the drive gear too.. but it shouldn't strip in a hurricane. Its not that weak. A hurricane is not a power lift move.

IMO, the 600L is all about collective management. You can fly it hard, you just have to be careful with the collective and know when to pop it.. and when to take it easy. The 750mx is just brutal with torque.

I'd rebuild, turn the throttle down to 90% and spend some time getting used to it. Inspecting the gears between flights. Making transitions smoother and not yanking the collective more than it can lift. The helicopter will actually perform better, be faster and get better flight times.

Turn your pitch down to 12 degrees as well. Trust me.. too much pitch can overload the tail and strip the gears. The 750mx will not stop twisting the drivetrain until it strips. And the blades can only scoop so much air before they get loaded down.

After stripping my drive gear in FFF. I have since reduced my collective pitch to 12*, and just learned to listen to helicopter and not overload it. That motor can certainly out fly that airframe. So you have to respect it as such.

[450 heli]

Hey guys,

Thanks for the great informed responses. I bought 0.1 mm shims to add to the front gear that goes in the holder to get a closer fit to the umbrella gear which then goes to the auto rotation. I am just going to shim that one gear for now.

I like your idea on the lower head speed. I was thinking about that myself. I think I will lower it to 90% and I was thinking back on my previous flights after I changed out the gears from the first time and have down some maneuvers up high now knowing what I was doing which could have definitely stressed those gears and may have just been on its way out. Hard to say. What should I look for when checking the gears in between flights to know if I should replaced them before they go out? Seemed like no warning.

So my gain I had to continue to drop to get the tail to stop wagging on sharper turns, but it would fly fine in forward flight. So my question is should you have your gain set to have a better hold in 3d maneuvers even if in certain maneuvers it wags or have it to just before it wags which it is now (but may not have as much holding power for more advanced maneuvers).

Thanks again!

[RC/DC_5000]

What FBL are you using? You should be able to get a solid tail hold without any wag using the Rudder I gain value. It is the holding the strength of the gyro. But yes, also get all the gains as high as possible without unwanted oscillations.

It does sound to me like your tail wagging might have beat up the front drive gear and perhaps caused it to fail in the funnel. But its really hard to say.

I use an LED flashlight to look at the front drive gear between flights. It will be very obvious when its taking a beating. The gears will have white powder and worse, deformed teeth. If you get the pitch and throttle set just right.. you should be able to fly it with very little of either.

And yes.. it still rips and is extremely high performing. Again, its all about collective management IMO. The 750mx is a light switch of torque. Which is good for it to lift straight up into the atmosphere... but bad for the gears who get turned by it.

[MGPTWEGB]

Make it belt drive !

easy change ! Love my 12s 600 belt drive ( and yes I'm using the twin arm updated tail case cut out for the belt )

[Smoggie]

Originally Posted by MGPTWEGB

Make it belt drive !

easy change ! Love my 12s 600 belt drive ( and yes I'm using the twin arm updated tail case cut out for the belt )

Any photos?

[badgravity]

I'm planning to switch from TT to belt also just to avoid inevitable
stripping gears or blowing out tail from low headspeed ...
crashing from technical failure is not fun when it can be avoided ...

[FiLazer88]

I almost just wish they upgraded the front tail gear set to metal. I have found some success with higher headspeed but my gears already have taken a beating from when I was running around 2300. I'm on my second set but my front gears have a noticeable carve into each of the bevel teeth. Also still gettting a slight tail wag on pitch pumps and tic tocs, possibly from weakened gears. It's not stopping me from doing 3d but I'm always compensating just a tad for the slight blowout. I hear that messing with the I gain will improve this but without the bluetooth module its tough to find exactly where it sits best at the field. Switching to the Ikon helped but hasn't completely fixed the tail twitch. I've never had much success with precomp.

[RC/DC_5000]

I dont know guys.. I think there's an answer to the torque tube gear problem. Trust me, I stripped a TT gear in flight too. But since dialing in my governor and gains... I've been smacking the 750mx to death on a very high governor gain.

The TT gears don't have so much as a white powder on them. Whereas they used to get chewed up pretty bad. I don't have any shims.. the helicopter is all stock.

[Ignatjev]

Here is upgrade for front gears http://www.ebay.com/itm/CopterX-CX60...-/171037106672

Next season planning to upgrade from trex500 to trex600, seems like a must have for a good 600?

[RC/DC_5000]

Where are the gears for that upgrade? Do you just use the stock gears? If you use the same gears.. its the same problem.

Anyway, I'm quite sure that 600 Pro/L does not need any upgrade if its setup perfectly and flown with precision on the collective.

I've been flying mine at 2500 with a governor gain of 17 in big air 3D and smack. The gears have held up fine since I first stripped them on a slight V curve.

I think there is one defining factor... and thats if you beat on the collective. If you're smooth and precise, it holds up fine. Forcing the collective wastes power and also really stresses out the tail. The helicopter has a ton of excess power. If you don't apply it precisely, I think it causes problems.

[FiLazer88]

Just had my first tail gear strip out today, I was doing piro circles, not even popping the collective. I think the gears had been worn enough from when i was testing it at different headspeeds and gains. Managed to hit throttle hold so the heli wasn't under power when it went in, but it was piroetting so fast that I couldn't stir enough to compensate and it flipped sideways, gonna be around 150 to fix if you include blades. Anyone know of a place to get thin shims that fit on the front gears? I was noticing that the slight wear I had before it stripped was only on the upper 2/3 of the gears, so I'm thinking my mesh wasn't tight enough. I'm more frustrated with Align by the day, if you're going to put a motor like that in your stock align kit, you'd think they would upgrade the parts to take it. The fact that there isn't any recommended specs for headspeeds and gains says a lot as well.

[FiLazer88]

Originally Posted by 450 heli

Hey guys,

Thanks for the great informed responses. I bought 0.1 mm shims to add to the front gear that goes in the holder to get a closer fit to the umbrella gear which then goes to the auto rotation. I am just going to shim that one gear for now.

I like your idea on the lower head speed. I was thinking about that myself. I think I will lower it to 90% and I was thinking back on my previous flights after I changed out the gears from the first time and have down some maneuvers up high now knowing what I was doing which could have definitely stressed those gears and may have just been on its way out. Hard to say. What should I look for when checking the gears in between flights to know if I should replaced them before they go out? Seemed like no warning.

So my gain I had to continue to drop to get the tail to stop wagging on sharper turns, but it would fly fine in forward flight. So my question is should you have your gain set to have a better hold in 3d maneuvers even if in certain maneuvers it wags or have it to just before it wags which it is now (but may not have as much holding power for more advanced maneuvers).

Thanks again!

Where did you find those shims? Also, where are you located in MI? Would be cool to meetup and checkout your setup sometime. Seems like were in the same boat with this helicopter.

[Smoggie]

I used '3racing' brand shims on mine. they come in packs of 0.1, 0.2 and 0.3mm thickness so you can get the perfect fit:
http://www.ebay.com/itm/3Racing-Stai...item51c4eb6f2c

It's the 12mm ID size you need.

[nabl74]

During my build of the 600L dominator I used 3racing stainless steel shim spacers to shim out my rotor blade holders (had about 0.2mm play) left right parallel with rotor blade holder

also used shim spacers on tail gears to get tight mesh.

Original poster - Do yourself a favour / especially if you have a few helis lying around and get yourself the 6 / 8 / 10 and 12mm packs (each come with 0.1 / 0.2 and 0.3 shims). Indispensible.