450 Please help with this trex 450 pro vibration issue... Please!

coolgabsi

Super Mod & DEAL KING!
Man. I replaced every freaking gear shaft , bearing on it. New everything. I am so frustrated. Low head rpm doesnt show it.. But idle up 85 percent throttle or up as you can see in the video goes crazy... Tail fin , carbon boom supports, tail push rod all go crazy!!!!!!! Blades are tracking.

I am stuck!! Help!!!

http://www.youtube.com/watch?v=l0OyWyK_7pQ
 

Tony

Staff member
Have you tried lowering the gains on the gyro (ele and ail)? And what is the exact weight of each blade (in grams) as well as the cog of each blade?
 

coolgabsi

Super Mod & DEAL KING!
The gyro wouldn't make the fin vibrate. I can lower the gains if you like. But they are very low now.

:(

I'll get the weight of the blades soon.
 

murankar

Staff member
Tail rotor shaft? did you check this part out to see if it is bent. The last time I had vibrations like that the tail rotor shaft was bent. Who knows it might be ever so slight that low rpms may not show it.
 

coolgabsi

Super Mod & DEAL KING!
murankar... I did replace that also.. I took the blades off ans spooled on the bench to check for bent shafts.. seemed fine..

tony
the more I think of it, the more I wanna change the gyro settings. People said that D gain on my gyro being too high might cause it also. I always had it on this setting, but who knows it might have changed a bit. anywaz. i'll look into it.

One more question, the gyro wires going from RX to gyro (three wires) are all tied together.. that is making them a pretty hard mass and they are close to the frame as there is only so much wire that can go there, so could this be normal vibes coming to the gyro too much??? cause I did rewire it to clean up the mess I had before.


?? :\
 

Lee

Well-Known Member
Did you replace the boom like i said? Or even just moving it slightly. I'm sure its a resonant frequency vibe.
 

murankar

Staff member
Your tail blades are off by a small bit. Would that cause that issue? Plus is the cog the same for each of those, does that not matter on the tail?
 

coolgabsi

Super Mod & DEAL KING!
it does.. one blade as you can see is on a stable "S" sign on my weighing scale and the other one is not cause it was flipping between 2.19 and 2.20... its less than a .01 gm error. any change i wanna do it will make it worse.. so i gotta let it be. I havent cg'd them yet, but without them i had the same issue, so I hardly believe its anything to do with that anymore :(
 

murankar

Staff member
I would say bent. Those looked like carbon fiber in the second video. Are the tt powder coated?


You maybe stuck on rolling it on glass to fund out for sure.
 

Tony

Staff member
The tail spins so fast that .01g is not going to matter. All of my responses were put into your videos. Let me know.

- - - Updated - - -

And the TT is carbon for the new Pro V2's.
 

coolgabsi

Super Mod & DEAL KING!
Hey guys! This is my find in the last flight... Vibrations were to a minimum, but the bird was shaking still. I thought that this is not getting fixed.

Then I thought of doing punch outs, loops and rolls with it... The vibration goes away as soon as the head loads up. I punch it there is no vibe... I am coming out of a loop it's straight as an arrow, and the head unloads or it gets around hover point inverted or right side up, and man it shook again.

Took the D gain down on my tarot zyx from 30 to 15 and I gain down from 100 to 90 on both my elevator and ailerons.

No change...

But how does this work? Loading of head makes the shakes go away... My mcpx v2 did the exact same thing on vibrations.. But I just went to v1 and that fixed it. Lol I don't have that option here :)

Can someone shed some light? :)
 

murankar

Staff member
Wish I had some input for ya. The only thing I can think of is harmonic vibrations, but those would go away just prior to lift off i presume. Correct me if I am wrong. This reminds me of is a top. A top will be super solid at faster rpms, but as it slows down it starts to shake and not spin in a perfect circle.

This baffles my limited knowledge of helicopters.

maybe it's something in the air frame that id causing the gyro to get vibrated or maybe the foam tape used on the gyro is not good enough.

I have not a clue, just throwing some ideas out there to see if I can spark some ideas about other solutions.
 

coolgabsi

Super Mod & DEAL KING!
just thinking out loud .. I did think that the dampeners in my head are really hard.. the dfc head comes with hard dampeners. now i am not saying that is the reason.. but it might be... idle up on higher head speed.. i see that shaking.. or vibration.. may be dampeneing the head a little might help ?? what do y'all think ?


gyro tape.. I have a futaba tape... on top of that i have a metal plate.. and on top i have a spectrum gyro tape which is thicker.. and then my gyro.. i think that is ok.... ? what do you say ? :/
 

murankar

Staff member
Did this start after the DFC upgrade? if so then maybe try a slightly softer dampener and see what happens.
 

coolgabsi

Super Mod & DEAL KING!
I just read that people threw away the pastic dampeners right off once they got the DFC head.. and put TRUEBLOOD or KBDD in it.. interesting.. hey .. I might be getting somewhere.. :)
 

Tony

Staff member
I had a whole long post written out since you pretty much got on your knees and begged me to get on here lol. But then the battery died without warning on my lappy and I lost it all lmao. Oh well, here is the condensed version.

I would not replace the dampers with KBDD, they are just as hard as the ones you have now. If you are wanting softer, then go with teh stock v2 Pro Align dampers. But if your blade tracking is perfect, then this is not your issue.

Your heli is talking to you and you need to listen to what it has to say. I think you just answered your own question with your post above. You said "when under a load, the vibration quits". Your answer is in that statement. I will pause here so you have time to think about this....
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Did you get the answer yet? Well I have.

It's one of two things. Either it's the links have a lot of play in them, or there is something wrong with one of the servos. I would suggest putting in 3 new digital cyclic servos. I will almost guarantee this will fix your issue. the "load makes it stop" is your answer. If it was the gyro, then loading it up would more than likely make it worse. If you have to, put 3 mg90s servos in there or EXI D213F servos to test. However, because I have used then, and they work better than expected, the DS-410's are the way to go. They were rock solid on my Pro V2. Hope this helps.
 
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