450 Tail twitch

[trainrider06]

I have an issue with my TRex 450 FB heli.
The tail twitches, not all the time, but it twitches.
I replaced the TT and boom on it, checked all the mechanical movement front to back on the tail and tail gears, it's smooth as silk! I have a Spartan Quark gyro on it, my gains have been adjusted down so far that now I am getting drift.....with the twitch...
Anyone have this happen before?

 

[murankar]

Yes on cheap tail gyros with align servos. If it's twitchy then something is sticking. Have you checked all the bearings from the servo all the way back? How is the push rod guides? How are the blade grip bearings? Right now I am just throwing stuff out there just as a brain storm.

 

[trainrider06]

I've used the Quark on 3 other heli's, and it's been a solid performer. I've been wondering if the tail servo might have an issue, have checked links all seem free moving, will go back over it all and see what I can find...

 

[murankar]

Is the tail shaft bent? This could cause that also.

 

[trainrider06]

Originally the fella that had it put two stop screws into the base of the shaft block to help lock the tail in so it wouldn't move I am reckoning, those screws in turn got into the TT shaft (my original thought as to why the twitch) replaced the TT and boom, still twitching of course...

 

[murankar]

This is a puzzler for me.

 

[trainrider06]

I just took main blades off left tail on held onto the tail brace and spoiled it up to full power....tail just sat there not moving a bit, watched the pitch slider, not a bit of movement. Am really beginning to wonder about the gyro.

 

[holtneil]

Hi Rodney check the tail blade grip bearings I had a strange one like yours and it was a bearing ,under load of flight the tail would kick every so often , The other reason could be a vibration from the main head , can you change the main blades with some spare ones just to try , as its a fb head make sure the fly bar paddles are 100% level with the FB frame

 

[Lee]

Check the servo gears.
You may have a broken tooth, thats catching at some points.

 

[trainrider06]

Ok Neil, and Lee will investigate......I sure hope its not a bearing, that'll mean more damn waiting on parts! This heli has been one big pain in the arse!!!!!!!!!!!!!

 

[trainrider06]

Ok here is the investigation so far of what has been turned up.............Took tail servo apart, inspected all gears checked out ok. Had a couple of spare tail grip assemblies, they worked fine when I took them off....tried them....still tickin. Tail shaft the pitch slider slides like greased snot on and seems to be no evidence of binding or bent shaft. My next step it trying my spare Quark, i will be very surprised if that is the culprit, because they seem to be very fine gyro's....but one never knows I reckon.
i am wondering about something though. I have a thick pad under the gyro. Wondering if that is affecting it??
After I replace the gyro, I'll replace the servo I guess.....after that, I don't know what to do.....

 

[D.O.G.]

When I have a twitching servo and I know that the gyro is just fine, my choice of repair is to get another servo. That's my opinion. I rather spend $30.00 on a new servo vs spend money fixing the heli because the tail servo finally went while flying.

 

[trainrider06]

I have tried just about everything, gyro, blade grips, TT shaft and boom, fixing to change out servo....this servo on it worked great before. From what I've read these 450's are nortorious for tail issues, mainly blade grips....
We'll see what a different servo does....

 

[trainrider06]

servo made no difference, i am at a loss now, just gonna put it up on the shelf regroup, don't know what else to do....

 

[D.O.G.]

I'm just throwing it out their but how about your ESC? If you have a spare one, try switching one out. Cant hurt.

 

[trainrider06]

Might as well, have replaced everything else just about....

 

[D.O.G.]

Sorry about that. Don't get disgusted. This hobby always keeps you guessing. That's one of the reason I like this hobby. It makes you use your mine and knowledge on how to figure out whats going wrong or went wrong. That's just what I think anyway. Hope that you solve your twitch. Good luck.

 

[heli-maniac]

Its looking like mechanical set up of the tail may not have just the right amout of pitch on the tail blades

 

[trainrider06]

That's what I keep thinking myself, after I get in pissed at this thing I'll go over the setup again I gues

 

[Lee]

The fastest and easiest way to get a more accurate answer, would be to post a video of the issue.
It may be easier for us to see whats the problem.