mx450 owners.

[Scottlclem]

I went over the head on Mx450 trying to get some of the slop out. It turns
out that almost all the slop was caused by the screws that go on each side of the flybar that have to be loose enough to let the flybar move but tight enough that there is no play or slop .
I put Zap blue thread lock on the 2 screws when I built the heli but they worked there way loose. This was causing my tracking problems with the main blades .I bought some Align 325mm woodies and the blade tracking was better but I could never get it right. These screws are so tiny that only a few threads hold so use RED thread lock.

Take one screw out, put the red thread lock on it and then put it back tightening it and moving the flybar up and down with you other hand at the same time ,when you start feeling the flybar binding or geting a little harder to move stop and back off just a touch. Do the same on the other screw. DO NOT GET IT TO TIGHT .

This fix will take out most of the slop in the head. Before I did this I could move the blade holders back and forth by hand and there was at least 1 or 2 degrees of play.There was no way to get the blades to track with all that slop.

[windbender]

hi Scott,
Is your center hub the one with the top-hat spacer on the screw or the one with the ball bearings?
tks
Wb

[L0stS0ul]

yeah the ball bearing CNC head will fix this problem. To bad the 450 does not come with that one out of the gate.

[Scottlclem]

Yes mine has the spacer.

[broncomech]

This problem seems to keep popping up over and over, I have had it with the new CNC mast with bearings as well as the older aluminum mast.
I think the problem starts with too short a screw which causes everything to get loose in a few flights because there is not enough thread engagement for the loctite to hang on to.
Here is my fix, remove the fly bar bearings and find a drill bit that will fit snugly in the hole that runs down the center of the fly bar. Assemble the flybar to the center mast with screws that thread through the inner wall of the flybar, then run the drill bit down the center to trim off the part of the screw that would cause the flybar to bind. Take it all back apart (just keep the screws on the same side they were installed in when drilled) clean out all the shavings, clean parts with alcohol or acetone to remove any oils that would weaken the loctite bond and reassemble with loctite(I use red as it holds up to oils better after assembly)
This provides maximum thread engagement and you can crank the screws down without binding the flybar.
It is a bit more of a pain to do this way but I haven't had a screw come loose for over 50 flights now.
If you have the early style/450 aluminum head you may need to add a shim washer (HMXE7361 ....4925-002 ....Flat Washer 2x3.5x0.2mm same one used on the mixing arms and levers) under each brass bushing to prevent binding.

[windbender]

Scott,
FWIW -I have a theory about this; I think that the flybar "looseness" on the MX is different from the requirements of a Trex. If you look at the videos or theads on the flybar setup (typically Trex), we are always told that it should be fairly loose. In the MX400 this leads to the tracking problems . Once you start to tighten the see-saw screws, the tracking gets a lot better and sometimes even goes away, but , on my heli , I've found that this ia at the expense of the cyclic resonse. As a result the see-saw spacer has to be oiled constantly or the cyclic (mostly roll) gradually fades. It will be great if this is the real fix for this poblem, there have been a ton of treads where a blade tracks higher or lower because of a single turn of the links to the blade.

Lostsoul,
With the 'ball bearing' center hub, is the flybar loose like the one on Finless' Maintainence video?

Wb

[broncomech]

With the 'ball bearing' center hub, is the flybar loose like the one on Finless' Maintainence video?

I am running a Helimax ball bearing center mast with a flybar that it is as free as the Trex in the Finless video with no tracking problems at all. I had all sorts of tracking issues until I figured out how to keep the screws tight.

[Scottlclem]

The flybar screws worked there way lose again :dontknow I am going to try Broncomech's fix . I think will try putting on the thread loc then drilling the screws . It's possible you won't be able to get them in the correct position ( drilling them out will make them half round on the ends) so getting them right then drilling seems to be the best move..

[broncomech]

getting them right then drilling seems to be the best move..




Good idea just make sure you clean everything well to remove any trace of oil before you loctite it and blow any chips out with compressed air before the bearings go back in and it should work fine.