Head slop on the trex 600

[bpgoa]

Just been servicing the head (blade gripbearings and dampers) on my trex 600 and noticed that the head slightly wobbles on the main shaft and the main shaft wobbles slightly in the main bearings. The main bearings only have about 20 flights and the bearings seem fine. The heli's never been crashed (that's jinxed it) and the main shaft is the one that came with the kit. Approximate 2 years old. It may have been like this since new but I've not noticed.

I guess the questions are

Is this normal?
Do I need to care?
If so, how do I need to fix it?

[waveydavey]

Sounds like you've got some play between the mast collar and the top bearing. It shouldn't wobble around either the main shaft or the had. I woudn't fly it without sorting it out.

[bpgoa]

The slop, and it's tiny, is side to side only. There is no up and down play at all. The collar is set correct.

The head block seems to rock, again only a tiny amount.

Nothing is loose. It feels like the main shaft is 0.05mm - 0.01mm undersized.

[Mart61]

Personally, for such a minor amount of play, I'd not worry about it, especially if this "defect" has no effect on the flight characteristics of the heli.

However, if it is bugging you, try changing the main shaft. It's a £5 fix after all.

[bpgoa]

Personally, for such a minorgio amount of play, I'd not worry about it, especially if this "defect" has no effect on the flight characteristics of the heli.

However, if it is bugging you, try changing the main shaft. It's a £5 fix after all.

Good point well made.

I will do that regardless. I guess I'm looking for everyones experience.

Time to get the digital callipers out and a visit to the LHS.

[Nick B]

Hi,did you have a helper to lock down the the mainshaft locking collar down,its a 4 handed job.Losen the 2 grub screws in the collar,get someone to pull upwards on the head while holding the heli down by the skids,while pushing down on the collar,tighten up the grub screws.Once done,take out one of the grub screws and add loctite,put back in then do the other one

[chris jones2.4]

i had this on a 600, i just tightened the main shaft bolt up alot and it sorted it

[Swashbuckler]

The original 600N had undersize main shafts, just buy a new pair, it will be all good then.

[pgkevet]

Just been servicing the head (blade gripbearings and dampers) on my trex 600 and noticed that the head slightly wobbles on the main shaft and the main shaft wobbles slightly in the main bearings. The main bearings only have about 20 flights and the bearings seem fine. The heli's never been crashed (that's jinxed it) and the main shaft is the one that came with the kit. Approximate 2 years old. It may have been like this since new but I've not noticed.

I guess the questions are

Is this normal?
Do I need to care?
If so, how do I need to fix it?

I've noticed a little head wobbly on some of my trexes too. One of the simpelst fixes is to really tighten up the top jesus bolt..get a good wrench on the nut. It's as if that slotting in the low headblock doesnlt close properly. Another simple fix is to spray coat the very top of the mainshaft with .well almost anything ..hair lacquer or paint or even coat with thin epoxy.. then when dry and if necessary cut it back with fine sandpaper.

You probbaly notice how easy align heads drop onto the mainshafts.

If it's slop in the bearings then the first thing is to swap them out for better bearings..since the cheapo align one's wear fast anyway.

Some heli-models advocate threadlock on shaft to main bearings..I've never had to do that but it is another option. While you;re at it replace and regrease you head tube/dampers and check/change grip bearings.

That combo of attention can remove all that slop completely... and leave you noticing the inherent slop in linkages, swash and mixer arms... how afr do you want to go?

I've also been thinking of sleeving the antirotation arm on my swash (not applicable if you have an a-arm) with silicone tube..there's a degree of side slop there too..

[Radbourne78]

I have a tiny amount of movement on mine, even after replacing the bearing. I've looked at other 600n's and they seem to be the same

[Nick B]

I've also been thinking of sleeving the antirotation arm on my swash (not applicable if you have an a-arm) with silicone tube..there's a degree of side slop there too..

Try a small,thin length of carbon rod expoxyed onto the anti rotation bracket down the slot,carefully done it can reduce the gap.

I also find the Quick uk washout base reduces slop on the headblock pins

[bpgoa]

Hi,did you have a helper to lock down the the mainshaft locking collar down,its a 4 handed job.Losen the 2 grub screws in the collar,get someone to pull upwards on the head while holding the heli down by the skids,while pushing down on the collar,tighten up the grub screws.Once done,take out one of the grub screws and add loctite,put back in then do the other one

Hey. Thanks foe the advise but it's not loose.

[bpgoa]

i had this on a 600, i just tightened the main shaft bolt up alot and it sorted it

Will try this.

[bpgoa]

The original 600N had undersize main shafts, just buy a new pair, it will be all good then.

Will try this second

[Mslater]

I've also been thinking of sleeving the antirotation arm on my swash (not applicable if you have an a-arm) with silicone tube..there's a degree of side slop there too..

Not enough to worry about, it's fractions of a degree and I probably would not risk jamming the elevator.