Horizontal play in tail blade grips

[fuzzyllamma]

I have some play in both of my tail blade grips that wasnt fixed by taking them apart and retightening. I know that on my 450 pro that this usually means bad grip bearings but i checked all of the bearings and they move smoothly and dont feel notchy at all. I was wondering if i should just leave it well alone and this is normal, or shim them like i would main blade grips. I have shims from my rjx head from my 450 that would probably work. Should i worry about it or not?

[350Z_Al]

Are you tail blade grips black? There is a new tail blade grip assembly that with silver grips that have two radial bearings instead of one to eliminate most of the play.

[fuzzyllamma]

I have the silver ones they have 2 bearings plus the thrust bearings. In the manual, no shims or anything are mentioned

[fuzzyllamma]

Bump, i still need suggestions :/

[jones007]

By "horizontal play," do you mean along the axis of the retaining bolt? The thrust bearing only takes load in one direction (opposing centripetal acceleration), so there's really nothing else to prevent moving the holders inward toward the hub. Usually a bit of axial free-play is intentionally included for the radial bearing to prevent them from taking a thrust load. The only critical bit is that the blade holders need to be restrained at the same radius from the hub to ensure balance. As long as the retaining bolts are tight (and loctited), unless you have severe vibration, I wouldn't worry about it.My QUK and Kasama tails have a bit of axial play as well.

--Kevin

[fuzzyllamma]

Yes, what i mean by "play" is that i can pull on the blade grips and they will move back and forth as if the bolts weren't fully tightened (they are). I was just doing some other reading and i found that there is a thread where many others were talking about a spacer shim that is supposedly "forgotten" by align and to use a 450 pro main shaft shim inbetween the radial and thrust bearing. Should i just fly it, see if it wags and if it does, try adding the shim?

[jones007]

The other thread may have pointed out an issue worth checking. I never used the silver Align tail set, instead swapping it for the QUK unit from the start. The manual (page 15) shows the old unit that had just one radial bearing and one thrust bearing per holder, and the thrust bearing was supported by the holder, not the radial bearing. I believe they included a second radial baring in the silver blade holders, and depending on how they do this there can be a critical problem if a shim washer is missed, potentially causing the blade pitch to "freeze" at RPM. You likely cannot manual pull hard enough to make this happen, but in flight it can. We had a similar issue some 25 years ago with Schluter/Robbe helicopters.

The shim washer in the tail would serve the same purpose as the shim washer in the main blade holder shown at the top of page 5 in the manual. This makes sure that the thrust load is carried by the outer race of the radial bearing so that the inner race remains free. It might be worth taking apart the assembly to see what's in there. If the bearing setup is like the mains, you'll likely want a shim spacer between the thrust and outer radial. I'll check the unit I have at home later. If anyone has an exploded view of the 3-bearing holder, that might be useful.

--Kevin

[jones007]

take a look here:

http://www.align.com.tw/shop/product...oducts_id=4142

No exploded view, but the 3rd part in the list will be the shim washers. Make sure you have them.

--Kevin

[fuzzyllamma]

Well i took it all apart and put the shims from my 450 pro main shaft in and they fit the hub perfectly. The one side is perfect with no play at all. The other side has a very small amount of play that is very nominal to the amount it had before. I will run it like this and see what happens. If i have a tail wag in hover, ill know the first place to look. Thanks for input!