Vertical Play on mainshaft

[FlamingHomer]

Hello Guys,

I have a little vertical play in the mainshaft. the heli has 10 flights on it.
The 12mm shim on the lower bearing block is mounted and all screws are tight. i measured the shim is a 12mm and its 1.5mm thick. do i need a 2mm shim or its another trick to kill the play in the shaft.

Greetings from switzerland.

Christian

[Mike Spano]

are you sure the shim is 1.5mm thick? I believe they are 1mm thick, and mine was tight to get in at 1mm thick.

I am sure you have done this, but check your head, be sure the head itself is tight and the play you are feeling is not the head.

other than that, if all main shaft bearing blocks are tight and thrust bearing retainers are tight, other than that, we will have to check things one at a time.

maybe posting some pics would help too.

[FlamingHomer]

Sorry, its 0.5mm. The play is definitly in the Mainshaft. I can see it moving on the upper bearing block. Thrust bearings are tigh too. Maybe i can shoot some fotos this evening.
Thank u

[Mike Spano]

yea, .5, sorry, I goofed that up too.

ok, try to take a few pics.

did you install both of the delrin shims? the black ones that go on top and under the main gear on the auto sleeve?

that .5mm shim should have been pretty tight to get slid under everything, was it?

[FlamingHomer]

Hi again,

The play is not much. The shim slips very tight under the maingear-unit. Today i was at my local heli-shop. Hes Synergy distributor for switzerland and he told me i can fly with no problems.
I check it after every flight and tell u if i get a problem with it!

Thanks alot

Greets chris

[Mike Spano]

yes, you can fly it without an issue. if it is small, no problem. if its not, we need to look at the build and see where its happening. if the shim was a tight fit, then no play at all should be there. check Jesus bolt.

[rcnut]

If memory serves...just loosen the bottom bearing block and push it back up. My 766 developed a slight up/down mainshaft play after 13 flights. I caulk it up to break-in. As I'm getting used to this new feel, I keep upping the cyclic control response to my likings...and decreasing the expo.

[Charles Rosario]

My solution was to pull the 4M shouldered bolt and rotate the main drive 180 degrees relative to the main shaft. The 4M bolt was harder to fully seat and that took out the play in the main shaft.   Otherwise moving the bottom bearing block up and then installing the 4M bolt is a good alternative.