Add shims to front TT Horz umbrella gear???

[WBFAir]

Hello all

I actually have kind of a mix of the older Sport TT conversion kit and a ProV2 TT boom/tail gear block and front TT assembly (and rest of helo for that matter).

The helo seems to be flying fine but I do notice that there is a fair amount of play for the TT drive.

In other words, in grabbing the tail and rotating it back and forth while holding the main gear, I get about a 1/8 or little less of backlash play that in looking, I can see that the source of this play is coming from the front TT umbrella gears.

So for one, was just wondering......is this normal?

Again, the helo seems to flying fine but am just wondering if I should use some of these: http://www.ac-rc.com/product_info.ph...u2ctalopnnmno3 to take up this slack, or just leave it alone

One thing I was almost wondering about as I oddly for no reason I wiped out a set of these gear back when this conversion tail was on a SE (IE different boom/tail block and gear ass) was if this clearance isn't needed maybe? Am wondering if maybe after a fair amount of use on a real hot day, does the plastic expand a little and if you take out all the backlash, will it seize up and destroy itself?

Thanks for any help.

[robbancs]

These shims are rather meant for the tail I think so you can get rid of pitch slop.
In the front it doesn't matter too much because under load it just works fine. In fact, for the same reason, I'm not entirely convinced that using them on the back gear is necessary.

With all that said, if you've got so much play, there may not be enough grip in the front and may strip easier than necessary. Adding one or two shims there may be justified. Just don't overdo it because it'll bind and make your motor struggle unnecessarily.

[WBFAir]

Thanks for the info

I think the front and back gear body's are the same OD though right.

Shim's would fit either one correct?

[WBFAir]

Originally Posted by robbancs

With all that said, if you've got so much play, there may not be enough grip in the front and may strip easier than necessary. Adding one or two shims there may be justified. Just don't overdo it because it'll bind and make your motor struggle unnecessarily.

Yeah, as I mentioned, I did have the front gears go on me one time.

It was really weird and I really never for sure found out why but several years ago when I had this setup on a 450 SE V2 and I had been flying it for a month or so, it got towards the end of the season so I wanted to store the packs but I also didn't have a device to bring them down to 50%. So I was watching some football one day and decided to take off the main blades and just run the packs out on the helo with it sitting on the floor.

I left the tail blades on but trust me, there was no torque on the helo so there was no load.

So I ran one pack down and it took about 10 min, then I ran a second one and in about 3 min, all of a sudden I herd a quick build up of a whining noise and as I was sitting next to it with the Rx right there, I shut it down quick, but in checking it over I found that both of the front umbrella gears were completely wiped out.

In taking a look at the Castle ESC report, I could see the low amperage through the first pack and the same on the second one up to a point and then in a really short time, it climbed up very quickly so obviously something got bound up on it.

Again, I never really did find out why all this happened, I did replace the drive set bearings but I would really be surprised that those were the issue as they seemed perfectly fine. As well as all since the conversion I never had one single crash on the helo. At any rate I did change them on the outside chance.

All in all, I really think that it had something to do with running the helo for so long on the Gov speed of about 3100 and without any air being blown down into the front gears as given how they just both were completely wiped clean and in such a short time, I really think that they might have gotten hot and probably expanded and bound up and that is what was the cause of all of it.

After I replaced the gears and like I said, those bearings and for the whole rest of the next year, I never had a problem.

But with all that, it makes me wonder about going to tight with this backlash.

Also I should mention one other odd thing is that my 700E, which is completely out of the box stock for all these parts, has a fair amount of backlash play too.

Guess in the end I was wondering if this play is normal, and or if anyone has ever installed these shims and seen any issues from them.