300X - the HOW TO GET RID OF VIBRATIONS tread

[SHYguy]

OK guys, I think it's time we gathered all the info on this subject. And as we know this particular heli is one that can easily get troublesome vibrations.

Let this be a FAQ and troubleshooting tread for this problem only.

OK, just to get started:

1) Use CF blades if you want to run higher HS. Especially if you upgrade the motor or gear up (over the stock motor on 9T). The woodies can cause vibrations.

2) Don't over tighten the stock plastic tail case.

3) Use aluminium pulley in stead of plastic in the tail case.

4) Balance the main blades

5) Balance the whole tail rotor. Take it off and do it in a balancing tool or do the "dynamic balancing" (trial and error).

6) Upgrade to a CNC'ed main gear from Lynx or MicroHeli. The stock ones are out of round always (it varies how much), as they are cast.

7) Do the motor Loctite mod (or else the shaft will slip inside the bearings > vibrations)

8) Tail pitch slider mod & better tail hub:
https://www.helifreak.com/showthread.php?t=543119

After a crash, always check main shaft and feathering shaft:

Take off the head, slowly spool ut and watch:
[ame]http://youtu.be/T_3JE91RhQk[/ame]
-this one does not look OK

[ame]http://youtu.be/gV5rykiI-YU[/ame]
-this one looks OK

How to check the spindle shaft:
[ame]http://youtu.be/IHzRSi1nv6s[/ame]

If you do the "roll method" it's best if you have a glass plate to roll it on.

Keep em' coming guys!

[SHYguy]

Myself I have a "new vibe" on one of my 300X helis that I've never come across before

When seen from the side if tips back and forth, on the elevator axis. It does this in 100% IU, not in normal mode (lower HS). Main and spindle shaft is fine.

Anyone else had this? I've repalaced the main shaft, spindle shaft, new Lynx gear with OWB, CF blades are balanced and never crashed, tried a new motor. I wonder if it can be bent head or grips? If not it must be something related to the tail... slightly bent tail shaft maybe?

EDIT: One of my carbon tail blades disintegrated mid flight, so I'm hoping this was the cause. Probably a crack I did not see... Strange thing was that it flew ok'ish in normal mode with only 1 tail blade. In IU it was shaking like mad of course. Higher HS = more vibe problems

[Nelsonisms]

Originally Posted by SHYguy

Myself I have a "new vibe" on one of my 300X helis that I've never come across before

When seen from the side if tips back and forth, on the elevator axis. It does this in 100% IU, not in normal mode (lower HS). Main and spindle shaft is fine.

Anyone else had this? I've repalaced the main shaft, spindle shaft, new Lynx gear with OWB, CF blades are balanced and never crashed, tried a new motor. I wonder if it can be bent head or grips? If not it must be something related to the tail... slightly bent tail shaft maybe?

My guess would be something related to Dial #1 (cyclic gain) and/or your head dampeners. I'm not sure if you're using them or not, but I know I saw some similar issues when I installed the Lynx Ultra Dampeners. I switched back to the stock dampeners and all is well. I think it's possible I wasn't running enough headspeed for the Lynx dampeners. (3200 RPM governed at that time)

From the tuning guide (Head/Cyclic Tuning section)...

6. Bring heli into a hover for about 5 seconds. Any oscillation, shudder, or wobling in the head then lower Dial #1 in small increments until it's gone. Note: If your tail is bobbing up and down then make sure you're running enough headspeed for your head dampers. Increase if needed.

[SHYguy]

Thx! I've used the Lynx dampeners for a good while, no issues. I also use the iKON.

I'll replace more parts and see...

It's ok at low HS (normal mode), not high HS (IU 100%)

[eltreato]

Thanks for starting this thread SHY, I will be referring to it as I work to eliminate a persistent vibe when hovering at higher head speeds.

Can you elaborate on point 2 about the overtightened tail case? I haven't touched mine since new, but am curious how a tail case that's tight on the boom could contribute to vibes.

Thanks again!

[SHYguy]

Originally Posted by eltreato

Thanks for starting this thread SHY, I will be referring to it as I work to eliminate a persistent vibe when hovering at higher head speeds.

Can you elaborate on point 2 about the overtightened tail case? I haven't touched mine since new, but am curious how a tail case that's tight on the boom could contribute to vibes.

Thanks again!

No worries mate!

Never did this myself, I've just seen others state this many times. I'm sure some other HF can elaborate...

[Nelsonisms]

Originally Posted by eltreato

Thanks for starting this thread SHY, I will be referring to it as I work to eliminate a persistent vibe when hovering at higher head speeds.

Can you elaborate on point 2 about the overtightened tail case? I haven't touched mine since new, but am curious how a tail case that's tight on the boom could contribute to vibes.

Thanks again!

The idea is that it's possible to overtighten the screws in the plastic tail case (including the screws that hold the fin on) such that it's enough to actually warp or twist it in such a way that it causes the bearing holding the shaft on one side to become slightly off-centered thereby inducing a vibration in the tail. So the general recommendation is to tighten the screws down enough that they are just snug and not go beyond that. Blade/Horizon has a similar recommendation when discussing the screws in the plastic frame as well.

[eltreato]

Great info, thanks guys.

[obi1cannoli]

also pull the eflite sticker off the main motor as it doesn't wrap all the way around the motor and could possibly cause some harmonic vibrations

[bmlasater]

fwiw..

Spinning the heli up in your hand can be very instructive...This IS dangerous, but will help with all sorts ov vibes associated with the t/r.....I swap blades, use tape, loosen or tighten screws till I have it as smooth as possible...Then mount main blades and repeat....The Beast will do all sorts of odd things if subjected to vibes...

John.

[SHYguy]

Originally Posted by bmlasater

fwiw..

Spinning the heli up in your hand can be very instructive...This IS dangerous, but will help with all sorts ov vibes associated with the t/r.....I swap blades, use tape, loosen or tighten screws till I have it as smooth as possible...Then mount main blades and repeat....The Beast will do all sorts of odd things if subjected to vibes...

John.

I'd recommend doing that without the main blades. Just balance them properly and they will be perfect. With those off it's not that dangerous anymore

[copenhagen]

Thought my main blades were "good enough". Replaced feather and main shafts and was about to replace the hub and tried a different set of blades- fixed the problem. Apparently the Carbon Fibers that blade used to make came in balanced sets and you can't just interchange them. Yes I know I could balance them.

[SHYguy]

Originally Posted by copenhagen

Thought my main blades were "good enough". Replaced feather and main shafts and was about to replace the hub and tried a different set of blades- fixed the problem. Apparently the Carbon Fibers that blade used to make came in balanced sets and you can't just interchange them. Yes I know I could balance them.

Not at all! My last set was almost balanced. The previous ones were very far off! >> Always check & balance!

[copenhagen]

Originally Posted by SHYguy

Not at all! My last set was almost balanced. The previous ones were very far off! >> Always check & balance!

I've been through 4 sets and it wasn't until I mixed and matched that I had a vibration issue.

[SHYguy]

Originally Posted by SHYguy

EDIT: One of my carbon tail blades disintegrated mid flight, so I'm hoping this was the cause. Probably a crack I did not see... Strange thing was that it flew ok'ish in normal mode with only 1 tail blade. In IU it was shaking like mad of course. Higher HS = more vibe problems

Nah! With new tail blades still no good... ok in normal mode, but shook like crazy now in IU!

So I did some checks:
-bearing for main shaft seem ok
-found a small crack in the frame
-but most of all, the belt seems too worn. Also the rear alu pulley







Still, the shakes were so crazy I'm really wondering if this alone could be causing it?

The anti rotation pin jumped out two times (how is that even possible?)! Skids looked like a mix master! Could have whipped cream with'em!

[jcmo]

Originally Posted by SHYguy

Nah! With new tail blades still no good... ok in normal mode, but shook like crazy now in IU!

So I did some checks:
-bearing for main shaft seem ok
-found a small crack in the frame
-but most of all, the belt seems too worn. Also the rear alu pulley

*Attachments Omitted*

Still, the shakes were so crazy I'm really wondering if this alone could be causing it?

The anti rotation pin jumped out two times (how is that even possible?)! Skids looked like a mix master! Could have whipped cream with'em!

You have REALLY run that thing through its paces. I had not considered the aluminum tail pulley before, but seeing that makes me wonder how long I should expect my stock tail pulley to last... Great pics! Please let us know if your vibrations get better

[Keymaker]

Originally Posted by SHYguy

Myself I have a "new vibe" on one of my 300X helis that I've never come across before

When seen from the side if tips back and forth, on the elevator axis. It does this in 100% IU, not in normal mode (lower HS). Main and spindle shaft is fine.

Anyone else had this? I've repalaced the main shaft, spindle shaft, new Lynx gear with OWB, CF blades are balanced and never crashed, tried a new motor. I wonder if it can be bent head or grips? If not it must be something related to the tail... slightly bent tail shaft maybe?

EDIT: One of my carbon tail blades disintegrated mid flight, so I'm hoping this was the cause. Probably a crack I did not see... Strange thing was that it flew ok'ish in normal mode with only 1 tail blade. In IU it was shaking like mad of course. Higher HS = more vibe problems

I'll say your tail case bearings are bad, you will be surprise how crazy your tail gets when one of them runs dry. You won't be able to see if they're bad by just spinning the tail blades so its just best to change them out if you haven't been using oil on them. They're only about $4 for both of them. People sometimes think that their tail case is too tight when in fact the problem is do to bad bearings in the case and preasure being release bit. If you have a plastic case the problem goes away if you loose the screws a bit but on a aluminum case that won't work so the bearings need to be change.

[SHYguy]

Hmmm... this is getting weirder and weirder...

New belt, alu tail pulley, fixed the frame... At first: Yes! No vibes, also in IU 100%. Then there's a muted sound like "WHOP!" - then it shakes like crazy. Landed, inspected, couldn't see anything obvious. The front/back vibes I had before is gone though. Now it's just a "stable shake" if that makes any sense

I reduced IU to 85% which helped a bit, but the shakes come and go...

OK so I need to try and sway the head and grips... doesn't seem to be tail related now.

Still, very very curios as to what that sound is! And before I had the anti-rotation pin jump out of the guide, WTF!

Maybe I should do a full teardown... Just wish I had a Lynx DFC head and frame ready...

[Tim Wolff]

I'm fixing to do a full teardown on mine. My IU TC is flat 85% and I have a loud and very visible vibration that comes and goes. Snugged everything up. Loosened the tail case screws. Tightened/loosened the belt. etc. Fine for flight or two and buzzin' like hornet's nest the next. Replaced the tail hub and grips with a Align 450 setup and thought I had it licked. Flew great yesterday morning. 8 hours later and it started buzzin' and shakin' as soon as I switched to IU.

Started flying both my 300x and 450x at the same time and the 450x has been quiet, smooth, and reliable and the 300x has been giving me trouble.

[SHYguy]

Considering Boca bearings...