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WyDiablo · 06-21-2009, 12:08 PM

I completely rebiult the tail with eveything except the right and left tail case housing, I even replaced the tail blades with new ones. Today on the first test flight it has a very fast tail vib (The whole tail vibrates). I tighten to belt because it felt kinda losse at the time but no luck. I also replaced the main rortor blades and the fethering shaft, so I"m kinda runnig out of options. Any suggestions from the B-400 pros in here. Oh and the blades are balanced perfect on a bubble balancer. (DX6i, HS-65MG servos, Stock Gyro/tail equipment.

Thanks
WyDiablo

KidHeli · 06-21-2009, 12:25 PM

i have found that if the belt is too tight it will cause bad vibes. also check the bearings, if you put your finger on them and turn em they should feel smooth; if they feel like there is sand in there then replace them. also if you were setting up the tail and landed a little hard the slightes slap on the ground will put a slight bend in the tail rotor shaft and that could cause bad vibes.

WyDiablo · 06-21-2009, 02:09 PM

(EVERYTHING) in the tail is new except the right and left tail case housing. And the belt I think is not tight at all.

WyDiablo

Starcraft-IX · 06-21-2009, 03:03 PM

Have you tried replacing the tail rotor drive shaft? It is the shaft that is driven from the lower main gear and hooks to the belt. I have a slight vibe that I'm chasing, and I am in the middle of changing that shaft. I've been told that rear rotor strikes can bend it. Seems odd, but there have been several folks that said it fixed the problem

WyDiablo · 06-21-2009, 05:12 PM

I never thought about that drive shaft, but I did remove my new tail baldes and spooled up the heli holding it in my hand and most of the vibs stopped and then affter removing my new rotor blades it looked as though it did not have any vibs period. The new blades were extremely hard to balance out. I"m wondering if they both weight the same, i don't any way to weight them so right now its just a guess. Its a vert sweet bird to fly when everything is working normal.

WyDiablo

BradMorris64 · 06-21-2009, 05:16 PM

As has been mentioned. It's most likely the tail rotor shaft is slightly bent. At least that's what caused that in mine.

blindpilot · 06-21-2009, 06:58 PM

I havd a vib and it turned out to be the main blades I had the alighn 325 black and yellow blades brand new the balenced good but gove a nasty tail vib if you got the black and yellow everyone says those are junk i now got the black and white wooden ones and that's good no more tail vib

mkane05 · 06-24-2009, 06:03 PM

I have the same problem with my 400. I have replaced almost every part on this heli, and I still get the vibration. I am going to try the drive pully as this is one of the few parts I havnt replaced.

ingrahal · 06-24-2009, 08:48 PM

Quote:

Originally Posted by WyDiablo

(EVERYTHING) in the tail is new except the right and left tail case housing. And the belt I think is not tight at all.

WyDiablo

Sometimes main rotor or drive vibes show up in the tail. The tail boom is long and amplifies the movement. Also the Boom braces transfer the vibes to the tail. You may be working on the wrong end.

Sounds like you definitely need to do a good balance on the main blades. CG and matching the weight.

Watch finless's video
http://video.helifreak.com/?subpath=...lancing101.wmv

Seebodener · 06-25-2009, 01:09 AM

Quote:

Originally Posted by ingrahal

... Sometimes main rotor or drive vibes show up in the tail. The tail boom is long and amplifies the movement. Also the Boom braces transfer the vibes to the tail. You may be working on the wrong end...

I found the vib´s on my Blade were causd by a bad, wobbling main-gear.
I took off main blades + tail blades, spooled it up slowly and by looking at the heli the main gear was woobbling => vib´s at the tail. As I increased speed => increased vib´s .
Changed main gear => almost no vib´s.

meatbob · 06-25-2009, 06:42 AM

I obsessed over this problem for a while. I tried rebalancing the main blades, replacing all of the tail parts, etc. I had a vibe so bad that it wrinkled the boom where it attached to the frame, because it would vibrate loose, and I would keep tightening it. I found that when I stopped using the E-flite woodies, my tail vibes diminished dramatically. I use either the Align 335 Pro Woodies or the HeliDirect FRP 325 ($6.40/pair!).

Make sure that you are not tightening the tail case down too tight in the back. There should be a little gap on the aft end of the tail case. I keep this gap consistent by sliding a washer (one of the feathering shaft washers) into the gap to keep it open.

I still have a slight vibe on my horizontal fin. I've just learned to live with it; dozens of flights and it has not degraded my flights at all.

WyDiablo · 06-25-2009, 06:57 AM

Well I have completey repalced everything in the tail section except for the right and left tail case housing. I replaced the main gear with one-way bearing. I removed my tail blades and some of the vibs stopped and then I removed my main blades and I almost have no vibs at all. As far as balancing the main blades they came out dead on but I did have to put a lot my balancing tape on the blades than I normaly have ever done. So I"m going to replace the (new) main blades and tail blades with some (New) blades to see if the first ones were causing the problem. I"m also going to replace the tail drive assembly that runs off the main gear. Wish me luck on finding the vib problem. But right now I"m trying to get my 450SE into the air. I'll keep you guys psoted.

WyDiablo

KidHeli · 06-25-2009, 09:04 AM

Quote:

Originally Posted by WyDiablo

Well I have completey repalced everything in the tail section except for the right and left tail case housing. I replaced the main gear with one-way bearing. I removed my tail blades and some of the vibs stopped and then I removed my main blades and I almost have no vibs at all. As far as balancing the main blades they came out dead on but I did have to put a lot my balancing tape on the blades than I normaly have ever done. So I"m going to replace the (new) main blades and tail blades with some (New) blades to see if the first ones were causing the problem. I"m also going to replace the tail drive assembly that runs off the main gear. Wish me luck on finding the vib problem. But right now I"m trying to get my 450SE into the air. I'll keep you guys psoted.

WyDiablo

hey man good luck, but i think you are on the right track. keep us posted

scnsaracer · 06-25-2009, 10:13 AM

I am so glad to find this thread. I have a blade 400 that is a year and a half old with about 150 flights and has never been crashed. I figured it was about time for a rebuild and bought all the eflight alum parts and the carbon boom and tore her down and put it all back together. Long story short I had a very strange vibration issue. Although everything was balanced perfectly the vibration was bad enought that the tail shaft would bend randomly and therefore the bird was unflyable. I worked and worked to no avail and eventually put it aside in frustration and my lovely wife "allowed" me to buy a trex500. After the experice of building my 500 (thanks Finless, you rock!

) I decided to pick the 400 up again and see if I could figure out the issue. The issue ended up being the bearing in the alum tail drive block, the inner race was the wrong size. Don't know why I didn't notice this before

. Put the stock one back on she was as smooth as ever. I was planning on selling the bird (no takers on here BTW) but it is flying so good now Im keeping it. In fact I installed the new Eflight upgrade motor yesterday and it is much more powerful now. Still not near as powerful the the 500 but I really enjoy flying this little guy so he will remain in the fleet.

Lesson learned: The tail assembly spins at 10,000 plus RPM so even the slightest issue will cause vibration.

WyDiablo · 06-28-2009, 05:48 PM

I have replaced the tail shaft, main rotor blades, tail drive/pully shaft, tail blades and bearings in the tail and main shaft bearings. I still have some vibs but nothing like before. I did notice something today after putting the boom back into the boom block and tighting the belt. I took the heli out to fly and after a couple of mins I checked the belt and it was so loose that I was slipping. That might be causing whats left of the vibs that I'm having.

Thanks
WyDiablo

blindpilot · 06-28-2009, 06:38 PM

the frame where tail boom tightens up the wholes stripped out on me one time causing a tail vib and boom keep sliding in and loosen the belt I put a bolt and nut fixed it works fine now hope this helps

06-21-2009, 12:08 PM	#1 (permalink)
WyDiablo Registered Users My HF Map location Join Date: May 2008	B-400 fast tail vibs I completely rebiult the tail with eveything except the right and left tail case housing, I even replaced the tail blades with new ones. Today on the first test flight it has a very fast tail vib (The whole tail vibrates). I tighten to belt because it felt kinda losse at the time but no luck. I also replaced the main rortor blades and the fethering shaft, so I"m kinda runnig out of options. Any suggestions from the B-400 pros in here. Oh and the blades are balanced perfect on a bubble balancer. (DX6i, HS-65MG servos, Stock Gyro/tail equipment. Thanks WyDiablo

06-25-2009, 06:42 AM	#11 (permalink)
meatbob Registered Users My HF Map location Join Date: Sep 2008	I obsessed over this problem for a while. I tried rebalancing the main blades, replacing all of the tail parts, etc. I had a vibe so bad that it wrinkled the boom where it attached to the frame, because it would vibrate loose, and I would keep tightening it. I found that when I stopped using the E-flite woodies, my tail vibes diminished dramatically. I use either the Align 335 Pro Woodies or the HeliDirect FRP 325 ($6.40/pair!). Make sure that you are not tightening the tail case down too tight in the back. There should be a little gap on the aft end of the tail case. I keep this gap consistent by sliding a washer (one of the feathering shaft washers) into the gap to keep it open. I still have a slight vibe on my horizontal fin. I've just learned to live with it; dozens of flights and it has not degraded my flights at all. __________________ Logo 500 SK720, 4025-890, CC ICE 100 T-Rex 600 ESP w/3G - 12S, 4025-630, CC ICE 80HV Blade 400 w/ HS5065MG, CopterX FBL, ICE Lite 50 eRaptor Conversion, 12S, 4035-500, JR 8700g, 3xDS610s

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06-21-2009, 12:25 PM	#2 (permalink)
KidHeli Registered Users My HF Map location Join Date: Feb 2009	i have found that if the belt is too tight it will cause bad vibes. also check the bearings, if you put your finger on them and turn em they should feel smooth; if they feel like there is sand in there then replace them. also if you were setting up the tail and landed a little hard the slightes slap on the ground will put a slight bend in the tail rotor shaft and that could cause bad vibes.

06-21-2009, 02:09 PM	#3 (permalink)
WyDiablo Registered Users Thread Starter My HF Map location Join Date: May 2008	(EVERYTHING) in the tail is new except the right and left tail case housing. And the belt I think is not tight at all. WyDiablo

06-21-2009, 03:03 PM	#4 (permalink)
Starcraft-IX Registered Users Join Date: Mar 2007	Have you tried replacing the tail rotor drive shaft? It is the shaft that is driven from the lower main gear and hooks to the belt. I have a slight vibe that I'm chasing, and I am in the middle of changing that shaft. I've been told that rear rotor strikes can bend it. Seems odd, but there have been several folks that said it fixed the problem

06-21-2009, 05:12 PM	#5 (permalink)
WyDiablo Registered Users Thread Starter My HF Map location Join Date: May 2008	I never thought about that drive shaft, but I did remove my new tail baldes and spooled up the heli holding it in my hand and most of the vibs stopped and then affter removing my new rotor blades it looked as though it did not have any vibs period. The new blades were extremely hard to balance out. I"m wondering if they both weight the same, i don't any way to weight them so right now its just a guess. Its a vert sweet bird to fly when everything is working normal. WyDiablo

06-21-2009, 05:16 PM	#6 (permalink)
BradMorris64 Registered Users Join Date: Jan 2009	As has been mentioned. It's most likely the tail rotor shaft is slightly bent. At least that's what caused that in mine.

06-21-2009, 06:58 PM	#7 (permalink)
blindpilot Registered Users Join Date: Apr 2009	I havd a vib and it turned out to be the main blades I had the alighn 325 black and yellow blades brand new the balenced good but gove a nasty tail vib if you got the black and yellow everyone says those are junk i now got the black and white wooden ones and that's good no more tail vib

06-24-2009, 06:03 PM	#8 (permalink)
mkane05 Registered Users Join Date: Jul 2008	I have the same problem with my 400. I have replaced almost every part on this heli, and I still get the vibration. I am going to try the drive pully as this is one of the few parts I havnt replaced.

06-25-2009, 06:57 AM	#12 (permalink)
WyDiablo Registered Users Thread Starter My HF Map location Join Date: May 2008	Well I have completey repalced everything in the tail section except for the right and left tail case housing. I replaced the main gear with one-way bearing. I removed my tail blades and some of the vibs stopped and then I removed my main blades and I almost have no vibs at all. As far as balancing the main blades they came out dead on but I did have to put a lot my balancing tape on the blades than I normaly have ever done. So I"m going to replace the (new) main blades and tail blades with some (New) blades to see if the first ones were causing the problem. I"m also going to replace the tail drive assembly that runs off the main gear. Wish me luck on finding the vib problem. But right now I"m trying to get my 450SE into the air. I'll keep you guys psoted. WyDiablo

06-25-2009, 10:13 AM	#14 (permalink)
scnsaracer Registered Users My HF Map location Join Date: Feb 2009	I am so glad to find this thread. I have a blade 400 that is a year and a half old with about 150 flights and has never been crashed. I figured it was about time for a rebuild and bought all the eflight alum parts and the carbon boom and tore her down and put it all back together. Long story short I had a very strange vibration issue. Although everything was balanced perfectly the vibration was bad enought that the tail shaft would bend randomly and therefore the bird was unflyable. I worked and worked to no avail and eventually put it aside in frustration and my lovely wife "allowed" me to buy a trex500. After the experice of building my 500 (thanks Finless, you rock! ) I decided to pick the 400 up again and see if I could figure out the issue. The issue ended up being the bearing in the alum tail drive block, the inner race was the wrong size. Don't know why I didn't notice this before . Put the stock one back on she was as smooth as ever. I was planning on selling the bird (no takers on here BTW) but it is flying so good now Im keeping it. In fact I installed the new Eflight upgrade motor yesterday and it is much more powerful now. Still not near as powerful the the 500 but I really enjoy flying this little guy so he will remain in the fleet. Lesson learned: The tail assembly spins at 10,000 plus RPM so even the slightest issue will cause vibration.

06-28-2009, 05:48 PM	#15 (permalink)
WyDiablo Registered Users Thread Starter My HF Map location Join Date: May 2008	I have replaced the tail shaft, main rotor blades, tail drive/pully shaft, tail blades and bearings in the tail and main shaft bearings. I still have some vibs but nothing like before. I did notice something today after putting the boom back into the boom block and tighting the belt. I took the heli out to fly and after a couple of mins I checked the belt and it was so loose that I was slipping. That might be causing whats left of the vibs that I'm having. Thanks WyDiablo

06-28-2009, 06:38 PM	#16 (permalink)
blindpilot Registered Users Join Date: Apr 2009	the frame where tail boom tightens up the wholes stripped out on me one time causing a tail vib and boom keep sliding in and loosen the belt I put a bolt and nut fixed it works fine now hope this helps

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