anyone have vibration problems on their b400? I bought new mainshaft and tail blades but it seems to have a sort of harmonic vibration at like 75% throttle. almost seems like it is the drive gear(?) when I rotate it slow I see a slight wobble in the lower of the two anyone else seeing this?

Did you balance your main rotor blade, its usually the cause of most problems. To test remove the blades and see if there are any vibs, then balance blade like the the following info http://www.helihobby.com/html/balancing_blades.html. Let us know if this solves your problems as it did mine.

Mine is back at Horizon right now for the same issue. It had a bad high speed vibration just before hover. The horizontal tail fin would vibrate so bad it looked like it was an inch wide. I tried the main, spindle, tail shaft and both blades with no luck. The final was the gyro quit on me.
It has been at Horizon over 2 weeks. I have called many times and don't get to far. "We are very busy"....Etc
I finally called a manager and complained that I have over $500 in this with the parts I tried. They got it to a tech and he called and said he needs thr radio and battery........B.S............Horizon doesn't have a DX6i or a battery to test it with.
The first guy I spoke to said to just send the heli........
It is on the bench waiting to get worked on as we speak..........

Enough complaining

If your blades aren't tracking right that could cause it. Wrong gear mesh.

Mine vibrates really bad untill the head speed comes up and then it goes away I tried everything I even put a new gyro (futaba 401) on it and it still vibrates like an epileptic once in the air its fine. Mine came straight from the box with a bent feathering shaft so I can understand everyones frustration.[:@]

my vibration can be seen in the tail fins bad, I am going to take off the tail blades hold it and see if it is still there.

Your blade grips probably aren't tighten the same amount on both sides. And the blades are trying to find the right spot until it comes up to speed. It is not a bad thing. Anoying but nothing to worry about.

Mine was very smooth until just before hover. It is not a wobble like blade balance or tracking. It is a high speed vibration that most likely comes from a fast moving part (motor, tail...etc). Kind of like a buzz. I tried with the blades off with no luck. It really sucks when you can't find the problem. I got rid of my last Rex cause of a glitch issue. I thought awesome....2.4... no more unfindable problems..

[sm=bananahead.gif][sm=bananahead.gif][sm=bananahead.gif]
Yea right

Hey thanks karbonI did not know that I guess you learn something new everyday!!

I mean thanks evdreamer

I found that the main shaft and feathering shaft really bends easily, even with a "soft" blade strike. I am especially surprised at how wimpy the feathering shaft is. It looks like its the same size a the one in the CPP. Fortunately, they are both easy to straighten. I like how it only takes a minute to get the main shaft out and you do not have to take the whole heli apart to do it. When MicroHeli comes out with the hardened replacements, I will defiitely get them as I did for my CPP.

Any blade strike will bend the feathering shaft and agree they are the same as the belt cp. Initially I had vibrations, remove the blades and run it up, if it smooth then most likely the blades needs balancing, the stock blades were not balanced [] but still flew well, agree tracking is very important, specially at higher head speed

There are only a few things that can cause vibration...

Bent feathering shaft (sometimes you can tell its bent)
Blades are off track
Main shaft bent (sometimes you cant tell its bent)
Blades are out of balance
Flybar is not balanced, straight or incorrect angle on the pads.
Loose belt.

fw190 do you know what causes the belts to shred I at times go thru alot of belts on my trex. All seems fine and then im in flight and then there goes the neighborhood I just thought someone might have some insight on this I know we are in the blade forum but it still is a concern for me because the blade has a belt and a belt shredding is never far from my mind while I flying.

Had over 50 flights on my B400 and belt still looks good. I might change it when i get to around 100. 100 flights deserves a new belt

Having too tight on the belt can cause the belt to tear or shred, tough on the pulley bearings too. As long as when compressing the belt near the gear pulley if they don't reach half way to the other side of the belt its too tight if they touch its too loose they can rub on each other in the boom. Says so on the B400 instruction.

How many flights do you get before the belt goes out?

Well I appreciate your insight I would say that I get like 10-25 flights maybe. It has not happend on the blade 400 but my rex has had it happen 3-4 times and it is just frustrating beacause all I worry about the whole flight is that belt shredding. Also on your B400 do you get a build up of belt material on the guide wheel on the tail mine has some black from the belt almost like a skid mark? just curious while we are on the subject ? So belt tension should be about half way when compressed just near the gear? Thanks for your insight.[sm=50_50.gif]

Any tips on how to judge or measure that halfway point?
I have a hard time guesstimating how far the belt is compressing.