bad vibration developing

[crfiddy]

bought b400 4-27-08. 50 flights so far, decided to finally use idle up. when the rotor speed increases there is excessive rotor vibration so bad that it almost shook off the canopy. this heli has NEVER been crashed or had any hard landings. mainly sport flying no 3d. any thoughts would be greatly appreciated.

[jimzpsd]

I'm no expert here, but make sure the fly bar paddles are level. Then check for proper blade tracking while at pitch, and make sure the blades are balanced. The process of elimination should find the flaw.

[eugenefelisco]

I had that thread a while back. I changed everything tail blades,bearings,tail shaft,pulley and boom. But it didn't help I then change the belt and whooola like magic its gone. The excessive sliding of the belt cause the uneven teeth and the vibration came from it.

Please check belt and tension it properly.

[sokal]

i agree with belt tention to much and too loos will cause vibe

also it seem the ball links that connect from the washout arms to flybars seem to wear fast at the flybar end

check security every so offten mine last about 50 flights or so an i too put much stress on the rotor even with out 3d

[crfiddy]

I replaced the dampers, cleaned and lubed all bearing and bushings on the rotor.
didnt check the tail or belt thanks for the direction guys really appreciate it.
well back to the garage to check belt and tail and rotor linkages.

[eugenefelisco]

Sometimes the vibration does not come from the tail. Maybe a bend feathering shaft,main shaft or unbalance main blade. If your not too careful picking your heli from the ground you can bend the flybar or move the paddles off a bit to make it unbalance. Another thing is the tail shaft you would not suspect this but sometimes if you land and you scrape or ding the tail blades the shaft bends and you will not notice this untill you roll the shaft to a glass table.

[misterg74]

Then there is slight possibility that the bearings in your motor are shot(LIKE MINE) My heli started getting a random very extreme vibration after about 40 flights with no major crash damage ever. I landed it held the skids throttled up and watched the outrunner on my motor slide up an 1/8 inch and start vibrating very badly........... Just one more thing to check:arggg:

[crfiddy]

still :arggg::confused:

[misterg74]

Sorry to hear that ........... keep lookin.

[blade4oo]

did you chek your block in the head the plastic tends to ware somtimes other than that chek bearings in the head bearings on the main shift its there you just have to find it

[crfiddy]

if i grab the mainshaft collar right ubove the frame it has a little lateral play. should it have any looseness?

[blade4oo]

no you should have no play any play will be amplafied by the dampiners at the blade grips

[Redfire SVT]

My main gear had a cracked hub where the one way bearing is. I had major vibrations.

I would check all bearings on the main shaft.

[crfiddy]

finally got some time to check out mainshaft & bearings. boom and tail comming off if necessary going to lhs to some parts tomorrow. thank you all for the ideas, experiences, & suggestions. ill let you guys know.

[crfiddy]

just test flew, looks like it was the upper mainshaft bearing being bad.
no vibration, can fly idle up. LIFE CAN NOW GO ON! thank you guys for all the suggestions. couldnt have done without your help. thanks again.

Fly hard and be free!