main gear wobbles up and down

[bthuss]

all, i have been re-building my 6hv this past week and i finally got to do a bench test today and when i spool it up (no tail blades), i see that the main gear is warped a bit and moves up and down and seems to make some odd noise.

as i it gets faster, it seems to dampen out, but then at speeds above about 50% throttle, it gets a loud harmonic type noise up near the motor. not sure if its the main gear doing it, or something else.

anyone have ideas on whether i can flatten it out somehow?

also, my main mesh might be a tad loose, but would that contribute?

my tail belt is on the loose side because when i had it tighter, the black tail belt gear would wobble a bit too. loosening it up made that fairly flat.

when i put on the tail blades (KBDD extreme 96), it was ok at slow speeds, but then it started to vibrate at speeds over about 40% throttle and the harmonic was so bad it was bouncing up and down at the tail.

thoughts on tighting the tail belt and the mesh to help this? or does it sound like something more sinister like a bearing?

note that all of the parts are new with respect to main gear, bearings, etc.

thanks

brad

[Cullen Colapietro]

A few things to check

Be sure that when you disassemble your main gear/hub dealy, that the main gear itself is flat. If it is, be sure that you are assembling this main gear auto rotation hub properly, make sure the hub is seated in the main gear. I had a 450 main gear where I didn't pay attention and the main gear was really badly warped. I took it apart and put it back together and all was good again.

Another thing to be sure of, is to not over tighten the jesus bolt in the hub. It should just be snug, the nylock nut will hold it in place.

[bthuss]

i might have to do that. i loosened the jesus bolt (although i didn't think it was very tight) and just tightened it ever so slightly and it seems a LOT better.

i still have some odd pulsing type sounds at higher RPMs but it almost seems like its coming from the motor side. i am running 15 degree timing now and i cant remember if i was running 18.75 last time.

what are you all running for timing?

thanks for the help

[Cullen Colapietro]

18.75

Mke sure your Gov. Is off if that is what you desire. Governors can cause a motor to pulse.

[bthuss]

i'll re-calibrate the ESC and double check that the gov setting is off...im pretty sure i made sure it was set to the default off position but ill check anyhow.

also i wonder if it has anything to do with the throttle calibration. my TX has the throttle channel set to 0 subtrim and 100%,100%, but during v-bar setup i see that the throttle channel is way off center (0) and max/min values are no where near 100.

if i updated my TX to show some subtrim and adjusted the ranges so that the vbar was at 0 midstick and -100/+100 at the ends, the throttle channel was not responding properly when i booted up the heli. (i.e....it took almost 1/3 stick just to get the motor running).

what is the recommended procedure for setting throttle?

for what its worth, right now i left the TX at 0 subtrim, 100%/100% and then just calibrated max and min stick to the ESC using the ESC config procedure. the vbar still shows the numbers for throttle as way off center and endpoints, but it *seems* to be ok

thanks

brad

[TheBum]

What mode did you select in the Receiver setup tab? If you selected the regular "Spektrum satellites (1 or 2)" option, try to make your throttle channel subtrim and ATV roughly match the subtrim and ATV for the other channels you changed in the Transmitter setup tab, at least in absolute magnitude. I had to do that to even get my ESC to arm.

A better idea is to select the "Spektrum satellites digital center (1 or 2)" option. It will bring the subtrims and ATVs much closer to 0 and +/-100, respectively, when you do the transmitter calibration.

When I set up the VBar governor, I set the VBar throttle limits to +/-100, set the throttle limits in the ESC, and then adjusted the low throttle limit in the VBar per the instructions. I didn't even touch the upper throttle limit in the VBar.

[bthuss]

i pulled out my main gear and the motor and took apart the main gear and things look pretty flat to me.

one thing on the motor i see is that the pinion seems lower than it should be where the top edge of the main gear is almost in-line with the top edge of the pinion.

is this ok, or should i slide the pinion up some?

there is only about 0.5mm between the shaft snap ring and the bottom of the pinion.

[Cullen Colapietro]

That is how my pinion sits, flush w/ the top of the main gear.

[bthuss]

well i decided to disassemble the motor again and pull the pinion and check things out. everything seems ok and the bearings seem to be in place and moving smoothly. i reset the pinion a hair higher and ill try it out tomorrow once the locktite sets.

i am going to try 18.75 and 12 degree timing as well and see if it makes any difference.

thanks for the help