Head shake

[Primal]

So I've been chasing down this head shake.

According to the kosmik logs, it starts around 1800 rpm and disappears above 2000. Using a 14t pinion at 80% throttle puts me right in the middle of the shake zone at 1875 rpm. No shakes at 1600 (70% throttle) or above 2100 (90% throttle) .

I've checked blade balance, tracking, and head assembly. Twice. Blades are perfectly balanced and flew fine just a couple of days ago.

I've never noticed it with the yep 120 and a 13t pinion because that setup put me above 2000 rpm.

Any suggestions? Different dampers or the conventional head? Bigger pinion and ignore it?

Thanks guys

[Lighty]

make sure the dampers are lubed, also it took me about 20-30 flights to bed em in.

[Yozim]

+1 on Lightys suggestion. Exactly the same on mine. Lube dampeners and "fly them in" :-)

Yozim


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[Primal]

Ok. I'll rip it apart and redo. Maybe factory was light on grease.

[Rob43]

Once you have the lubricated dampers installed in the head block. Give that spindle a good complete rotation or more to spread the grease inside the dampers. I've found this helps as well. It's easiest with a spindle wrench when the grips aren't installed.

[Primal]

Originally Posted by Rob43

Once you have the lubricated dampers installed in the head block. Give that spindle a good complete rotation or more to spread the grease inside the dampers. I've found this helps as well. It's easiest with a spindle wrench when the grips aren't installed.

Will do. I'm over 30 flights on it now, but if there wasn't sufficient grease on the dampers from the factory could mean that they are drying up and the vibe will get worse.

I'll disassemble it tonight and let you all know.

Thanks

[TBur]

Originally Posted by Primal

Will do. I'm over 30 flights on it now, but if there wasn't sufficient grease on the dampers from the factory could mean that they are drying up and the vibe will get worse.

I'll disassemble it tonight and let you all know.

Thanks

I went with the blue dampers, works well for lower head speeds ( I run 1850 - 2050) and mild 3d. I think i had about 40 flights and numerous regreasing and couldn't get rid of the shakes with the green dampers.

[Scott Bowersox]

For the grease, what are you guys using. I'm using the synergy boto lube for the thrust bearings, would this be good for the dampers as well?

[Magnazan]

I used white lithium. But on next replace I'll go with dry ptfe lube.

[Primal]

Amsoil synthetic grease is what I've used before. Good stuff

[Primal]

Well I took it all apart, dampers were almost dry. Lubed everything up and reassembled.

Still shakes.

I think I'll just abuse it for a while at 2100 and see if it settles down.

[seefest]

Originally Posted by Primal

Well I took it all apart, dampers were almost dry. Lubed everything up and reassembled.

Still shakes.

I think I'll just abuse it for a while at 2100 and see if it settles down.

I have wobble at 1900 HS as well with green dampeners. As somebody suggested, try different dampeners, or just fly above that HS.

[dannylightning]

i dont even lube KBDD dampers. use soap and water to get them to slide on and off.

not sure how lubed dampers would solve anything. i have never had to break in a set of kbdd dampers either. i have never had a 7hv much below 2200 rpm either. so maybe the dampers do need to break in but i doubt it. wobble due to low head speed is usually from dapers being to hard. the kbdd's are not that hard but they do harden up in flight when you start flying hard according to the designer of the dampers. so they should be good for low or high head speed and all types of flying.

[Primal]

Anyone running the blue dampers at 2100 or so headspeed?

[TBur]

Originally Posted by Primal

Well I took it all apart, dampers were almost dry. Lubed everything up and reassembled.

Still shakes.

I think I'll just abuse it for a while at 2100 and see if it settles down.

Though I went blue on the 700, the beat on it plan did work with the green on my A500, took about 40 flights but they settled in.

Show no mercy

[OverTemp]

Any amateur can too.

[Primal]

Well the shake is still there between 1800 and 2000. The problem is I can't get enough headspeed out of the freaking compass motor to get over 2000 rpm. Even with the 15t pinion I only hit 1950 at 80% throttle. Any higher and the governor doesn't have enough headroom and the logs confirm this.

How low is the actual KV of this motor? I knew it was lower than advertised but this is ridiculous.

[Stevewashere]

Originally Posted by Primal

Well the shake is still there between 1800 and 2000. The problem is I can't get enough headspeed out of the freaking compass motor to get over 2000 rpm. Even with the 15t pinion I only hit 1950 at 80% throttle. Any higher and the governor doesn't have enough headroom and the logs confirm this.

How low is the actual KV of this motor? I knew it was lower than advertised but this is ridiculous.

Ive heard its as low as 460kv

[Primal]

That's what makes math says, are 460 or 470. How the heck do I get my headspeed higher?

Does anyone make a 16t mod1 helical pinion?

I'd rather not replace the motor, but for now it looks like my only option...

[Ah Clem]

Danny,

"not sure how lubed dampers would solve anything."

The spindle move inside of the dampers, and the dampers move inside of the head pocket. The don't move a long distance, but they do it very rapidly.

If they stick, they wear out faster (bear in mind, that at 2200 RPM, the spindle is flapping one full cycle, 2200 times per minute).

Lubing them is an old trick to make the last longer and eliminate one source of vibration.

Mine have lasted a lot longer with lubrication.

Soap helps you get them installed, but does not provide long lasting lubrication.