Nasty tinny sound from 600N at idle - Still can't find the problem?

[loiphin]

Hi All,

I have had my 600N Pro for about 3 months now. After the first month I started hearing a tinny type of rattling sound, which seems to be coming from the clutch bell while the heli is idling. I ended up replacing the entire clutch assembly but it was still causing the sound.

When the heli idles, the clutch bell seems to resonate with its pinion against the main gear. (well thats what I think it is). I thought it was happening because of worn bearings in the clutch assembly. So I changed the bearings and it improved a bit but after a while it was back again.

I had read about using the thicker HD raptor lining, so I bought another clutch assembly and replaced the whole lot again (bearings, started shaft, bell with HD liner, and clutch).

Now with the newer HD liner, the clutch drags a bit... but I still hear this stupid sound. Could my engine have a bent output shaft? Not that I ever crashed it, so it should be true. Or should I replace the entire frame to get better tolerances between the engine, clutch assembly and the main gear??

I then decided to check the main shaft bearings.... although I guess there it wouldnt cause my problem, as this only happens when the heli idles, and of course the main gear is stationary. (Once the heli has spooled up, there is no noise). I found that the middle bearing was a bit rough and vibrated when I spun it with my fingers. I have replaced it, and now am waiting for the weekend to try again.

This clutch sound thing is driving me mad. I really love my 600N, and I can't fault it, besides the clutch. But this problem may stop me from buying another 600N in future. I have heard some people just ignore the sound, but I would love a heli that idles nice and quiet.

Has anyone managed to sort this out?


Please help!


Thanks,


Loiphin.

[Philng]

Its probably the bearings in your engine, It makes a rattling noise at idle and goes away when the RPM is higher. I've heard the OS uses the wrong kind of bearings for that kind of application and they wear out extremely fast.

[loiphin]

The reason I dont think its the engine bearings is because it is intermittent. Some times the engine dies when it happens because I think the clutch bell vibrates and causes it to bite into the clutch.

I have also had the engine out and turned it over to feel if the bearings are bad. It was smooth as glass.

[Philng]

I don't know then, you try changing the bearings for the starter shaft?

[Danish Heliflyer]

It could also be the piston ring. That can only be hearing at idle. If one of the ports in the cylinder has a litle nut, the ring will run into it and give a tic tic sound in different frec. If the bearings was done, you whont be in doupt, it will only get worse..

[aevans692]

I know the sound you mean as I get it too... and as soon as you spool up its gone...

I have learnt to live with it as I have checked every thing bout three times, it sounds like the clutch rattling inside the bell housing.

[bigempty12]

the guys at align gave me a building tip. they told me to take a small file and open up the alignment holes for the main shaft bearing blocks and the bearing blocks for the clutch bell and start shaft. If you think about it, when you are putting the frame halves together and trying to align them, if the holes don't have a little bit of movement, you won't be able to align the frames correctly. I did that and moved them around until I could get the main shaft without the rotor head to drop through all 3 bearing effortlessly. Then focused on the the motor and clutch bell alignment. If you have ever built an older MA, you know exactly what I mean about aligning the two. I started out by loosening all of the motor mount to frame screws and then bolting the engine in without the fan shroud on. At that point you can start to move the motor and the bearing block around a little to make sure the clutch does not touch the clutch bell at all. It takes a little time and a very fine touch, but it can be done. Once you think you have it, tighten everything down, and you're good to go. Spending about 2 1/2 hours aligning my frame and motor really paid off, as I have no issues at all with the heli or motor. The reason I say all of this is because it seems to be an issue that plagues these machines, and it's one that one person can have, and the other will be just fine. A friend of mine built a 600 pro and he had the same issue you are having as well as many other people. We finally narrowed it down to the start shaft and clutch and clutch bell assembly. We tore his down, and he had alot of drag on the mainshaft, which tells you that the frame rails are not aligned. We opened them up, aligned the mainframe properly as well as the motor, and problem solved. Just what I found though, hope it helps.

[loiphin]

Thanks for the tip! When I recently checked the main shaft bearings, I ensured that they were nicely aligned when I dropped the main shaft back. So the main shaft slides in and out of the bearings nicely. Perhaps the main gear has worn a bit and now there is a bit more play between the main gear and the pinion, which allows a bit more play, and thus the vibrating clutch bell? I may change the main gear, just for the hell of it.

Also despite having very limited clearance with the new thicker Raptor 90 clutch liner, the clutch bell still spins freely when I spin it by hand.

loiphin.

[OHIOBOWHUNTER]

Is it possible something is loose inside your pipe , like a baffle ?:dontknow

[loiphin]

No, because the noise is intermittent and only happens during idle. Whilst flying and the clutch is fully engaged, its fine. But thanks for the thought.

[Chief heli]

Are you sure its not the fan hitting the fan-shroud?

Look at these 2 movies (my 600N):

Before:
http://media.putfile.com/Engine-noise-2-91

Here is after fully raising the fan-shroud:
http://media.putfile.com/Fan-shroud-noise

Still not enough, but I can lower the engine a bit, so I did!
Have to test, think I'll do tomorrow!
I loosened up the shroud when idling. When I pushed the shroud down the noise increased. So it must be it!

Hope this helps you out!

Greetz,
Chief ;)

[Mike Fortin]

When I built my 2nd 600N I used the metal Align fan, I too got a tinny metallic sound upon spool up. After some adjustments to the motor and fan shroud it went away.

Mine would go away in flight and it wasn't an issue, I just never like hearing it upon startup.

[loiphin]

Thanks for the input guys, but it doesn't sound like what your video's are showing. Fast forward to the last 10 seconds of this video and listen carefully. It is a sound similar to a vibrating canopy, but I am quite sure its the clutch bell... (have had the canopy off and still the same sound).


http://www.youtube.com/watch?v=YF4NWjbRgOc

[aevans692]

I will check mine in the morning , I know that my frame is all lined up fine..

[reiserrob]

its probably the engine bearing, OS hypers are notorious for throwing rear bearings. I know, I've had a few go myself and the only time it sounded bad was when I was idling, once I would throttle up it would go away. I would disassemble the engine and remove the crank and move the inner race of the larger rear bearing with your finger, if you feel any notchiness or roughness, the bearing is on the way out. Replace and OS told me to use after-run oil to keep the leftover fuel from absorbing moisture and causing the inner bearings to corrode.

[loiphin]

I did have the engine out and I carefully turned it over to feel the bearings. They felt very smooth, but then again I didn't have the bearings out.

The sound I get is intermittent. And it does sound like it comes from the clutch bell. I should get a wooden rod and prod the clutch bell when it idles to see if it makes a difference to the sound.

loiphin.

[Mike Fortin]

I watched the video and didn't hear the sound.

Are you running a metal fan?

[loiphin]

Yes, I am running a metal fun. I will do a quick video this evening when I get home from work to give you a better idea of what I mean.

Cheers,

loiphin.

[loiphin]

Here is a proper video showing you the problem I am experiencing with my Trex 600.

Please let me know what you think!

http://www.youtube.com/watch?v=GC6oVBWP6pw


Thanks,


loiphin.

[DebianDog]

Yikes!!! It sound like the piston hitting/grinding to me.

[rototiller]

OMG ! That is like nails on a chalk board !!

You can hear the motor drop rpm when the fan hits what ever its hitting. Its definitly hitting somthing but what ?

I would pull the motor, get the shroud off and put the motor back in to see what it does. Look inside the shround, maybe a too long screw somwhere? I dont think its in the motor, it just wouldnt run that good if it was. Pull the pipe and shake it to see if anythig is rolling around it.

DK

[loiphin]

I am certain its the clutch bell, but I just don't know how to fix it? I have pulled the engine a number of times to check the fan etc.. and I am sure the fan is not at fault.

But thanks for the suggestion anyway.

loiphin.

[rototiller]

So the fan is tight and shows no sign of rubbing? Then the clutch could be lose. Did you check the pipe? If its none of those it has to be in the case of the motor but, theres not much room in there for somthing to sit with out getting hit. Unless your bearings are blown out. Then It might show up as an intermedite problem like that.

Man that sounds nasty. might have to go back to basics. Pull the clutch housing and bulk head. Leave just the motor and fan/clutch in the bird and start it to see if its the motor side or the clutch bell side?

DK

[loiphin]

Yip, pipe is good. The fan is nice and tight. No rubbing what so ever. Yes, I do think the clutch is slightly loose, even though the bearings are goo. Thats what I think causes the noise. The clutch bell vibrates as the shoes rubs against it. Must be a design fault or something.

loiphin.

[invertmast]

Yip, pipe is good. The fan is nice and tight. No rubbing what so ever. Yes, I do think the clutch is slightly loose, even though the bearings are goo. Thats what I think causes the noise. The clutch bell vibrates as the shoes rubs against it. Must be a design fault or something.

loiphin.

ya sure the nut that holds one of the bearings on the pinion hasn't come loose causing it to move more than usual