Tail vibration (something else to check)

[JeffKollin]

Well after having the problems I have been having I have found the reason for my tail vibration that I thought you guys might want to look into. My tail fin was vibrating like crazy and my fuel was foaming. I have found that the start shaft was bottoming out on the top of the crankshaft. I took the starter coupler off to see if there was any free play (up and down) and I had none. After taking the motor out and removing the start shaft, I put the start shaft down through the clutch and there was a pretty good gap between the c-clip and the clutch/oneway. Looking at the bottom of the start shaft you could see that it had been rubbing on the crankshaft. I have built this per instructions and used the washer between the clutch bell and c-clip. I left the washer in because I would rather have the bearing on the washer than the clip so I took a little off the start shaft so there would be some freeplay with the coupler off and then installed the coupler so there was no movement in the start shaft and reinstalled the motor. Hovered in the front yard and the tail fin is smooth and tail is alot better. Just thought I would pass along some info maybe to help somebody else out that may have a problem with vibration. I am using the Redline 53 engine and also have the washer below the fan as I do with my other SE's. This was found on my torque tube version X50

[Elgyn]

I don't think my OS 50 is rubbing but I'll check it this week if I have time. OS have a washer that goes between the crank and the hub as a spacer YS doesn't need one(so I've been told). Does the Redline have one as well?

[JeffKollin]

Yes the Redline has one as well. The washer between the front bearing and the fan hub is only to shim the assembly up so that the clutch aligned properly in the clutch bell from what I can tell. I took the washer out and all that did was lower the clutch/fan. I do not know if this is a problem with all. It is just what I found after dealing with a unsettled tail since the heli was assembled.

[johnbs8]

jeff, im curious as to what the original length was before you shaved it and how much you took off. just curious if it was a quality controll miss at the factory...

[JeffKollin]

I did not measure it because I did not have another to compare it to. As far as how much I removed , it was only about 1/16 to an 1/8 of an inch. Just enough so that it was not resting on the crank and to have a little freeplay when assembled with start coupler off.

[KouDy]

Can you post photos or mention pages from manual? I think i know which washer you mean but want to be sure... I will take photos later, i have heli apart now...

Edit : Is it shim 2 on page 16?

[JeffKollin]

Item #2 is the clutch shim between the clutch and fan, that needs to be there so the clutch fingers can work freely without getting hung up on the fan when bolted together. If you have your heli apart, with your motor assembled with the fan/clutch bolted to it take your starter shaft out of the starter bearing block and put it into your clutch oneway. Leave the snap ring on the start shaft and see if the snap ring rests on the clutch. The best way would to be leave everything in the heli and take the start coupler off the start shaft and see if the start shaft has any movement up and down. If it does not then I would have to say that it too is resting on the crank on the engine. If it does move up and down a little you would be ok. But after that you would have to take the engine out to hold the start shaft up to put the coupler back on so it does not move up and down. I was refering to the washer between the engine block and the fan. Some say some engines need it and other engines dont. I have always used mine because I run the Redline 53 in my Raptors.

[KouDy]

I see, this washer. All i know is that i have it there. My Helikraft order is still on the way (it will take off from Taipei to KL in 2 hours and 10 minutes ) so won't be testing anything now. But i think the metal fan upgrade i have ordered (KL0049). There is note :

The fan does not require the use of the clutch spacer as the clutch mounting area is raised.

Do not install the washer supplied with the engine between the fan and the front bearing, the fan is designed to be mounted flush to the front bearing directly.

So i think i will be removing washer on the engine block and will have to figure the clutch spacer thing...

[JeffKollin]

I see where they have already included the needed space for the clutch.

[johnbs8]

jeff, say what??

[JeffKollin]

Oh, sorry. I was refering to the metal fan that Koudy was getting.

[JeffKollin]

Went to a funfly today and the tail was great. On another note, a local flier showed up with a new Titan SE never been flown. I went through his heli with him to make sure everything was set up right and when I went to start it I noticed the start shaft was tight when spinning the motor over. After tearing it apart to find out why the first problem I found was he was running the washer between the crankcase and fan which was causing the clutch to sit tight up against the clutch bell. Removed the washer and reinstalled his motor and still the start shaft was turning the engine in both directions when turned.Took the motor back out and removed the start shaft and his also was too long. So now it has been determined that it is not a problem with the crank being too long in the Redline 53 because he was using a OS hyper 50. So with there being an issue between to different engines I would have to beleive that it is an issue with the start shaft. So I came home and ,hecked both of my SE's and both of them are also tight to the point that the start shaft does not turn freely in the opposite direction of the oneway.

[johnbs8]

Wow that's interesting. I wonder if that was the cause of my tail wag on the se i used to have.