Fan hub overly tight on engine shaft?

[spdntckt]

Anyone else notice that the fan hub is SUPER TIGHT on this bird? compared to other hubs - like the HyperHub on the synergy - this thing cant even press on - i had to use the engine nut to tighten it all the way down.. this begs the question.. how the heck are we going to get it off?

anyone had to remove it yet?
Btw - this is on my new OS91hz as well as my friend's YS91SR...

[tcast305]

Same on three builds I did. One on OS 91SZ and two on the Align 91HP, all of the were tight fit, and you have to use the nut to drive the fan hub down. If or when you have to remove the fan hub and you can't get it off by hand, then you could use a puller.

Thanks.

[sonofcar]

yep there tight! everybody is like that i think. (bobs was in his vid). going to maybe make a puller for take off. (like ma'smaybe) better tight then loose.

[HeliSmith]

Yup had the same issue with my OS .50 on my 600NSP build. Then on the 700N I didn't even trip I just put the nut on and tightened it down.

[spdntckt]

Yeah i did the same thing to get it on (cranked down on the nut), i am not so concerned about getting it on - more about getting it off.. for the eventual need to replace rear bearings/etc.. since the fan bolts on from the bottom getting a puller in there over the fan hub is going to be interesting.. if the fan bolted/removed from the top it would be easier to get a puller in there...

[HELINHAWAII]

Mine was really tight too. I did have to remove it as I forgot the shim that goes between the motor bearing and the fan hub. You do have to remove the fan with a short allen tool but getting the fan out of the way enought to attach a gear puller is no problem at all. And with the gear puller, it came off in 5 seconds.

A gear puller is really a pretty good tool to have around for more thn just model work. You'll use it more than you think. And they can be cheap (http://www.amazon.com/s/ref=nb_ss_gw/002-9254458-0238440?url=search-alias%3Daps&field-keywords=gear+puller) too!

[DesertFlyer]

My hub, engine fan mount, would not go over my YS 91 shaft. I used a drill bit, can't remember size, and by hand opened it up so It would slide on the shaft. Works fine now. Had I forced it on, I would have never got it off.

[Danal Estes]

We've built a bunch of them at Andy's shop. The YS seems a hair tighter than the OS.

We've gotten most of them off with the "two screwdriver from below" method, CAREFULLY. Had a couple that were tight enough to need a puller. I happen to have a puller that has a "cage" around the legs... this thing is perfect. Sears (and maybe others) sell them. Kinda expensive at S, but worth it. They work GREAT, easy and no damage.

BTW, I pulled mine because I was chasing a vibration. I 180 it (no joy). Then I bought a dial indicator. The hub itself is good to less than one mark on a .001 dial. The clutch, on the other hand... Yikes! had one that was 6 out, and another that was about 1 full mark. Needless to say, the 1 mark clutch is now on the bird. We'll find out how good that is as soon as Gustav passes (tomorrow, I think).

[spdntckt]

thanks for the messages on this. i have a battery terminal puller which i find is about the right size for most heli needs.. just was not sure it would fit over the fan. i'll give it a try. interesting to hear that everyone else is experiencing the same problems... the HyperHubs on Synergy fit perfect and can be removed by hand. on mine i got less than .002 all the way out on the start shaft (about 4inches from the base of the motor).i never measured it at teh base but it will certainly be less than .001

cheers!

[Danal Estes]

Remove 4 screws, drop the fan around the shaft, and use the puller on the "ledge" on the hub left behind by the fan.

[HELINHAWAII]

Remove 4 screws, drop the fan around the shaft, and use the puller on the "ledge" on the hub left behind by the fan.

Like I said...EASY!

[Kinger]

Just a quick note for anyone else having problems getting the hub off. DEFINITELY get yourself a cheap gear puller from Harbor Freight or some other tool supplier. I picked up a $15 set of 3 pullers and with the smallest one it made this job a 5 minute process. It was more of a pain removing the fan from the hub than it was removing the hub from the engine crankshaft :)

Thanks again HELINHAWAII for suggesting this tool.

[HELINHAWAII]

No sweat Kinger... glad I could help!