rrTV-PHOTO   New HD TV
HOME   rrTV-PHOTO   GALLERIES   MY GALLERY   HELP-FAQ
myHOME PM pmRR MEMBERS 563 ONLINE 20 EVENTS SEARCH REGISTER  START HERE
 
2 pages [ <<    <    ( 1 )     2     NEXT    >> ]561 viewsPOST REPLY
Autography FlightPower . Advantage Hobby . Revolution Models

.
.
Gasser Model RC Helicopters > Clutch bearing on Predator Gasser 26cc
 
 
Gas and Go
Heliman
Location: Western Wisconsin- USA

How long have you guys had you clutch bearing last, I am talking about the predator gasser series, and the 29 mm od, 19 mm id and 5mm thick bearing that goes between the pinion gear and the clutch bell. I have had to replace mine twice now, each one after about 37 flghts ( I could hear it making grinding noise at idle, and when I would spin main gear by hand.)
I have clutch dialed in to .001" and gear mesh to main gear was also checked, and set per manual.
I dont think I should have to replace bearing this often; is there something else I sould check for alignment.
07-22-2008 02:20 AM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

The only time had to replace it is after a huge crash. It's strange yours would wear out that fast. I can't think of any reason why it would, are you buying good bearings? You might want to try a high quality bearing from Boca or something instead of the ones that Century sells.


Nick Crego
Still wanted by the government, I survive as a soldier of fortune.
07-22-2008 03:21 AM
 
 
Billme
Key Veteran
Location: MS

Have you done the oring mod for the auto hub?
Its a cure for any problems in the drive train..Its possible your bearing may have to tight a fit in the first place..Cheap bearings run good believe it or not when done right, hehe

Bill
07-22-2008 04:59 AM
 
 
Gas and Go
Heliman
Location: Western Wisconsin- USA

No I have not, dont know what that is.
07-22-2008 05:01 AM
 
 
Billme
Key Veteran
Location: MS

Read, and study this thread...
http://runryder.com/helicopter/t426711p1/
also, http://www.helifreak.com/showthread.php?t=81932

Bill
07-22-2008 05:06 AM
 
 
Gas and Go
Heliman
Location: Western Wisconsin- USA

i have read thru it, and will have to tear apart, then the picture will probally make more sence. Is there any measurments of what these o-rings take up. Because I have teflon at work and would be able to machine up some spacers if I could get the dimensions from you.
07-22-2008 05:54 AM
 
 
Billme
Key Veteran
Location: MS

The dia 14mm ID by 1mm...You can use any type spacer on the top, but its still good to use a oring touching the clutch itself...this will allow the small tilt the clutch needs to align itself under load..if you use a flat spacer, it works against the tilting action, which i don't think at this point is good..
Once you get into it and see, you'll see what needs to be done.. the objective is to sandwich the clutch in position, and off the floor of the oillite bearing...
You can use flat shims on the bottom to take up play under the oring also... You should end up with the sleeve just protruding out about1.5 to 2ths clearance..
I use the 4 orings on top to keep it simple for those who don't know fitting or machining techniques...
Century is going to do their own fix in the future... This works very well, and will make the machine much better..
Bill
07-22-2008 06:29 AM
 
 
Gas and Go
Heliman
Location: Western Wisconsin- USA

I will probally make a flat spacer then just file the edges rounded, one more question. When you say you should end up with the sleeve just protruding out about1.5 to 2ths clearance.. Could you express this as a decimal format.
07-22-2008 06:45 AM
 
 
Billme
Key Veteran
Location: MS

.0015 to .0020

This is a on going test here with the clearence...it seems the tighter the clearance, the better so far..
07-22-2008 06:52 AM
 
 
ppridday
Veteran
Location: Canadian in Detroit Lakes MN / Guarapari Brazil

If the clearance is a little on the tight side to start with will the teflon O-Ring not 'bed in' a bit to give a perfect clearance in a short time or is it not good to go too tight to start with?

Paul

"There's someone in my head, but it's not me..."
07-22-2008 07:01 AM
 
 
Billme
Key Veteran
Location: MS

The orings are pretty tuff, I'm sure they might wear..right now, its to early to tell...I have seen a lot more clearance and still work good, but I still say keep it minimum...if you can feel it, but its hard to see, you are close enough...

I'm also just cleaning the hub with contact spray cleaner, and not lubing the clutch.. I do put a lite touch of grease on the top orings for auto purposes, but don't get it on the clutch..
If the heli doesn't want to settle down, just run it, and then clean the hub till it does.
I have one right now that is is smoothing out after each flight..It may take several fights, but you will notice a difference right off the bat.
Bill
07-22-2008 07:22 AM
 
 
Gas and Go
Heliman
Location: Western Wisconsin- USA

are the orings supposed to be in direct contact with the teeth of the sprque clutch, and sandwitch them tight, or should there be some clearence for them to move.
07-22-2008 06:52 PM
 
 
AceBird
Elite Veteran
Location: Utica, NY USA

Quote 
How long have you guys had you clutch bearing last, I am talking about the predator gasser series, and the 29 mm od, 19 mm id and 5mm thick bearing that goes between the pinion gear and the clutch bell.

I am a little perplexed here, I think he is talking about a different bearing then the auto clutch.

Gas and go is it possible you are destroying the bearing when you replace it because of your technique? I would have to say never for replacement time. That bearing is so over designed for that application when assembled correctly. However, because it is so large it is absolutely imperative that the bearing is pressed in with out being cocked. It must run bang on to the axis of rotation or it will eat itself up in 37 flights or so. It is also possible that the machined surfaces of the bell and bearing housing are improper or have been damaged.

Ace
What could be more fun?
07-22-2008 09:23 PM
 
 
Gas and Go
Heliman
Location: Western Wisconsin- USA

I am talking about the bearing that holds the clutch bell.

It is not possible that I have wrecked the bearing when replacing it because I have not done so my self, after it went out the 1st time I purchased the clutch bell assembly from century and installed.

On the pruchased assembly from century (the second clutch bearing) went bad because there was not enough of a press fit between the inner race of the bearing and the boss of the clutch bell that eventually gave out, developed slop, allowed the inner race to spin against the aluminum and eat away at it.
I just love cheep chinese crap, highly doubt I will buy another heil from this company; I am really tired of having to modify and reverse manufacture things.
07-23-2008 02:47 AM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

FYI, that bearing is a common size for bicycle wheels. When I replaced mine, I ended up getting one from a bike shop for $8. Worked great.
Quote 

I just love cheep chinese crap, highly doubt I will buy another heil from this company; I am really tired of having to modify and reverse manufacture things.

Agreed. There are some things on the Predator that are ridiculous, a great example is the O-ring mod that Billme posted. Why don't they just make it right? They've continued to manufacture it with known flaws for years now. It is a great heli, I loved mine, but you'd think that Century would actually fix problems on a heli that costs anywhere from $1000-$2100.


Nick Crego
Still wanted by the government, I survive as a soldier of fortune.
07-23-2008 02:53 AM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

OK - right thread for this post..

If I remember the notes from Bill he stated that he believes the Spraq clutch issue affects most all one-way's of this style including the MA's. If course I don't have experience (yet) with the Spectra but might be interesting to see if supporting the one-way bearing could help the MA heli's.

Just about 5 gallons through my P-gasser - no maintenance issues so far. Just fuel and fly. I do have some build issues with the kit and if I were to purchase a new kit today I might buy the MA but I'm happy with my Pred.

build issue I had:

- Yep, the main gear needs more attention from the engineering dept. The main gear should NOT be that close to the bottom of the main gear for one. I think they did not take into account the changes in the NX clutch/main gear assemblies and how they would affect the frame sets. To me it looks as though the frame dimensions could be adjusted so that the main gear assembly is in the middle of the opening rather than at the bottom. Also perhaps setup a good mechanism for preloading the mainshaft thrust bearings - I do like the idea of having them.
- Gas tank plumbing instructions left me with a tank that sprays incoming fuel across the vent tap when fueling. Sprays fuel out of the vent line during gas-up unless I tilt the heli up on it's nose.
- Also the tail servo front mount relocation kit does NOT fit the NX tail transmission. This was not addressed by Century even though I brought it up to them and they acknowledged the issue. For the money, the carbon frame kit should come with the front mount tail servo hardware IMO.

...yep...
07-23-2008 03:35 AM
 
 
Eury
rrProfessor
Location: Ankeny, IA, USA.

I dunno, I've never had a problem (or heard of one) with an MA one way, or a Predator one for that matter. the biggest benefit I see on the O ring mod is that it lifts the main gear up off the frames.


Nick Crego
Still wanted by the government, I survive as a soldier of fortune.
07-23-2008 03:40 AM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

I do know that the main assembly was kind of jammed a bit sideways against the pinion and the assembly could move up/down a bit. This along with the bottom of the main gear grinding on the frame is what prompted me to ask for help here. Once Bill let me know about the Oring and CA fix I took it apart and noted there was wear on one side of the mainshaft and not on the other. Since I applied the CA fix to the inner sleeve and put the O-rings in the main one-way it's been smooth and trouble free. I think this fix has more to do with stabilizing the bearing assembly than raising the main gear. My main gear is still way too close to the lower frame but since the assembly can't rock like it did it hasn't been an issue. My thought with the clearance issue is the frame dimensions need to be adjusted.

...yep...
07-23-2008 03:56 AM
 
 
Gas and Go
Heliman
Location: Western Wisconsin- USA

jschenck: Yea I had problems with the main gear also, had it together and apart 4 times trying to fix that during the inital build. Called the company, and got the answer, "you must have someting wrong."

Century needs to raise up the main gear, they just convently pretend its not a problem, to fix mine i chucked it up in a lathe and turned down the thickness, had to take off approx .020", now it clears lower part of frame well.

as for the other fixes I had problems with the torque tube supports comming loose and moving around on me. So I drilled and tapped a hole in them and bolted them tight thru the tail boom--- have yet to see how well this works.

I have been thinking I should design up my on heli and market it-- AMERICAN MADE!
07-23-2008 04:27 AM
 
 
jschenck
Elite Veteran
Location: La Vista, NE.

I know other have had problems with the TT support bearings spinning - I read somewhere here a suggestion to drop some oil in the bearings and run them until they are loose. It felt like there was a high viscosity grease in the bearings which put drag on them. I oiled them with some machinist oil and worked them until they spun easily. No issues since my initial build.

As far as Century's support - they were always willing to send me parts to correct kit problems, very friendly but I was always told more than once they didn't have anyone on staff that knows the Predator. (??!, did I call the right place?). I have not had to contact support since finishing my build so perhaps they have brought in someone who can field support calls on the Preddy now but at the time that was an eye opener. Fortunately for me I have not needed support or spares since finishing my build.

Oh, another issue I currently have. IMO the stock 6.28 (88/14) gear ratio is too steep. I think the 90/13T gears would suite this heli better. That'd be 1800 RPM with the suggested 12500 RPM on the engine which would be great for sport flying and for those of use who like a higher headspeed maybe the 90/14 pinion (6.42), or 88/13 (6.76) main gear would step it up. 6.28 just seems to bog too easily for my heavy handed flying. I think I'll move to the 13T pinion when I tear into it this winter.

...yep...
07-23-2008 04:47 AM
 
 
2 pages [ <<    <    ( 1 )     2     NEXT    >> ]561 viewsPOST REPLY
CarbonXtreme . Midland Helicopters . HeliProz

.
.
Gasser Model RC Helicopters > Clutch bearing on Predator Gasser 26cc
 PRINT TOPIC Advertisers 

Subscribe to This Topic

Saturday, November 22 - 2:27 pm - Copyright © 2000 - 2008 runryder.com | email | link to rr | runryder needs cookie