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HomeAircraftHelicopterCentury Radikal G20-30 N640 Hawk Predator › Eccentric Radikal Main gear
01-18-2010 08:17 PM  8 years agoPost 1
mrloudly

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Naseby Northampton England

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Noticed about 1/32" eccentricity in the main drive gear. Pulled it to check and sure enough the bore of the gear does not sit concentric with the auto hub. There's nothing I can do to resolve apart from replace. Not sure if it's the gear or hub. Will change out both.
Anyone else notice this?

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01-18-2010 08:50 PM  8 years agoPost 2
rccarguy

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Boston MA

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Had no issues with runout on either the original 84 tooth main gear or the 90 tooth that replaced it (now running 6.9 gearing). Only thing I did notice was on the original gear, the material is split slightly inward and outward from the countersunk holes that secure the gear to the hub. If you look at the gear, the edge of the countersink is right at the edge of the material on the auto-hub side and not much further away from each of the lightening holes. Not sure if this could become an issue or not over time, but didn't give me the warm and fuzzies when I saw it, hopefully the 90 tooth is a bit more robust.

You can clearly see the splits as black lines on the side of the screw holes in the picture...

XCell Spectra G
Radikal G20
Some obsolete nitro helis too...

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01-18-2010 08:57 PM  8 years agoPost 3
mrloudly

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Naseby Northampton England

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loock carefully at the countersink diameters. From the pick I'd say they're not centered. Look how the rhs holes countersinks in the pick encroaches on the bore but the left side doesn't.
Looked again maybe it's the pic angle...
I'll clock mine up on the inner gear face and let you know.
Makes you wonder why they didn't offset the screw holes to the lightning holes?

Andy

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01-18-2010 09:47 PM  8 years agoPost 4
rccarguy

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Boston MA

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No, you are correct, the countersink holes are NOT perfectly concentric to the hole for the hub, didn't notice that before, but the gear appeared to run true installed! Not sure which is off, the center hole or the screw holes, but one or both definitely is

If I had time I'd go out in the garage and chuck it up in the lathe and take some measurements, but as I'm leaving on a business trip in the morning, it will have to wait for another day.

Yes, offsetting the lightnening holes would have made more sense, there's not much meat surrounding a good bit of the screw holes as-is

Edit - take a look at how the lightening holes encroach on the bevel on the outer ring, they're not concentric either

XCell Spectra G
Radikal G20
Some obsolete nitro helis too...

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01-19-2010 02:32 AM  8 years agoPost 5
nowinkk

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LandBelowTheWings

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I noticed eccentricity in my Redikal G20 main gear too. I opened the hub, aligned the hole and retightened the countersunk screws but to no avail.

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01-19-2010 05:11 AM  8 years agoPost 6
mrloudly

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Naseby Northampton England

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"Edit - take a look at how the lightening holes encroach on the bevel on the outer ring, they're not concentric either"

Looks about 1/32" to me

The screw holes are clearance anyhow, the gear location comes from the
countersinks which are out.

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01-19-2010 06:03 AM  8 years agoPost 7
Felino

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Mexico city

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+1 Here

I also have the same problem. Wating on 90T main gear and one way sleeve. I think the problem is in the sleeve, makes the whole main gear assembly eccentric.

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01-20-2010 04:40 AM  8 years agoPost 8
rccarguy

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Boston MA

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I don't think the problem is in the sleeve, but not much of anything would surprise me at this point, the manufacturing quality I'm seeing on my Radikal is a bit variable.

Fortunately the 90 tooth main gear appears to be running true, and it's a good thing as you need a feeler gauge to measure the clearance between it and the tail belt, you'll see what I mean when you install it...

XCell Spectra G
Radikal G20
Some obsolete nitro helis too...

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