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HelicopterEngines Plugs Mufflers Fuel › O.S. Rear Bearing Issue
06-05-2009 12:59 AM  8 years agoPost 81
Gearhead

rrMaster

Vt

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edited
""When you operated near the limit of the bearing rating, a tiny increase in RPM exponentially affects the bearing capability of holding a load.""

Money Pit,, a "quality" bearing in this size is rated at 30,000, at-least the NSK and SKF are !!, running it at 17, or 18,000 should not hurt them, the NSK in my older OS 50 (silver head) lasted 4 years and I ran a lower gear ratio, the bearing in that engine was still good in that engine when I retired it,,

""Corrosion is still the #1 bearing killer""

yes I agree this is part of the problem, I can add that I let both my Hyper 50s set all winter with "quality" NSK and SKF bearings with no after run oil added and the bearings did not rust,, this tells me the "un-marked" bearings that come in the Hyper 50s (and the ones people buy) are made of low quality metal..

something else I have to add, I have not heard anyone complain about their front NTN bearing rusting..

Jim
Buzz Buzz Buzz

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06-05-2009 01:41 AM  8 years agoPost 82
RappyTappy

rrProfessor

Traveling the USA

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I concur there is nothing wrong with the OS 50 hyper. If in fact
it is a problem due to humidity causing rust, then rather it is a problem with the enviornment it is in. Oh how many Hypers I've had and rear bearings outlast the rings and sleeves. Drive your car in salt and expect rust maybe you guys should move out here to a drier climate.

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06-05-2009 03:00 AM  8 years agoPost 83
Aaron29

rrProfessor

USA

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there is nothing wrong with the OS 50 hyper. If in fact
it is a problem due to humidity
I would concede to that if it weren't for the fact that my other non-Hyper engines' bearings are living longer.

Were my other engines rusting out, I'd be cursing the moist Louisiana air. But they aren't to the extent that the Hyper is. So I curse the Hyper instead.

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06-05-2009 03:12 AM  8 years agoPost 84
RappyTappy

rrProfessor

Traveling the USA

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Lol, exactly. I was just kinda debunking the humid air myth that supposed to be causing rear bearings to go

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06-05-2009 03:18 AM  8 years agoPost 85
Aaron29

rrProfessor

USA

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Ah OK. Your sarcasm was so thick I thought you were serious!

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06-05-2009 05:49 AM  8 years agoPost 86
bradk04

rrNovice

San Diego CA

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My dad and I are trying the head shim theory. So far I think it is definitely smoother and no power loss. The theory goes that it retards the timing slightly which would eliminated detonation which puts stress on the piston, connecting rod, wrist pin and bearing. That's theory, we will see. I think we are up to 2-3 gallons on each engine.

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06-05-2009 01:01 PM  8 years agoPost 87
GMPheli

rrElite Veteran

W. Bridgewater, MA USA

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The hyper for some reason puts more peak pressure on the bearing than other motors. You have all seen the pics, the races have craters in them, the outer race always the same spot, on the power stroke. This is not just a corrosion problem.

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06-05-2009 07:23 PM  8 years agoPost 88
leadlag

rrVeteran

Worthing UK

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I would support what GMPheli says. This is not a corrosion issue unless you are unfortunate in having a Hyper that O.S for a period of time put poor bearings in.

This is a engine balance problem when running at peak power.The races break up at the same point. People are looking at the part the fails assuming it is the part that is at fault.
It is not.

It is the balance of the crank

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06-05-2009 08:06 PM  8 years agoPost 89
fdztec

rrApprentice

Windsor, UK

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IMO it is corrosion that causes the majority of early bearing failures, it seems some people do nothing special and don't get corrosion problems, yet others do. I used to. Try this below, it works for me and a few friends I know who also follow this process. We typically get around 100 flights or more from our hyper 50 bearings now, my latest set of standard steel rc-bearings in my R50 have done 112 flights and are still showing no signs of failure, this same engine destroyed its original bearings in 23 flights and the next set in not many more before I adopted this process.

At the end of each flying session run the engine at a fast idle for a few minutes on straight fuel with 15% synthetic oil and 2% caster oil. Some 4 stoke blends have this mix (don't use pure castor straight as it will gum the engine up if it's not used for a long time). Let it run dry (by disconnecting the fuel supply) and then turn the engine over for 30 seconds on the starter with the throttle wide open to purge the engine of any exhaust gas (note: without the glow power connected, this is not burning it dry). Close the carb completely and turn the engine so it just goes onto compression which closes the exhaust port. This 'seals' the engine to stop moisture getting in.

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HelicopterEngines Plugs Mufflers Fuel › O.S. Rear Bearing Issue
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