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Why do OS engines go through rear bearings so much?

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Why do OS engines go through rear bearings so much?

Old 09-24-2020, 10:00 AM
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jester_s1
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Default Why do OS engines go through rear bearings so much?

Specifically, the 65 AX seems to have quite the reputation for eating its rear bearing. Is is just the small case design meaning that the rear bearing isn't big enough to take the beating, or is there something else to it?
Old 09-24-2020, 06:27 PM
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we Heli guys went threw that way back with the OS Hyper 50. is there a brand name on the stock AX rear bearing. if not then that's your answer. when you replace the bearing buy SKF bearings

Jim
Old 09-24-2020, 09:52 PM
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OS uses substandard bearings. Most of their modern engines eat bearings. Not every one, but many.
Old 09-25-2020, 09:29 AM
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I fly SPA where the .65 AX is pretty much the standard engine. Even the guys who replace with Boca bearings say their engines run through bearings faster than any other.
Old 09-25-2020, 10:57 AM
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I replaced bearings in 2 Hyper 50 at the same time, I order a NTN rear and a SKF rear. I tell you that the SKF was smother (in the hand).

Jim
Old 09-25-2020, 12:10 PM
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That and crap lubrication

When I switched to Byron Rotor Rage I quit putting bearings in my Hyper 50's
Old 09-25-2020, 05:12 PM
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Originally Posted by BarracudaHockey View Post
That and crap lubrication

When I switched to Byron Rotor Rage I quit putting bearings in my Hyper 50's
oil sure can make a difference. I was burning Magnum. I have been wanting to change, but I still have fuel.

Jim
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Old 09-27-2020, 05:08 AM
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Originally Posted by jester_s1 View Post
I fly SPA where the .65 AX is pretty much the standard engine. Even the guys who replace with Boca bearings say their engines run through bearings faster than any other.
I think that tells you a bit about the bearings OS uses and Boca supplies. This subject has come up time and time again on many forums. The answer is a quality true C3 fit bearing. The very best bearings are Swiss WIB Bearings (IMHO). Ive replaced NTN, SKF, and even some FAG and NACHI bearings. The biggest problem with bearings is quality lubrication. The next biggest problem is rust protection. No bearing is immune from these damages. However - these problems are secondary to improper fitted clearance (not C3).
Old 09-27-2020, 10:10 AM
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Exactly correct on the off brand , off grade bearings. Another good brand you can still find on shelves is NDH known as New Departure Hyatt. A C-3 clearance listing on a no name bearing is little more than a letter and number.That C-3 is just a starting point. No consideration for race and ball surface finishes in the "C-3" spec.
I totally agree regarding installation and fit as well. Bearings installed with excessive internal clearances are doomed to a short life. The average RC modeler is an assembler but not a fitter.
Old 09-27-2020, 04:22 PM
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So Jesse Open, what else should a guy do besides heat the case, slide the crank in, spin it a few times to check alignment, and let it cool? What fitting is needed?
Old 09-28-2020, 06:01 AM
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Thank you

Just one among many is to check the running clearances . As alluded earlier, quality control on no name bearings is poor. Excessive internal clearance is a major cause of early bearing failure.




Last edited by Jesse Open; 09-28-2020 at 06:03 AM.
Old 09-28-2020, 11:02 AM
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Originally Posted by Jesse Open View Post
Thank you

Just one among many is to check the running clearances . As alluded earlier, quality control on no name bearings is poor. Excessive internal clearance is a major cause of early bearing failure.

in other words, see if the bearing turns true and not off center.

Jim
Old 09-28-2020, 12:36 PM
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No
Those are your words. Nothing to do with mine




Old 10-10-2020, 11:25 AM
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Can one of you guys recommend a vendor for either the SKF or NDH bearings? The project has been on the shelf for a bit, but I'm back to it. I searched a few sources and they either only list them by part number or don't have the right sizes available.
Old 10-17-2020, 05:48 AM
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There are other quality bearing manufacturers that can be had. Do some googling with a manufacturer and bearing number or size for search keywords. Nachi, FAG, SKF, WIB, etc are some of many options. I prefer Swiss WIB Bearings myself - these are what Picco installs into their engines at the factory. They are stellar quality. I have used cheap Chinese no-name Bearings with success, but I only use those in pedestrian engines.

If there isn’t a brand and Country Of Origin stamped on your bearing, you likely have a chinese no-name POS.
Old 10-18-2020, 06:23 PM
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higher quality bearings stabilize the crank more.

to prove the point I once bought 2 WIB for the main shaft on my .50 Heli, what a difference, smother, smoother, smoother, quicker and faster.

Jim

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