O.S. .46 AX Replacement Bearings - remove shields?
 

Ordered a replacement set of bearings for one of my O.S. .46 AX engines. I am curious if I should remove both shields on the rear bearing and the inner shield on the front bearing?

Front: R6Z
Rear: 6902

http://somegeek.home.comcast.net/som...x_bearings.jpg

Good deal for $7.86 shipped.

somegeek

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

G'day Mate,
YES.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

Right on - thanks man. :D

somegeek

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

I generally don't worry about pulling one of the shields on the front bearing -- the oil gets past them just fine anyway -- but it's a good idea to pop both shields from the rear one - or just buy unshielded bearings in the first place. I get mine from RC-Bearings.com and the rears come without shields -- and they have a polymer cage as well which is a *lot* safer for your engine.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

As it related to seals, the decision is a bit more complex...

It is only in regards to the front bearing.


If your front bearing is a grease-packed, double sealed one that is capable of running at the engine's intended RPM range (grease-packed bearings are more RPM limited, compared to open/shielded bearings), just leave both seals in.

Don't remove the rear seal, since the bearing does not need the engine's lubricant to run.

It is greased for life.


As to RPM limits; with oil-spray lubrication, an R6-Z/ZZ/open bearing can run at 36,000 RPM.

If grease-packed, the limiting RPM is reduced to 29,000 RPM and with contact-seals (friction), this number is reduced even further, to only 20,000 RPM.


For the RPM range of the OS.46AX, none of these limits apply, since it will never be run at over 17,000 RPM; even if spinning a toothpick prop...

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

IMHO the shields would keep the cages IN the bearing if failure occurs,I say this because I have a 46fx that digested a front cage and its not pretty. (scored crank,grooved block)

this is not to say that with the shield it would be bullit proof but maybe it would give you some hint of trouble before breaking loose.

rubber seals are different than shields.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

Quote:

---

ORIGINAL: craigpuckett

IMHO the shields would keep the cages IN the bearing if failure occurs...

---

This is highly unlikely, Craig.

If the cage disintegrates, the spinning balls and fragments would likely pop the shield off.


This is the very reason RC-Bearings now supply all their rear bearings with a phenolic/polyamide cage.
If the cage happens to shrapnel, the pieces are less likely to damage the piston and the sleeve...

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

From my experience, on a shielded bearing and you loose the cage, all the junk goes up through the engine just like on an unshielded bearing.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

experience rules,I stand corrected[8D]


I haven't tried the shields, just wishfull thinking on my part I guess [:o]

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

The broken metal cage ultimately ends up as little fine metal particles and these come out from under the lip of the shield and seal also if that's the kind of bearing it is. These migrate up on the cylinder wall and gall the piston skirt and cylinder wall. Makes a mess.

As soon as you hear or feel the bad bearings, you should change them.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

Good to hear - that is where I am now... just a bit of noise compared to another AX of mine which is smooth.

somegeek

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

I wouldn't hesitate inspecting bearings as soon as they felt gritty, ran hot, made noise, or had excessive play. The potential for a lot of damage is too high to procrastinate, IMO. OS parts like liners and pistons are extremely expensive.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

Quote:

---

ORIGINAL: w8ye

As soon as you hear, or feel the bad bearings, you should change them.

---

This is very true with normal bearings.

With ceramic bearings, however, you might hear them even when they are brand new.

They are generally a bit more audible.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

So true.

A guy turned up at our field with *three* engines that all had bad bearings. He'd used CoolPower for less than a month and they'd all rusted badly -- go figure.

It took me about 15 minutes to change the bearings in one of his engine so he could fly.

Fifteen minutes of time and $7 worth of materials is a small price to pay to ensure an engine isn't ruined in the blink of an eye.

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

The below statements only apply if it's a plastic or phoenolic retainer. The metal retainers are guaranteed to explode long before you reach those rpms.

I would never take a metal retainer over 20k myself. I've seen way too many explode in the mid 20s and up.


Chris

RE: O.S. .46 AX Replacement Bearings - remove shields?
 

....that's normal for CruelPower. :)