OS 50 rear bearing, some one link me to a good deal

[cripskillz]

OS 50 rear bearing, some one link me to a good deal for a good bearing.

shankz
crip

[AlanMcSwain]

Cripz...

Most of the posts I've seen on this issue have people putting in ceramic bearings from Boca Bearing in FL.

Alot of guys are also grinding off that damn crank web so the bearing is lubricated in a more conventional manner. Most say the engine runs smoother and the bearing life is dramatically extended.

Alan

[cripskillz]

I think its all BS

there was plenty of oil in the bearing there is no need to cut the webbing at least not so oil can get to the bearing!!

later
Crip

[Heliguy]

The point is so the bearing is not swimming in oil to the point were it floats :idea:

[Matthew]

Piss on all that ceramic grinding and stuff. If you need new bearings buy the stock ones or it's equivalent and fly. Burn nitro and put raftering oil in afterwords. Good maintenance will keep that engine running for a long time and you can use the extra $$$ to buy more fuel. Just my thoughts.

[cripskillz]

Humm never heard of to much oil ruining a beraring

Id like to see your reasearch on that one!!!

[fitenfyr]

No link, but...
McGuire Bearing here in Seattle is where I got mine.
They are a steel cage bearing unlike the plastic cage in the stock one (my theory as to why they are failing)
Seattle phone number (206)767-3283.
I paid 14.40 out the door for 2 of them.
So far so good, but I only have a couple tanks on it.
Very solid looking and smooth feeling bearing.
I think they are NTK brand.

[cripskillz]

thanks J

but ill have to go against that theroy

because mine was makin noise I pulled it instantly

the plastic cage is just fine no dammage

the whole bearing looks great but you can feel and hear the nastyness

and the plastic is still intacted

I also just got a stock replacment so I no longer need links

thanks guys

[Inspector Fuzz]

@cripskillz,
Apparently, too much oil does kill bearings.. The balls somehow "hydroplane" up onto the oil film and are able to slow or stop their spinning.. This phenomenon usually occurs during a lightly loaded portion of the stroke.. When the load becomes heavier, the bearings crash down (like tires on a runway) and "skid" a ways before they are up to speed spinning.. Do this a few hundred thousand times and you have a worn bearing.. Consider how unbalanced the OS 50 is and you can see how the loaded/unloaded oil drowned bearing destroys itself..
A guy named "Doug" over on RR actually identified the phenomena.. JEFF

[Inspector Fuzz]

@cripskillz,
Apparently, too much oil does kill bearings.. The balls somehow "hydroplane" up onto the oil film and are able to slow or stop their spinning.. This phenomenon usually occurs during a lightly loaded portion of the stroke.. When the load becomes heavier, the bearings crash down (like tires on a runway) and "skid" a ways before they are up to speed spinning.. Do this a few hundred thousand times and you have a worn bearing.. Consider how unbalanced the OS 50 is and you can see how the loaded/unloaded oil drowned bearing destroys itself..
A guy named "Doug" over on RR actually identified the phenomena.. JEFF

[Todd Marsh]

I had a OS50SXH that I ran 8-10 gallons through, without even a little noise out of the rear bearing at all. But Ive seen WAY too many posts on OS50 rear bearings going bad, to say its isolated, I must have just gotten lucky. It was actually the first, and only ringed engine, I had ever owned, and it ran stronger when I sold it then when it was new! Also, my engine was mounted somewhat unique, in that it was upside down, with the crank/fan facing out the back of the heli, so maybe thats why my rear bearing wasnt "bathed" in oil. Sure did have a tendency to flood easy with the piston cylinder facing down though, so it was a real PITA to start.

[Doug]

They are a steel cage bearing unlike the plastic cage in the stock one (my theory as to why they are failing)

High speed ball bearings need to have very low cage inertia and also a cage which is "fatigue proof" that is why the "high" speed bearings (including the stock OS) have the plastic cage.

The real problem is lack of pre load which can allow skidding either due to excess oil or "feedback" vibration (soft mounting) ( the web mod addresses both problems). Oil can no longer be trapped in the outer race and the change in balance makes the resonance of the engine less of a problem.

[Kinger]

Hey Cripskillz - How many gallons did you have on your engine before the bearing went kaput?

[Kinger]

Well, looks like my rear bearing may have went south in my OS50 now. Only 7 gallons through the engine and it was NEVER run lean. This sucks..........

[megarckid]

well i have to put my 2 cents in the pot :mrgreen: i have a os 50 sx-h i ran 2 gallons and kept the temp around 180/200 deg, never ran hot. and the eng started to sound funny and not funny ha! ha! but funny :)tore it down and the connecting rod was starting to grind the bottom of the case. come to find out the rear bearing was going out on me. good thing i checked it because it had broke the ring too. dew to the debris from the bearing. so you guy's can say what you want. but i have seen to many go bad stock and every body that has done the mods hasnt had any problems at all. one guy said he has 25 gallons threw his so i geuss its what ever you think on this topic

[megarckid]

well i have to put my 2 cents in the pot :mrgreen: i have a os 50 sx-h i ran 2 gallons and kept the temp around 180/200 deg, never ran hot. and the eng started to sound funny and not funny ha! ha! but funny :)tore it down and the connecting rod was starting to grind the bottom of the case. come to find out the rear bearing was going out on me. good thing i checked it because it had broke the ring too. dew to the debris from the bearing. so you guy's can say what you want. but i have seen to many go bad stock and every body that has done the mods hasnt had any problems at all. one guy said he has 25 gallons threw his so i geuss its what ever you think on this topic

[the collective]

I did the crank mod on my 50 and have about six gallons through it since. The engine started sounding pretty funny recently, I took it apart and the rear bearing is completely toasted. Very sloppy and it feels awful when turning it by hand.

I don't think the crank mod is responsible for the problem, the motor has been through two pretty good crashes, it did overspeed during both, so I expect at least some of the bearing problem to be from the overspeeds.

I've got a Boca ceramic bearing on the way, it'll go in tomorrow. Hopefully the engine will come back to life, the bottom end of the conrod did show some marking where it rubbed the case due to the slopped out rear bearing. The conrod to crank fit is fine, as is the wristpin fit. The piston and ring look good, but I might go ahead and put a fresh ring in there.

THe motor has been a powerhouse, and with the crank mod it ran noticeably smoother than new. It'll also get a ST carb when it goes back together, the 40E with the cateye mod has been running well, but the ST looks to have a larger bore so I'm hoping to pick up a bit of power with it.

Will let everyone know how it works out once it's back together.