How Do You Know When A Bearing Goes Down??

[hshooman]

I realize that there are many bearings on our helis, but how can one tell when one goes down?? Are there any tell-tale signs?? Do they make noise? Do they seize up?? I have yet (I think) to have one quit on any of my birds??

[rudyy]

If you can feel the notchiness, it is time to replace them. Some bearings wear so badly that it becomes visually noticeable without feeling the notchiness. For example, the tail shaft bearings or torque tube bearings could cause a lot of draggings. The main mast bearings could cause a FBL unit to act weirdly.

[svensson_bo_l]

Originally Posted by hshooman

I realize that there are many bearings on our helis, but how can one tell when one goes down?? Are there any tell-tale signs?? Do they make noise? Do they seize up?? I have yet (I think) to have one quit on any of my birds??

Long time ago, from a skilled car mechanic I learned to look for two things:
1. Put a shaft that fits the inside. Use the shaft to roll it over a sensitive part of a finger. If you feel anything but soft roll, replace it. This is the notchiness ruddy pionts out.
2. Feel for any slop. Any slop at all, trying to softly move the shaft perpendicular to the length of the shaft, replace the bearing. A evenly weared bearing can have slop without being notchy.

In helis my experience is that, after a crasch, you are likely to find notchy bearings. Even if it feels like little, they will degrade fast, so when in doubt - replace.

Regards,
Bo

[TucsonFlyer]

The above is exactly right. The only thing I'd add is before you check a non-sealed bearing, clean it out and regrease it if possible especially if you live in a dusty area.

I've had several instances where I'd have a crash and got lots of dirt in my main and tail grip bearings and they felt really nasty until I cleaned them thoroughly and regreased at which point they turned out to be just fine.

[spykez]

The smaller your heli (the smaller your bearings), the more likely you are to trash them in a crash. They also die of wear quicker.

Forgone conclusion on my 250 because of the high speed - grip and main shaft bearings usually get knackered.

Less frequent on the 450's. But still happens.

My mini protos unthrusted tail - when it becomes unpredictable, that's when I know I have to change them out.

When motors sound sick, that's another thing.

Oddly, nano and mCPX bearings can last for quite a while longer than 130X and 250 bearings - I guess the the former are much lighter.

[svensson_bo_l]

Originally Posted by TucsonFlyer

The above is exactly right. The only thing I'd add is before you check a non-sealed bearing, clean it out and regrease it if possible especially if you live in a dusty area.

I've had several instances where I'd have a crash and got lots of dirt in my main and tail grip bearings and they felt really nasty until I cleaned them thoroughly and regreased at which point they turned out to be just fine.

Good that you bring up cleanness!

I fly in relatively clean environments only.
Fortunately most of our bearings, except thrust bearings and OWB are protected.
That does not mean they are safe in a dirty or dusty environment.
Taking a head or tail apart means clean thrust bearing (I use gasoline), let dry, grease and reassamble.
With some 2200 flights on a few helis I never replaced a thrust bearing so far.
All work with bearings should take place in a clean environment.
Bearings that are not lubricated die fast. An oil film, from oil or grease, prevents metal from touching metal.
If no lubrication is available, metal reach metal and it will go downhill in no time…

How often do you need to take a head apart for cleaning and regreasing?
I don't know, but would estimate some 150 flights? Anyone else?

Regards,
Bo

[btheli]

My input to one of the OP's questions is that a bearing will usually squeal when it's failing. Not always but usually. Once you hear the squeal, then you know to check what the other posters said.

Another strategy is to replace all the bearings every season and after crashes.

[Icanfly]

notcheyness, rattling, loose play, side to side twist, rattling, motor noise, quirky controls and gyro response, vibes, ???????? and generally can look ugly and old.

I recently put fresh bearings in a nitro os32 rebuild and they SING like the motor after a porting and bearing re+re, and even have a new season bearing set when a new ring is located, some things just don't last in certain environments like high rp. Take the tail slider bearings on a 450, THEY will wear out as mine have with too much twist and side play.

bearings?, heli git yours, lol.

[hshooman]

Thanks for all of your suggestions. I will put them to good use.

[Atomic Skull]

Originally Posted by svensson_bo_l

2. Feel for any slop. Any slop at all, trying to softly move the shaft perpendicular to the length of the shaft, replace the bearing. A evenly weared bearing can have slop without being notchy.

Even brand new from the tube all micro bearings have some small amount of slop to them, especially angular slop.