Bearing & Race Inspection

[scottz]

I'm in the process of re-packing my wheel bearings. The inner & outer bearings and the outer races look great, but 3 of the inner races have some dark marks on them. I'm not sure what these marks are. The race feels smooth. These bearings have about 28k miles on them.

Should I replace the inner bearings and races?

[MandK]

It looks like moisture etching. Lines on the races look to match up with roller spacing. If it is perfectly smooth, you can probably get by but pay particular attention to the surface of the rollers where they were in contact with the races when it made those marks. It happens when the unit sits for a while. You may find matching marks when you clean them up.
For the relative inexpensive cost of the bearing sets, I’d replace them.

[MandK]

Just noticed that your trailer is a 2017, you pull quite a bit, I’d certainly replace them.
I use to see that on heavy trailers ( low boys, etc) in the construction related business I was employed in but we didn’t use some of those trailers all that much. You can find info by searching tiimken bearing analysis online

[AZ Traveler]

Scott,

If they are smooth, you should be OK to continue with them. Did you replace them when you added disk brakes?

[Ram Montana High Country]

I was surprised the other day, bought bearings for my Ford at the parts store, NO rases included in the box ... hate cost reductions. Since I stuck it in my low mileage truck, stuck them in and on we go.

Food for thought

[scottz]

Originally Posted by AZ Traveler

Scott,

If they are smooth, you should be OK to continue with them. Did you replace them when you added disk brakes?

Yes. I have the hubs with 9/16 lugs and the larger bearings. I've put about 28k miles on it since I installed disc brakes in April 2018. As a side note, the brake pads look great; probably 80%.

[scottz]

Originally Posted by MandK

It looks like moisture etching. Lines on the races look to match up with roller spacing. If it is perfectly smooth, you can probably get by but pay particular attention to the surface of the rollers where they were in contact with the races when it made those marks. It happens when the unit sits for a while. You may find matching marks when you clean them up.
For the relative inexpensive cost of the bearing sets, I’d replace them.

That is what I was thinking; probably where it sits all winter. I wonder why the outer bearings don't show any marks?

[Dave W]

Moisture - maybe but that would tell me that there is a breakdown/separation of the grease you used. Without knowing the brand, it should be NGLI #2, high temperature, lithium complex according to the Dexter on line bearing information. They also have a recommended brand name chart



Have you had welding done on the trailer? I have seen this after welding was done to install a trailer hitch, i.e. my ancient and long gone 1976 F250

[scottz]

I ordered new bearings. I don't think there is anything wrong with these, but, for $80 it is not worth worrying about. I can feel a very slight texture change on some of the dark spots. Getting out my brass drifts and BFH; since I'm truckless now, no rush.

Thanks for the help.

[rohrmann]

Races rarely if ever come as a package with the bearings. I think there could be different races that would work with a particular bearing, depending on the bore of the hub the race would be installed in.

[scottz]

I ordered bearings and races.

[scottz]

Originally Posted by Dave W

Moisture - maybe but that would tell me that there is a breakdown/separation of the grease you used. Without knowing the brand, it should be NGLI #2, high temperature, lithium complex according to the Dexter on line bearing information. They also have a recommended brand name chart



Have you had welding done on the trailer? I have seen this after welding was done to install a trailer hitch, i.e. my ancient and long gone 1976 F250

Yes, in the summer of 19 Henderson welded on new spring hangers; so maybe. The grease I use is lithium based NGLI.

[dfb]

anything other than a nice smooth machined surface is 86d..

[scottz]

Originally Posted by dfb

anything other than a nice smooth machined surface is 86d..

New bearings and cups arriving tomorrow.

[Gregg]

Originally Posted by scottz

New bearings and cups arriving tomorrow.

What you are seeing is black acid etching. It is caused by moisture mixing with extreme pressure additives in the grease at temperature chemical reactions take place. Then whe it cools the mixture condenses into phosphoric acid. If reused they will start pitting and ultimately fail in not that many miles. I have been doing and teaching failure analysis for 40 years.

[scottz]

Originally Posted by Gregg

What you are seeing is black acid etching. It is caused by moisture mixing with extreme pressure additives in the grease at temperature chemical reactions take place. Then whe it cools the mixture condenses into phosphoric acid. If reused they will start pitting and ultimately fail in not that many miles. I have been doing and teaching failure analysis for 40 years.

Thank you, that is exactly what I needed to know. Any idea what can be done to prevent it? These bearings are 3 years old and have about 28k miles on them.

[ChuckS]

Just looking at the grease Im guessing thats Lucas Red & Tacky... an excellent grease and ALL I have used for decades on my RV wheel bearings and suspension..

What I do see though is OLD grease .. looking at the color.. If the bearings are packed once a year ..by hand that Red & Tacky grease should not look like what I see on the edges...

A set of races and bearings are usually matched.. thats how I buy bearings and races...

If the RV sits for long periods then the grease is wicking away a bit and you get the Fretting that I see ...

Its cheap insurance to replace .. and since you have the skill sets to do it yourself tis what I would do...

[scottz]

Originally Posted by ChuckS

Just looking at the grease Im guessing thats Lucas Red & Tacky... an excellent grease and ALL I have used for decades on my RV wheel bearings and suspension..

What I do see though is OLD grease .. looking at the color.. If the bearings are packed once a year ..by hand that Red & Tacky grease should not look like what I see on the edges...

A set of races and bearings are usually matched.. thats how I buy bearings and races...

If the RV sits for long periods then the grease is wicking away a bit and you get the Fretting that I see ...

Its cheap insurance to replace .. and since you have the skill sets to do it yourself tis what I would do...

The only grease I have used on those hubs since new when I installed disc brakes is O'reilly's Master Pro. Red, EP, NLGI GC-LB; it seems to have the same specs as any disk brake wheel bearing grease. However, maybe it's breaking down. As a precaution, I purchased a tub of Valvoline EP NLGI-2 GC-LB.

The longest it sits is three months. Still wondering why the outer bearings look great. Probably has something to do with the inner bearings carrying most of the weight; the reason they are bigger.

Thanks for the help.

[Gregg]

Originally Posted by scottz

The only grease I have used on those hubs since new when I installed disc brakes is O'reilly's Master Pro. Red, EP, NLGI GC-LB; it seems to have the same specs as any disk brake wheel bearing grease. However, maybe it's breaking down. As a precaution, I purchased a tub of Valvoline EP NLGI-2 GC-LB.

The longest it sits is three months. Still wondering why the outer bearings look great. Probably has something to do with the inner bearings carrying most of the weight; the reason they are bigger.

Thanks for the help.

I also use Lucas Red &Tacky very good grease. The reason for inner bearing is it is next to the seal. Most probable cause is during operation the bearing and grease heat, ( brake heat migration) grease expansion results, expelling some grease and/or air. Then if you hit a water hole, rain it rapidly cools the bearing area and grease creating a vacuum in the bearing cavity pulling a slight amount of water in by the seal. There is really nothing you can do to prevent the process. Clean grease on a regular basis. That is the theory of the easy lube axles. As you pump grease in. It enters the area between the inner bearing and seal flushing the contaminated grease. However with drum brakes that in itself is a problem

[scottz]

Thank you.