Interesting Markings on Trailer Bearings

[C_M_25]

Hey guys. It's a rainy day here in oklahoma, so I'm taking the day to clean the shop. I came across a box of two hubs, so I took a look and realized they are the hubs that I pulled off the trailer last year after having some issues and forgot to clean. Seems like the perfect project for a rainy day.

Now, you guys have followed my trailer woes for a while, and it is the main reason the boat sits on a lift now. I blew some seals, had to get a new (proper) trailer for my boat, then had water in the hubs, etc etc. Prior to driving the boat to keystone, I put on 2 new hubs on one side of the trailer because of a few issues. I noticed about half way on my trip that two seals had spit out some nasty black stuff on the back of the hub. I continued on, the hubs never really got unusually hot, and then swapped out those two bad hubs with rebuilt hubs I had available. No sweat.

Today I decided to clean those 2 bad hubs up finally. I noticed that the cherry red grease was very dark and smelled burnt. Keep in mind that everything was new when I installed before that trip. I cleaned everything up and I noticed the weird markings on the bearings you see in the pictures. You can see that the rollers look like new, but the inside of the cone has some wear markings right next to the rollers. The races are super smooth, but I could argue that they may have some discoloration closest to the center of the hub. If things overheated in the hub, I imagine this is where things got hot. Any chance these markings could be a sign that the hub was installed too tightly (too much preload by me)? Let me know if you have ever seen this before.

[MH Hawker]

it looks like some sort of pitting to me not water more like some sort of hard contaniment

[r&s20]

Yes, I have seen marks like these before. I usually see these types of markings on inferior bearings. if you look at the smaller end of bearings there are wear marks around bearing but not at big end. that lends to bearings not running true on race.

[rickpo]

Looks like some of them chattered. Ouch

[ralph]

CM25,

Looks like what we call in the bearing world debris denting on the rollers. This is caused from debris within the hub from perhaps the spindle. It also can be from contamination introduced while installing these bearings (most likely).

The rollers do look like they still have lube on them in the pictures. I'd like to see more pictures after they are completely cleaned out. Also I would like to see pictures of the raceways of the cups (outer rings) all cleaned up of course.

When you are installing bearings there are a few rules that should be followed to prevent debris denting.

1 - Never take the bearings out of it's packaging until you are ready to install them (keep them clean)
2 - I know that many will lube the bearings by hand, packing grease into the cages and around the rollers. If you do this make sure your hands are CLEAN, CLEAN, CLEAN.
3 - Keep work area where you are doing the install clean
4 - Completely clean out the hub prior to installing the bearings
5 - No grinding of anything around the bearing or grease. That stuff gets into the air and into the bearings and perhaps grease.

See if you can post pictures after everything is cleaned out if that is grease on the rollers.