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A year ago, I cleaned out all the bearings in solvent, removed ALL old grease, and repacked with Red Line CV-2 synthetic grease. The bearings have 300k miles, give or take.

My car has taken to whining at highway speed, and the whining reduces a lot when I turn a certain direction. It really sounds like it's coming from the back, so I pulled the bearings for a looksy. Both sides rolled free with the car in the air. Left side bearings looked great, here is the right.

Outer bearing (smaller)

The roller surface has a gray stripe in the middle, but the grease looks completely healthy. It looks tan because it was shot under HPS lights. The inner race looks OK.

enter image description here



Inner bearing (larger)

The roller surface seems ok, the outer race looks fine, but the grease looks filthy and muddy. Again, brand new grease. It's all over the bearing like the bearing is causing it, but could it be something else like water ingress from a failing lip seal? What's wrong with it?

enter image description here

The spindle looks great, with no obvious slipping.

I have spares of everything. Which ones if any need to be replaced?


Edit: It turns out I was looking at the wrong side. On the left side, I found the nut much looser than I had set it. It had a muddy inner bearing (from an ancient lip seal leaking; replaced) and a weirdly dirty outer bearing. (my grease is Red Line, literally red, so I can instantly spot dirty grease). I dunked the inner bearing in solvent for cleaning, fished it out with my finger and repacked it. Dunked the outer bearing, fished it out with my finger, repacked it. Put it on, it was weirdly grindey with inner bearing installed. .

So I got another bearing from a junkyard pull, test fitted it and it ran smooth as glass. I dunked it in the same solvent, and fished it out with a screwdriver this time. The screwdriver came back covered in metal shavings. I could not believe so much metal shavings could come out of one bearing. Wait. Did this metal come from the original bearing or the junkyard pull? Then I cleaned the solvent, re-dunked the junkyard bearing until no more metal shavings appeared. Repacked it, put it on the car, smooth as glass.

Now I've re-solvent-washed the original outer bearing, a little more metal shaving showed up (a-ha!!!!) Clean/dry/in my bare hands it runs VERY lumpy with a little pressure. It didn't look all that bad on the rollers and races.

So I think that was my problem. Yay, I'm about to do a 3000 mile cruise!

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  • Side comment - sunlight is the best source of light for photographing where colour may be important. If you can photograph the item in direct sunlight, most cameras get a good output.
    – Criggie
    Sep 26, 2020 at 6:33
  • @Criggie Yeah I also have a very over-lit office right next door with 90 CRI "New Fluorescents" that I am very proud of, so I have no excuse lol... Oct 27, 2020 at 22:51

3 Answers 3

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Both bearings show a wear strip - this is normal.

The grease that is milky or grey has been contaminated and needs replacing.

On my 4*4 I used to clean and repack the bearings then set the play very carefully. They lasted for years with no problems with exactly that middle strip wear pattern.

Inspect carefully - any chips or cracks on the rollers means time for replacement.

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  • I've thought it could be a worn out lip seal letting water in... but that wouldn't explain why it makes excessive noise or more/less noise during turns. Sep 25, 2020 at 14:07
  • Have you cleaned them?
    – Solar Mike
    Sep 25, 2020 at 14:09
  • Not yet, I don’t have quality replacement grease on-hand. I'll get some. I repacked last year when the noise problem was not so bad, hoping grease condition would tell the tale. Is a dual failure possible, this bearing being fine and another bearing accounting for the noise? Sep 25, 2020 at 14:12
  • The noise on turns could be related to preload - you need goldilocks (enough but not too much.) Or you're turning on full wheel lock and perhaps something's rubbing. Get the front end up on axle stands, spin the wheels by hand while someone turns the steering wheel to full lock. If the bearings were causing the noise it would be there on straight-ahead too. However slightly-loose bearings could cause noise too.
    – Criggie
    Sep 26, 2020 at 6:36
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Not sure how either blacksmith or Mike came to their conclusions ... you cannot tell much about a bearing until the grease is removed. Grease will tell some of the tale, but it has to be cleaned for the bearing to give you the full story. Then you can look for discoloration in the bearing (blueing due to heat) and also run your fingernail across the roller surface and detached race to see how much scoring is actually there. If your fingernail catches at all, then it's time for replacement (or blueing is present as I already stated).

From what I can see there isn't any issues with the bearings, but really they need to be thoroughly cleaned, inspected, if no issues found, repacked, and then put back into operations. If issues are found, then you would replace.

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  • A bearing can be sufficiently damaged undetectable by a fingernail...
    – Solar Mike
    Sep 25, 2020 at 19:30
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    @SolarMike - Other than destroying the bearing, pulling it apart to mic the entire thing, there's not much else you can use. You surely cannot tell what's going on without cleaning them. Use what's at your disposal, which in this case is a fingernail and your eyeballs. Probably the best tools for the job. Please post up if there's some other way to tell. Sep 25, 2020 at 20:05
  • Humans can feel surprisingly small surface features. Like 10μm or even less.
    – Michael
    Sep 26, 2020 at 19:34
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Both bearings are gone. The tan grease looks more like water emulsified into the grease. One thing that causes a grey/cloudy is abrasion / dirt in the bearing. Maybe it is corrosion, would fit with water in the grease . Electric discharge can cause a "frosted" surface , but I doubt that is the problem. I would replace them and the seals and see if that fixes the situation. A good rolling element bearing should show nothing ( but shiny 52100 steel) on the wear surface. SKF and others have internet sites if you want to find why your bearings failed. Don Wulpi book ; "How components fail " is good but I see it is now expensive. He background was with International Harvester many years ago, so not a computer geek professor.

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  • The "tan" grease is actually a healthy translucent red. The tan look is from the sodium lights. I tried to color-correct in Photoshop but that isn't really possible. It's the other bearing with goobed up water contamination. Sep 25, 2020 at 19:42
  • And there is different greases on the inner and outer races ? Wearing my Amoco hat- you need new bearings to run 24 hr,360 days a year. For myself I might try to get a few more miles from them. Sep 25, 2020 at 21:46
  • No, it is identical Red Line synthetic grease. Sorry the picture is so ratty, the shop has sodium lights and the phone camera does not like them. Sep 25, 2020 at 23:03

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