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Wingeezer · 08-19-2012, 05:06 PM

I bought a spare set of bearings (and seals) just to carry in our trailer as a precaution - I figured it might be good to have a set on hand rather than to try and find them is I discover troubles on the road.

I generally check all the bearings during our cross country trips at each gas and pee stop, either by hand feel or with an IR thermometer

When I ordered the bearings through an AS dealer, I had to order the inner race/cage separately from the outer race.

That surprised me a bit, because In the past, whenever I ordered wheel bearings, I got them as a set - ie the outer race was matched to the inner race & cage.

I always assumed that tolerances were very close and they had to be a matched set. From my experience in ordering from AS, it seems that is not so.

That leads me to a second question.

I just repacked my bearings. on one out of four wheels, after I cleaned the bearings, I noticed that one of the outer races exhibited very slight circumferential marking on the rollers. They were very minor and you certainly couldn't feel them with your fingernail - they were barely there.

There was no indication whatever that the bearing was breaking up, (as I have seen on other trailer bearings that I have dismantled!)

There were no markings at all on the outer race, and the inner race felt perfectly smooth when rotated.

I opted to repack and re-use it, but to keep an extra close watch on that hub. In hindsight I'm not sure if that was a good call or not!

I'd be interested in your thoughts if you are more experienced that I on this sort of thing!

But also, I'd be interested in knowing - if you opted to replace the bearing, would you automatically also change the outer race as well, even though it looked perfect?

I would have thought so, but the fact that AS sells the races separately makes me think that maybe it wouldn't really be necessary - else why would they sell them separately?

Brian.

Gene · 08-19-2012, 05:46 PM

Since I've experienced bearing failure on the road, my feeling is to replace the race at the same time as the bearing on that wheel. The parts are pretty cheap, so why not?

These are pretty standard parts and you can get them at aftermarket auto parts stores.

Gene

TBSarfari28 · 08-19-2012, 06:27 PM

Brian,
Here is some info on bearing adjustment and failure causes and re-use guidelines. All anti-friction bearings are manufactured to ISO and the Anti-Friction Bearing Manufactures Association standards, so you can purchase them from bearing suppliers and Auto Parts stores as Gene stated. Mixing used cones and cups with new is commonly done as long as the used part is still good.
http://www.koyousa.com/brochures/pdf...re%20chart.pdf
http://www.timken.com/EN-US/products...ments/6347.pdf
Automotive TechTips (North America)
Good Luck.
Tom

dwightdi · 08-19-2012, 06:58 PM

Roller bearings fail in various ways depending on the load, lubrication and fatigue. They do not last forever. If any signs of failure showed on any parts, I would change all parts. I check bearings whenever, I check the brakes. I put a write up on our unit website at Northern Illinois » Maintenance There is quite a bit of information there from the various bearing suppliers. I do carry spare bearings and dual lip seals with me on the road.

SafariSS · 08-19-2012, 07:24 PM

Since so much is riding on the bearings I wanted to replace my 6 year old well maintained bearings. I could not find anything but Chinese bearings which look so cheap, the cage looks like it is cast pot metal. Anyone found good brand bearings? Koyo, Timken or FAG bearings?

polarlyse · 08-19-2012, 10:01 PM

I have not felt the need to replace bearings yet. Inspection prior to re-packing had shown mine to be in good shape but if I felt the need I would only replace the whole shebang to include inner / outer bearings AND races. When I replaced the seals I kept the old ones for emergencies.

noreen&sal · 08-20-2012, 04:03 AM

I agree with Roger. If the bearings are worn, so are the races. Sal.

Wayne&Sam · 08-20-2012, 04:40 AM

I think that maybe manufacturing tolerances are much better than they were in the old days, so as long as both bearing and race are new, they are "matched". But once they are used and start to wear, an old race and new bearing won't be a good match. Go all new.

MrBeast · 08-20-2012, 05:29 AM

Here is my .02 on wheel bearings. usually during normal business hours it is easy to get a set of bearings for your rig.

However seeing as how Mr. Murphy has often been my co-pilot, I have never had a wheel bearing fail when I was close to home, in a good place, or at a time of day when the trailer supply place was open.

Something to keep in mind, many auto parts stores have auto parts, but when it comes to trailer parts, they can order what you need in 1-3 days. Depending on where you are, break down on a Saturday afternoon, it may be Tuesday or Wednesday afternoon before you can have a new set of bearings in hand.

Carrying an extra set with you is good insurance. keep in mind however if they are just in the cheap cardboard box they came in, well as they ride down the road in your trailer, they are going to get bounced all over heck, and this can damage them.

I can think of few things that would make for a long day like being stuck on highway 93 somewhere between Wells and Las Vegas with a burnt out bearing, only to find your "new" bearings were damaged in the box and are now an exercise in futility.

Thus keep extra bearings with you, and protect them. wrapping them in and old wash cloth and putting them in a Ziploc bag or small coffee can will do wonders for this. If you wanted to go really nuts you could pre-pack them at home, put them in the ziplock, then wrap them with the wash cloth and then you aren't standing on the side of the road trying to pack a bearing.

Also, wheel seals, this is just a great thing to bring double extra of. they are less than 5 bucks each, and they are really easy to destroy when you are installing them. Which if you are on the side of the road 500 miles from home, you probably didn't think to bring a wheel seal installation tool with you.

Your best insurance however is replacing that bearing with your trailer comfortably parked in your driveway. If there is any doubt to thier condition, you can buy all 4 bearings, seals, grease and a pneumatic packing tool for less than 100 dollars, If you find yourself on the side of the road in the middle of nowhere with a bad bearing, that 100 bucks will start to seem really cheap in an awful big hurry.

Wingeezer · 08-21-2012, 06:33 AM

Well, I've been feeling a bit guilty about putting that outer bearing back in even though the marks/discoloration are very minor and so I think you guys have convinced me to put in a new one!

We are going away for a trip next month and normally bring the trailer to our home the day before so it shouldn't take more than an hour or so to swap it out.

Better safe than sorry I guess - and as pointed out a whole lot easier in my drive with all the tools at hand than on the side of the interstate!

I think I probably knew this all along but was being lazy!

Brian

Bill M. · 08-21-2012, 08:12 AM

Yeah, I would have replaced the bearing. Probably a good idea still. When I bought my last set at NAPA the outer race came in a separate package. The ones I bought were made in Mexico. I figured that was as good as I was going to get. They also had some made in China. I always replace the race with the bearing. I do not carry a spare. Maybe I should. But the bearing failures I have seen also have done major damage to something else also, either the hub and/or the spindle. Probably carring a spare hub and bearing would be better.

mimiandrews · 08-21-2012, 11:12 AM

Anyone found good brand bearings? Koyo, Timken or FAG bearings?

Yes!

I found Timken bearings in the correct size at Purvis Industries here in Ft. Worth. The numbers were the same as the Chinese bearings that came with my new wheels. I agree completely on the quality issues with those.

Bill M. · 08-21-2012, 11:14 AM

where were the Timken made?

mimiandrews · 08-21-2012, 11:17 AM

Usa!

MrBeast · 08-21-2012, 01:58 PM

While we are on the subject of bearings I figured this would be something noteworthy to throw out here.

MicroBlue has a coating that on bearings and engine internals drastically reduces friction and increases lifespans. A bi-product of this is increased fuel mileage. I am seriously considering doing this to my truck.

There are several truckers running them now, and just by changing out the bearings some of them are seeing 4mpg increases in their trucks. It is pretty neat stuff.

dwightdi · 08-27-2012, 03:26 AM

Since our wheel bearings roll rather than slide, I would think Microblue would have no advantage in reducing friction.

Gene · 08-27-2012, 10:50 AM

Quote:

Originally Posted by dwightdi

Since our wheel bearings roll rather than slide, I would think Microblue would have no advantage in reducing friction.

Rolling over another surface results in friction. Whether that friction is enough to justify Microblue over the usual wheel bearing grease is the question.

A 4 mpg increase is an enormous percentage increase for a large truck and would mean to mean that wheel bearings with standard grease account for enormous amounts of friction. I find that hard to believe.

Gene

Bill M. · 08-27-2012, 12:01 PM

Looking at the link provided, it says 4/10 (0.4%) of a percent increase in mpg for the best case. I would find that hard to measure, but maybe a over the road trucker has that kind of accuracy with all the miles of data.

**DKB_SATX** · 08-27-2012, 12:18 PM

0.4% improvement seems believable, though perhaps difficult to prove... 4 mpg in an HD pickup seems unlikely, and 4 mpg in a semi rig would probably represent an increase of 50% or better which isn't believable at all. Searching around I found some apocryphal comments about improvements but nothing about repeatable tests, but I confess I didn't put a lot of time into the search.

A big fraction of energy at highway speeds goes to battling aerodynamic drag, and I think rolling resistance of tires is a bigger factor than that of bearings (assuming decent quality undamaged bearings that are properly lubricated, of course.)

dwightdi · 08-27-2012, 12:22 PM

The grease provides some heat transfer as well as lubrication for the end of the rollers that are sliding over the cages. Rolling friction on tapered roller bearings is an order of magnitude less that sliding friction in a grease lubricated sleeve bearing. I doubt you can measure gas mileage that accurately, given the great variability in road/weather conditions as well as other variables. I would think Microblue would be more effective in a sliding friction application under high load and marginal regular lubrication. Slick 50 says it provides some additional lubrication for engines with pressurized oil systems.