There have been a lot of wheel bearing failure threads this past year. I suspect the majority of problems are not with the bearings themselves, but the grease, or lack thereof. I haven't had any bearing failures on my motorcycles, but might have if I hadn't popped the seals and checked inside before using them.

Many are packed well, but some have very little grease; I've seen several that had what looked like a "string" of clear grease? (looked like Vaseline) only about 1/16" thick on one side of the bearing race. The bearing would have had to spin up before any lube reached the *****, too. I wipe anything clear off and use a major name synthetic, like Shell or Mobile, and plenty of it. It's not just motorcycles, found the same for a variety of vehicles. I've even found a few with no grease at all, even on bearings meant for jet airliners, which you'd think would have the most stringent standards of all.

Just today a member posted that he pulled bad wheel bearings from an Ultra, and it had that clear stuff. OEM, came with the bike new.

Some bearings (even Timken!) come from the factory with a preservative coating, but NO grease. That's deliberate; the user or reseller is supposed to use a grease appropriate for the application. Some of the companies that package a bearing made elsewhere, like All *****, seem to do a good job with grease, but I wonder if some of these el cheapo repackaged bearings only have preservative. Another good reason to check, though I haven't heard of any Timken wheel bearings shipped without grease.

Wheel bearings aren't really high rpm in the bearing world. A 21" wheel/tire spins the bearing close to 1000 rpm at 60 mph; just about any wheel bearing is rated at several times that speed. Wipe the grease off the outer side of the bearing after grease packing before pressing the seal back on, and this should leave enough space for a ball "tunnel" to avoid heat buildup from ***** churning through a solid layer of grease. At 10,000 rpm, this could be critical, but at street wheel bearing speeds, they handle plenty of grease. Tapered wheel bearings in cars, motorcycles, and aircraft have been packed solid since the beginning. I'm sure a lot of us old timers have done that plenty of times.

Greases to avoid using:
Moly, the black stuff. It's long fibered clay based, oil seeps out, and best for sliding surfaces, not ball bearings.

Hydroscopic grease. That means it absorbs water. Mobil 28 (it's red) is one of these. I've seen this special purpose grease used wrong, it isn't pretty, rusty ***** surrounded by grease.

Timken has some good info on grease, what to use, how to use, and what happens when you don't do it right. Pages -

http://www.timken.com/EN-US/products...ages/info.aspx

http://www.timken.com/EN-US/products...Pages/faq.aspx

I really think the Harley community (including dealers) would experience far less bearing problems by just insuring the bearings they use are properly lubricated.

Pulling the wheels on my used bikes for new tires and checking bearings is usually right up there with changing the oil when I get one, and I've found several bad bearings - but not on my older Harleys. I've pulled some metrics with under 10,000 miles that were real dirty inside. ??? Have seals like all the rest, don't know why that would be. Power washing maybe?

Plenty of threads on how and with what to change wheel bearings (I use a Pit Posse puller set), but if you have someone else do it, might not hurt to ask them to check the new bearings or let you look at them. You're riding on them, not the mechanic, after all.

Another thing I've run into is plastic ball cages, the part that keeps the ***** spaced in the bearing. I got a replacement aftermarket wheel a couple years ago that came with bearings - with plastic cages. In the trash... Imagine the pressures in bearings with over 1000 lbs of bike and people on them. I don't think any engineer could convince me plastic is as good as steel in there.

I'm sure some of you won't agree with me, have seen actually seen comments on the forum that sealed bearings don't need to be looked at, but maybe this will give you something to think about.

 

Good info there...

Something to consider...

When you pry the seal back to inspect, do it on the seal that will be toward the inside when it is installed, in case the seal gets damaged.

Many OEM metric bike bearings only have a seal on the outer side of the bearing, and the grease stays in the bearing just fine...

And remember, those bearings cannot be reused, the removal process damages them (just like every other ball bearing on an HD).

 

Thanks for the reminder, I forgot to mention that. Also, some cageless ball bearings have a small semi circle cutout on one side of a race for ball assembly, and even with a plastic seal, will let water in. The cutout side should face in from the outside, if possible, but I haven't seen any like that used as a motorcycle wheel bearing.