Rear Wheel Bearings & Axle Lubrication

The axle could be lubricated to minimize rust and ensure it will not sieze in the bearings/spacer, but the inner bearings and spacer do not move, the axle does not need to be lubricated to function properly.

I decided to 'zerk' my rear hub a few weeks ago when I changed bearings, it seems to work great with the excess grease just sneaking by the seals. It worked so good that I decided to zerk the front wheel hub, the grease actually popped the seal off on the non odometer side which was not good, not worth the hassle to zerk between rides on the front hub but when I pull it apart to grease it I can be assured that the bearings are full of grease... the zerk really works well for that.

Anyone have success 'zerking' the front hub?

The inner portion of the bearing should turn, that is if it is not shot, I've incuded a pic,


My bike has sealed bearings, so I wouldn't think adding zirks would help out much ??

If you can't rotate the bearings by hand, they're shot (imo). There's a whole lot more force applied with the wheel than with your finger! Still, if your finger won't do the trick, they're too stuck.

You might try cleaning and repacking them. The seal can be snicked out using a mechanic's scribe on the inside diameter of the seal. Take out the snap ring (on the snap ring side) to get to that bearing.

Clean 'em with a decent solvent (crc brakcleen works great). Repack by hand. A syringe from your local grange/feed store helps. You will likely still feel a 'tick' when you're done..and that's not a good thing, but it's better than not turning at all!

At something like $5 ea, just replace 'em! If you go to the trouble of taking the old ones out to service them, just put in new ones!

Or..you can get a 'lifetime guaranteed' bearing set with seals from CBR. More $$, better bearings.

Zerks won't do any good with a double sealed bearing. The oem bearings have the inner seal off. There's some debate on the idea of whether that's a good idea or not.

More folk on the side of 'use both-sides-sealed' than not.

With the inner seal out, and the zerk applying grease from the inside, you need to push all the junk out before you're accomplishing much good. That will compromise the bearing seal..but if keep on top of it, that won't matter a whole lot I'd guess.

I removed both of the bearing seals (aftermarket) before zerking, it's hard to believe how well it works on the rear hub.

The front hub is another matter, I ended up putting the outer bearing seals back on after realizing the oil seal (LHS) on the axle would get pressed out each time I greased it.

The rear hub is a pretty big hole. Your zerk applies grease from the inside out, I presume?

What's keeping it from getting past the spacer and trying to fill up the hub?

The hub is the first thing it fills up, then the bearings :) Kind of like the steering tube with a spacer to limit the space around the center tube.

If the grease gets past the spacer it will grease the axle bolt, not what I was looking for but more beneficial than a dry bolt.

I thought about this for a while and decided to try it, worst case is that I end up putting a small plug where the zerk lives now.

Houndog: I also zerked the rear hub and found it works great! Something reassuring about seeing all that grease coming out and KNOWING dirt doesn't get in. I did this when I had it apart to replace the bearings. They were cheaper without the seals too(which are not necessary IMO and the inside one would be detrimental to grease getting through). As far as grease filling up the hub goes...of all my bike expenses, grease is the cheapest.
I also zerked the s-arm bearings and it too works great.
PAUL 6585: I also had trouble turning my bearings by hand, they turned but I could feel roughness. Get yourself new bearings and you will see the difference immediately. Also if you decide to keep and service them, you'll have to do it in the hub 'cause you'll destroy 'em anyway hammering them out. Good luck,
DVO

Last time I heard that question was from a brit! That was funny. 'They' call 'em nubbins or somesuch.......

A 'zerk' is a grease fitting. 'Zerking' being a made up word, a verb that would mean 'to zerk' or to install grease fittings.

Grease nipples (we colonialists call 'em zerks) are generally inserted into a tapped (threaded) hole. Some press-fit in. Don't use those.

The fitting must be placed to allow applied grease access to the bearing, and an egress point for the displaced (old) grease. Hand operated grease guns put out huge pressures, !thousands! of pounds-per-inch (psi). Still, the grease will always follow the path of least resistance.

That's why the hub will fill up first. All of the quart+ of volume there is...to the tune of pounds of (unsprung) weight.

...but that's another issue.

Sorry CC, but I have to disagree...POUNDS of unsprung weight? I haven't CC'd it (no pun intended) but I really don't think so, even it were empty. Subtract for the axle and the bearings and there's really not that much of a void. I'll get the raz for this, but with some very quick calculations (based on my buddy's recollection of how to calculate the area of a circle), I'll go out on limb and guess at 6 oz. I KNOW it can be filled with a half empty grease cartridge.
If I was a professional racer, Maybe I'd notice some drag from the complete lubrication, or maybe the couple of ounces of weight, but I'd guess that almost no-one else could tell the difference.
If I'm wrong, I'd like to hear why?
Have a good one.

You're likely correct.

It looked like a pretty big hole to me last time I had the bearings out.

I didn't calculate or measure the volume.

If I was worried about unsprung weight, guess I wouldn't have a steel kickstand hanging on my swingarm, 'eh? ;)