Wheel Bearings Questions..

Synthetyk

Synthetyk

New Member
#1
#1
So I got around to changing my mm80 predator swapped tires from the stock garbage V tread to some Power2 SUNF. After monkeying around with the harbor freight tire changer and finally getting squared away I realized my wheel bearings have to be shot. Few of them sound like rolling through sand or grit, the others don't roll at all. I ordered a cheap set from amazon but is there a easy way to mount these things so I don't end up murdering a new set? There is a hollow bar in between them, so I assume I set one and then set the bar and mash the other... not sure how you keep the bar centered in between the bearings?

Basically was throwing around the idea of a smack with a hammer laying a 2x4 or a piece of wood over the bearing and hub to center smack it. But again, not so sure I understand how to line up the hollow tube with the other side. Maybe thread the axel through for opposing side? Defeats my 2x4 theory though then. Also had a theory about a socket just about the right size as the lip of the bearing. But with as much red neck idea's I've had lately that smells like a miss hammer slam and jacked bearing.

Any tips appreciated. I was looking up some wheel bearing press tools and my jaw dropped at some of the prices.
 
J

JimN

#2
#2
Synthetyk said:
Also had a theory about a socket just about the right size as the lip of the bearing.
Click to expand...
Absent a press, that's the ticket I use. No whacking, just a tap,tap, tapping. You could just drill a hole in the center of the wood so it's just setting on the outer race. with another piece on top to whack on. I also tend to use a 2-5 lb hand sledge. I call it tapping with mass. :D
Some people like to put the bearings in the freezer for a few hours to shrink em up a hair.
Some just tap,tap, tap around the outer race. Not my prefered method.
Since you're dealing with chinese tolerances, it could go in very easy or very hard.

Centering the crush tube should be pretty easy. Get one bearing in, put the tube in start the other bearing, get real close, center the tube and finish pressing the bearing in. Even if it's a little off center when you're finished, you should be able to center it up pretty easy. (If it was cut the right length)

Also you may need to add grease to the bearings. The chinese can be a liittle skimpy with it.

You can also "rent" a bearing driver from Autozone and the like.
 
Charles S

Charles S

#3
#3
The tube between the bearings is called a crush tube, AKA: inner spacer. It contacts the inner race of the bearings to prevent ruining the bearings when the axle nut is tightened (outer spacers should also contact only the inner race). Press or drive the bearings into the wheel contacting only the outer race. Install one bearing, insert the axle through that bearing and and place the crush tube on the axle. You could use a shorter bolt, a wooden dowel, etc. instead of the axle. With the crush tube in place, press or drive the second bearing in, stop applying pressure as soon as both bearings are in contact with the crush tube. Keep an eye on the crush tube if it's a loose fit in the hub, make sure it's lined up when the second bearing is installed. An appropriately sized socket will work well or you can very carefully tap the bearing in using a soft-face hammer (remember, outer race only) working your way around the bearing. You might get away with the 2x4 idea if the inner race doesn't protrude further than the outer race.
 
DaddyJohn

DaddyJohn

Well-Known Member
#5
#5
Like JimN mentioned, you might want to add some grease, as I’ve always found new Chinese bearings to be under-greased. I use one of those razor knives with the snap-off blades to work under the seal and pry it away without damaging it, add grease, then push the seal back in place. Easy-greasy…;)
 
R

RonGdragminis

Member
#6
#6
Just make sure you only drive the outside race of the bearing when driving it in and you will be good. You don’t even need to freeze them at all. Ther only an interface fit of like .002”. Tap them in with a hammer around the outside and use a socket that doesn’t hit the shield (middle bearing cover) and you will be fine. Always clean the surfaces good with some scotch bright or scuff pad and they will tap right in.
 
Thepaetsguy

Thepaetsguy

Well-Known Member
#7
#7
One thing to add is (at least on the vintage stuff) the bearing pocket will sometimes be tapered.

And the China 5/8 bearings are a bad idea.

Good non flanged high speed wheel bearings in a tapered bearing pocket with the crush tube is the safest way to do it besides a live axle swap.
 
Charles S

Charles S

#8
#8
DaddyJohn said:
Like JimN mentioned, you might want to add some grease, as I’ve always found new Chinese bearings to be under-greased. I use one of those razor knives with the snap-off blades to work under the seal and pry it away without damaging it, add grease, then push the seal back in place. Easy-greasy…;)
Click to expand...
Wheel bearings need enough grease to coat the rollers/balls and races. Grease is distributed by the rotation of the outer race and the rollers/balls rolling between the races. Packing the bearings full can increase heat, wear and drag. Grease should fill 1/3 of the space in a wheel bearing, 1/2 max. Fully packing other bearings, such as steering head and swingarm, is fine but is not recommended for wheel bearings. If adding grease to a bearing, the grease needs to be compatible with the existing grease. If you don't know whether the two greases are compatible, all existing grease should be cleaned out of the bearing before regreasing. I know it is common practice to pack wheel bearings (and even the hub, where it serves no purpose) completely full of grease but that doesn't make it a good practice.
 
Charles S

Charles S

#9
#9
"Too much grease volume (overgreasing) in a bearing cavity will cause the rotating bearing elements to begin churning the grease, pushing it out of the way, resulting in energy loss and rising temperatures. This leads to rapid oxidation (chemical degradation) of the grease as well as an accelerated rate of oil bleed, which is a separation of the oil from the thickener.

The heat that has been generated over time along with the oil bleed eventually will cook the grease thickener into a hard, crusty build-up that can impair proper lubrication and even block new grease from reaching the core of the bearing. This can result in accelerated wear of the rolling elements and then component failure."

The Dangers of Overgreasing
 
sparkwizard

sparkwizard

#11
#11
I say go ahead and use cheap China bearings. You're not flying to the moon or driving cross country.
When you start hearing that death rattle and decide to push it home with failed bearings, you might think about a spending a couple more bucks on a set on quality bearings that already have grease in them.
Have fun and be safe.
 
SAS289

SAS289

Well-Known Member
#12
#12
sparkwizard said:
I say go ahead and use cheap China bearings. You're not flying to the moon or driving cross country.
When you start hearing that death rattle and decide to push it home with failed bearings, you might think about a spending a couple more bucks on a set on quality bearings that already have grease in them.
Have fun and be safe.
Click to expand...
Quality bearings such as?

Last bearings I used were to do both of my TAV plates. One got Timken and the other PGN. These days I'm no more confident in the Timken's than the PGN's. I did use the Timkens in the bike that has more power and ride time.
 
DaddyJohn

DaddyJohn

Well-Known Member
#14
#14
For my Chinese mini bikes, I like to use OEM equipment (inexpensive Chinese bearings), lol… Honestly, I’ve never had one fail on me, and if one did start to whine or rumble, they’re cheap and easy enough to replace again. I usually buy 10-packs to keep the price low and always have some on hand in the most common sizes.

For my vintage US stuff, on the other hand, I also use the inexpensive Chinese bearings…:p:D
 
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