Motorcycle wheel bearing installation

[NOTEVIL81]

I have no idea how many bearings you install in motorcycle wheels in your shop. But please don't over simplify this as something simple. No one in my shop is going to pound.A bearing into a two thousand four thousand dollar wheel. Some of these lightweight wheels are as thin as 4 to6 millimeters. On the outside of the bearing hub. You can watch the pressure on the press. I do not agree with heating the hub due to I do not know the composite of the aluminum. Nor do I have a degree in metallurgy. But freezing the bearing allows it to be installed with as little as 200 pounds per square inch. Same wheel, without freezing the bearing will sometimes exceed over a thousand pounds per square inch. These expensive wheels are very.
Common in southern california.

 

[Bonz]

Experience beats conjecture each time...

 

[Dborch41]

Again, with respect, saying heating leads to bad things and yet some manufacturers recommended it, I don't know where that knowledge is coming from. BMW bearings or Kawasaki bearings or Jeep bearings and hub tolerances across the board are similar, there's no rocket science in them.

Freezing is self evident, there is nothing in or about a sealed bearing that introduces any moisture worth mentioning in the negative sense. If the moisture gets in there in the first place as water (as you said) when the bike is run the first time moisture will evaporate off as a gas. In case that science is not evident here, gas will fit through a much smaller space than water. Help me understand how moisture gets into a bearing and causes an issue?

Also, what happens if the bike lives up north? The first cold winter night will freeze that bearing solid, I don't see much difference.

My understanding is that freezing the bearing prior to installation isn't to "shrink" it for an easier fit, any actual reduction in diameter is minimal at best especially with smaller bearings. The only way to get any significant shrinkage is by using dry ice or liquid nitrogen, the average home freezer won't cut it. Supposedly the real purpose is to prevent potential damage should the part receiving the bearing be heated up a but too much. Most of the excess heat will dissipate while thawing out the bearing, thus protecting the rubber shielding. I know bearings are meant to withstand high temperatures. but a propane torch can get an aluminum hub very hot rather quickly.

I'm not 100% certain on this, but I've heard about the theory more than once.

 

[Bonz]

I can speak from experience,and live in Colorado where it is -20 deg f at times during winter. Who the heck rides in those temps??? With the minuscule amount of moisture that might enter the bearing it's not gonna freeze solid and expand to cause any issue because the bearing grease will "give" as it doesn't freeze. With that said, I am open to seeing data to support the "moisture in a bearing" being purported in a motorcycle or car. It's your dime, shoot KrisZ and Dborch41.

No heartburn here, just want to understand the logic and physics behind the freezing issues that are being shared.

I've tried to "tap" bearings in as has been described and it's a rough start more times than not. Put it in the freezer until it's down to temperature, and it goes in easy. I have never had to heat the receiving end of things but it's a great idea for stubborn bearings. No bearing tolerances or wheel tolerances are the same, heating or freezing with common sense is common.

Again, the comment about water getting in the bearing from freezing versus gas escaping under the heat of use, doesn't hold "water".

If water gets in from condensation, then the first wet day in the road will let water in as well.

I am have any difficult time making the same connection from the laws of physics. If water will get in, something's wrong and gas by many magnitudes more will be able to escape.

 

[NOTEVIL81]

Great points bonz. Its absolutely shocking how much a 52mm bearing shrinks at 5 degrees.
No water migrates into the bearing in shrink rap.

 

[Bonz]

Great points bonz. Its absolutely shocking how much a 52mm bearing shrinks at 5 degrees.
No water migrates into the bearing in shrink rap.

Edited since being quoted by NOTEVIL81 to avoid minutia analysis:

Reality is, the outer bearing race is what matters. The inner race will shrink as well, so there is a net shrink of ZERO. I would like to be proven otherwise by those wiser than me as there is a lot of discussion being bantered about in regards to this that has proven to have no consequence. Outer bearing race shrinks, inner seal stays pretty much the same, inner race shrinks, no net change.

 

[NOTEVIL81]

Also, what happens if the bike lives up north? The first cold winter night will freeze that bearing solid, I don't see much difference.

My understanding is that freezing the bearing prior to installation isn't to "shrink" it for an easier fit, any actual reduction in diameter is minimal at best especially with smaller bearings. The only way to get any significant shrinkage is by using dry ice or liquid nitrogen, the average home freezer won't cut it. Supposedly the real purpose is to prevent potential damage should the part receiving the bearing be heated up a but too much. Most of the excess heat will dissipate while thawing out the bearing, thus protecting the rubber shielding. I know bearings are meant to withstand high temperatures. but a propane torch can get an aluminum hub very hot rather quickly.

I'm not 100% certain on this, but I've heard about the theory more than once.

Understanding and experience are what separate those that do this daily. Stay in your bike lane.

 

[NOTEVIL81]

Reality is, The outer bearing race is what shrinks, the seal itself is not as affected by temperatures, I would like to be proven otherwise by those wiser than me as there is a lot of discussion being bantered about in regards to this that has proven to have no consequence. Outer bearing race shrinks, inner seal stays pretty much the same, that's an even tighter clearance between the bearing seal and the race which debunks the water getting in theory.

Absolutely bonz. But I got to keep the sticky popsicles away from the bearings.

 

[Bonz]

Absolutely bonz. But I got to keep the sticky popsicles away from the bearings.

Lol...

 

[97prizm]

I always freeze the bearing and smear assembly lube on them. Later down the road with these lower quality bearings will need to be removed. Galvanic corrosion is a real thing years down the road with aluminum wheels.

Is there a way around that since so many wheels are aluminum now?

 

[NOTEVIL81]

Is there a way around that since so many wheels are aluminum now?

I believe I explained that applying assembly lube or if you wish anti seize preferably graphite (non metallic). This will mitigate dissimilar galvanic corrosion. I don't want to add any metallic particles to a press fit bearing.