Freeze the bearings (literally)

[dtkid]

It seems that I read somewhere that it is useful to place wheel bearings in the freezer for a spell before pounding them into a front rim.

Has anyone ever tried this. Any danger that the steel becomes brittle? Does the steel actually contract to any significant degree?

I'm fixin' to replace a bunch of bearings and thought I would check with the masters before the operation.

(I did a 'search' on the issue but didn't find an answer).

[Dogma]

Lemme see here... According to Machinery's Handbook, coefficient of thermal expansion for carbon steel (should be similar to that used in bearings for this) is 8.4-15 x 10^-6 in/in/°F. So, from room temp to freezing is about 40°, worst case is about .0003"/in. If the bearing is Ø1.5", it could shrink .0005" or more. That shouldn't be too cold to be a danger to the steel, but you'll need to let it warm up again to get the proper press fit before you ride it.

[Ed Vrolijk]

Hi dtkid,
It's common practice to put your bearings in the freezer for an amount of time to make it easyer to assemble. They don't contract very much, anyway not that much that you can measure, but enough to make ik a bit easyer.
Mind you, only freeze that part of the bearing that goes into something!
Good luck with it.
Ed

[Ghostgs1]

Hi dt, I'm sure it will make them easier to press in. It is common practice where I work to freeze bearings with tight od fits and heat bearings for id fits. As for damage to the steel, you aren't going hurt anything since you will be pressing them into there fit and you are not going to get them very cold anyway, unless you use liguid nitrogen to freeze them. Ray

[Nessism]

Chilling the bearings is a viable technique.

I used to build RC planes and perform various bearing changes on the small engines used to power the aircraft. Standard process was to freeze the bearings - they would typically drop right in there after.

[PAULYBOY]

Used to be standard practice to freeze valve guides at machine shops using freon. Still is some places. Press fit bearings also apply. I even saw Coddington do the same when manufacturing custom wheels on one of the "American Hotrod" show.

[dtkid]

Thanks guys:

One more question. I'm talking about front wheel bearings on my 1980 aluminum mag GS750s and GS1100.

Should I pack the bearings (grease) before or after I place them in the freezer? Or does it matter at all?

[trippivot]

heat the wheel bearing bore in the wheel a little too. let the temp equalize before you tighten the axle up

if they are rubber sealed precision no packing required

if they are just metal caged roller yes pack them after installation

not too much grease is needed

[SPARKSS]

You've probably pressed or drift-punched the old bearings out.......press 'em back in - room temp - no problem. This particular job isn't one that requires freezing.

[salty_monk]

Maybe not if you live in Canada.... You just leave it outside right??


Just kidding

[twistedwankel]

You've probably pressed or drift-punched the old bearings out.......press 'em back in - room temp - no problem. This particular job isn't one that requires freezing.

ditto. "Press" the bearings in on the outer race only - don't hit them with a hammer. Jarring the bearings shortens their life just like too much grease.

Don't forget to put the spacer back in before you install the second bearing

[Shin-Ken 1074]

Freeze the Bearings

Just as mentioned in some of the replys there is not much of a change in the size, but it can make a difference. If your concerned about the amount of time in the freezer and you still want to shrink the bearings here is another way to consider the job:

Place the bearigs in a plastic bag that is larger than a 10 litre bucket/container

Half fill the bucket/container with crushed ice, with the bearing in the bag place the bag about half way down leaving the top of the platic bag protruding over the top edge of the bucket/container, this way you can retrive the bearing quickly and start the fit with minimum temp increase.

Fill the bucket/container with cold water over the ice without letting any water into the plastic bag.

Bearing exposure to the ice/water will depend on the air temp where the job is being done, at 30 degrees C the bearing is normally left in for 20-30 minutes.

Shin-Ken 1074