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No no no.... Not those balls.... ball bearings! I'm replacing the ball bearings in my case and they are winning at the moment. If I get the case hotter I think they will slide in like the old ones slid out. However, I'm worried about what that much heat will do the race surfaces. So here is the question are blue balls bad?

IMG_20190104_083522 (Medium).jpg

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Yes, that discoloration indicates you heated them enough to likely remove hardening.  That said the specific alloy would dictate whether this caused actual damage or not, however my understanding of tempering steel would say they're fubar.

check out the part on tempering colors: https://en.wikipedia.org/wiki/Tempering_(metallurgy)#Normalized_steel

 

Edited by braindead0
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I'll be more conservative with the heat when installing the new ones. 

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Why has the bearing been heated? If that's just from the casing then it must be verging on melting....

The thing most guys do is chuck the bearings in the freezer for the night, then heat the cases (only to the point if you dribble a bit of spit on it it boils away-no hotter) and the bearings will drop right in.

That one is shot, chuck it away.

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Just to clarify... I'm not heating the bearing. When I removed the bad ones (the one in the photo for example) I used the BBQ and let the case get to about 450f. After pulling the new bearings from under the dry ice the main slid right in. The transmission and balancer bearings heated up and expanded before reaching the bottom. I'm just trying to figure out where the sweet spot (heat) is for getting these things in the case. As it sits the 2 of 5 are in on the right side of the case.

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I dont heat or cool nothing down you should just be able to tap in the bearings with a rubber mallet that's how I've always done it. Pluses you are risking the integrity of the metals playing with heat. Just evenly tap then in there. It does take time, have patience

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300 max for aluminum. Hopefully the casings were heated slow and there was no damage.
No dry ice on the bearings. I don't no why but it's a no no according many manufacturers.

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9 hours ago, speedtoad said:

300 max for aluminum. Hopefully the casings were heated slow and there was no damage.
No dry ice on the bearings. I don't no why but it's a no no according many manufacturers.

Dry ice will not cool the bearing evenly, shrinking from the outside in can cause actual physical damage.  Suspect it's much more likely on smaller bearings, but sounds like a good thing to avoid to me.

300 seems a bit low for aluminum, air cooled engines can run hotter than that.  Probably a good safe number though.

Edited by braindead0
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Dry ice will not cool the bearing evenly, shrinking from the outside in can cause actual physical damage.  Suspect it's much more likely on smaller bearings, but sounds like a good thing to avoid to me.
300 seems a bit low for aluminum, air cooled engines can run hotter than that.  Probably a good safe number though.
300 to 400 degrees, beyond that there isn't much to be gained.

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On January 4, 2019 at 3:54 PM, u83AAf3 said:

Just to clarify... I'm not heating the bearing. When I removed the bad ones (the one in the photo for example) I used the BBQ and let the case get to about 450f. After pulling the new bearings from under the dry ice the main slid right in. The transmission and balancer bearings heated up and expanded before reaching the bottom. I'm just trying to figure out where the sweet spot (heat) is for getting these things in the case. As it sits the 2 of 5 are in on the right side of the case.

This is just plain over kill.    Drive the old bearings out as is. None of the processes that you are using.  On install of the main bearings, heat the race for a minute or so, drop bearings in. If needed tap around outer edge to finish. The rest of bearings can be driven out and driven back in.  Do you think legit machanics go through the processes of what you are doing?  You maybe a first timer and that's all right. You'll learn that there is a better way. Good luck!

i did have a experience with hot rods bearings that when they were in contact with some heat that the steel would change color. I took that as they were cheap bearings. I always use OEM. 

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A *good* mechanic will heat the case to there is no longer a press fit - the bearing drops in.  If I remember correctly, some service manuals specify this procedure.  Pressing in/out bearings at room temp will smear/shear material from the cases.  After a few times the bearings will no longer press fit into the cases at all!

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11 minutes ago, bikedude987 said:

A *good* mechanic will heat the case to there is no longer a press fit - the bearing drops in.  If I remember correctly, some service manuals specify this procedure.  Pressing in/out bearings at room temp will smear/shear material from the cases.  After a few times the bearings will no longer press fit into the cases at all!

And in cases when pressing is appropriate, a 'good mechanic' has a press and the appropriate dies/tools to press fit bearings.  Most regular garage folks don't have all of that equipment and heating/cooling of parts is a very reasonable workaround when done properly.

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20 hours ago, speedtoad said:

300 max for aluminum. Hopefully the casings were heated slow and there was no damage.
No dry ice on the bearings. I don't no why but it's a no no according many manufacturers.

Over 300c deg affects the aging of the ally. Not good for strength.

Timkin say don't let the bearing race go over 265c deg.

Dry ice is too cold, around -70-80c if I remember correctly. Similar issue to heating things too much. Timken say use a 1/2  dry ice and half antifreeze mix and an accurate thermometer -65c max

Using Timkin as an example (their worksheets), I'm guessing other half decent bearing manufacturers will recommend similar.

 

Edited by DEATH_INC.
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