Bearings popping out of cases after installation? Wtf.

[TwiceDead]

Hey guys,

I've been a heavy equipment mechanic for a while,  I've rebuilt transmissions and differentials more expensive than most cars. 

So I figured installing bearings in my crankcases would be easy, but something strange is happening.  I froze the bearings over night   I heated the crankcase in the oven.  I popped the bearings in place and gave them a couple taps with a bearing driver set to seat them.  I tap in the water pump bearings and governor bearings and the 6905z shift drum bearing falls out.  I notice the input shaft bearing has started to work its way out. 

Very Weird.  I know these bearings are not in there super tight and have retainers.  Anyone see this before?

[alward25]

Your case is still hot when the bearings start to warm to room temp and sweats condensation.  The water evaps and pops out the bearings.  I don't like to freeze stuff for this very reason. It also induces condensation into my engine.  Also, the trapped water could cause the bearing to rust between the outer race and the bearing bore.  I may heat the cover a little and use a little oil and light press or careful tap.  Freezing bearings has become all the rage.  The bikes are not the tight of tolerances, sorry to say.  We are also going away from it on helicopters for the same reasons I listed above, which are tighter tolerances.  Just my dos centavos

Alex

[TwiceDead]

I was thinking condensation also, but never seen it before haha.

This is the way I've ever been doing it lolol.  So strange to see this happen,  I literally froze when I saw the bearing fall out,  I was like wTF wtf wtf.  I've never had this happen and I've been using dry ice, fire extinguisher, propane etc to freeze bearings.

Anyways after wards I tapped them back in, and gave them a lube with some 10w40.

[81cr450]

Never used any thing else, a chisel between the crank webs , just lightly stuffed in , is plenty to keep the crank true. Use care to start the bearings 1/16 or so , lift off the pressure to let it square up before seating. I don't use oil though bearing , retaining compound, go light & work fast

[alward25]

 "I literally froze when I saw the bearing fall out,  I was like wTF wtf wtf. "