Rear axle build (big ford in Cat-426 1st series) 02 outboard bearing too tight for shaft

[towbar]

Got Bower 395S bearings from dealer based on Cat part #. The other # on the bearing is 121922-0047H. The ID of this bearing in the Bower specs is 2.625" which fortunately is not true because what I measure @ 22c ambiant is 2.616". But that is no better either because the axle shaft measures exactly 2.626" also (which happens to be the bearing 'spec' ID).

The CAT manual says to heat the bearing to 135c for a hands only slip-on installation but calculated expansion in that case will give me only 0.0035" for a hot ID of still only 2.6195" which is 0.0085" short for the axle OD!

Obviously this is NOT going to just slip on, not even hot. Since the cold delta (diam. difference) is 0.012" which is 3 times the max (hight torque) interference fit clearance for nominal 2.5" diameters I have to be sure that this amount of stretch in a press is not going to damage the bearing.

Any experience/ideas/advice? TIA.

 

[HarleyHappy]

I have found, on shafts and bearings of around that size, by heating bearings and cooling shafts, depending on steel, you can expect up to .008 change. While not technical, it is just real life experience.
Think you will be fine.

 

[towbar]

I have found, on shafts and bearings of around that size, by heating bearings and cooling shafts, depending on steel, you can expect up to .008 change. While not technical, it is just real life experience.
Think you will be fine.

Thanks for that, a mechanic told me that they used to soak bearings in boiling engine oil which is close to the CAT prescribed 135c, more heat might cause loss of temper. In my freezer (-20c) I could get a shaft OD of 2.6267, or 2.6249 in a bucket of dry-ce (-80c) still being 0.0072 and 0.0054 too tight respectively. The actual measurements at 22c are shaft 2.625-2.628 and bearing 2.616-2.619.

I have .012 to get rid of. My blacksmith has a 75 ton press so I can get him to press it on but he's out on a field call today. Grade 8 bolts stretch less than standard steel and are waaaay harder than grade 9 so even before a 75 ton pres I'd need to be within the heating/cooling spread. I can't fit the axles in my freezer and a huge box of dry-ice at my address is prohibitively expensive so I need to stay with the 135c differential fit of maybe .003 under the worst case bearing ID of 2.619. That would give me +.0035 heated, just enough for a drop-on or an unheated press-on.

I'll talk to him tomorrow but it seems like reaming the bearing out to about 2.631 will be needed.

 

[towbar]

So my blacksmith just put it in the 75 ton press and done, then he said "get the puck outta here"!

Where I had used the pessimistic measures to arrive at a diff. of .012 he used the optimistic ones to arrive at .006

Still, the bearing would not slide on when I had heated it and that still makes the Cat. manual a hsitshow.