Installing bearing races in front hubs with dry ice or heat, Anyone try it? Options

[bdstone914]

I have always found these to be a PITA to install. I have tried installing the rear bearings after freezing them and cant see any difference.
If expansion and contraction are proportional to the temperature then dry ice at -109 F should make a big difference. Used in combination of putting the 911 front hub in the oven at 250-300 degrees I am hoping the races will drop right in.
Anyone tried it or have an easy method without the proper too size puller tools?

[veekry9]

https://www.google.ca/search?q=induction+he...UTqATAQ_AUIBigB
https://www.google.ca/search?q=high+speed+s...eating+oil+bath

Check the temperature of your shaft and bearings,calculate size at standard ambient.
Check your clearance by measuring,write it down,calculate the interference dimension.
Heat the female and cool the male.Insert.
(IMG:style_emoticons/default/happy11.gif)
https://www.google.ca/search?q=high+speed+s...RY6ALwQ_AUIBigB
https://www.google.ca/search?q=high+speed+s...+spindle+design
https://www.google.ca/search?q=high+speed+s...=shaft+bearings


https://www.youtube.com/watch?v=LVODJm05plw

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https://www.google.ca/webhp?sourceid=chrome...bearing+fitting
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04-24-2006, 10:16 PM
Forrest Addy
Bremerton WA USA

"Freezing a bushing to -78F(Co2) or even - 320F(N2) gives you a limited amount of shrink. Compounding the difficulty of assembly is the cold bushing accumulates iron hard ice from the humidity in the moment it emerges into the ambient air from the dry-ice, lN2 whatever have gurgling away in the coffee can. The ice accumulation begins the instant the bushing is exposed to air and continues until the ice melts. It takes only a few seconds.

As soon as the bushing makes contact with the warm bore the hard ice may prevent assembly. The ice soons melt and in doing so pumps a lot of heat into the formerly cold bushing. This is a bushing with a thin wall. It has very low thermal mass and a lot of area. Unless the thermal equilibrium interference is small, forcing the bushing into place with rough expedients may result in buckling it. Better make a bushing driver just in case.

If you can heat the mating part to 300 degrees you get that much more assembly clearance and a chance for a slip-in-place assembly. An hour with a 30K BTU IR heater focused on the spot will heat the bore gently.

Calculate your shrink allowance and assembly interference carefully. Success or failure depends on shop arithmetic and a knowledge of coefficients of thermal expansion."

http://www.practicalmachinist.com/vb/gener...rink-fit-89092/
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