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?

I haven't changed mine out but every other German vehicle I've worked on has little gaps in the backside of the hubs behind the races - I take my punch and walk them out. My set of race install tools weren't that expensive either but then I was making my living with them so the expense was negligible. Before I bought them though, I'd take the old races and stack them on the new ones and gently tap them into place.
I'd think your idea of dry ice or just putting them in the freezer for hours will work fine.

I have just driven the old ones out like mqp4591 explained above.
The new ones I drive in at room temp with the harbor freight aluminum bearing driver tool and a BFH.

I have even driven out a new set of bearings and driven them back in (wrong rotors on first attempt) and they seem to be holding up fine, but my car is not a high mileage vehicle.

Oven and freezer work great but you have to use a race driver or else it's very difficult to drive them square. And if it takes you more than few seconds to drive them in then the temp of the race will match the temp of the rotor and you lose that advantage.

Been awhile since i have done 914 wheel bearings, but last couple of cars I've done I bought the cheap Harbor Freight driver kit for races. Worked great.

Race in freezer (hour?), used a heat gun laying on ground pointing towards hub area for a few minutes

Nothing beats getting them in smoothly than a little grease and use a threaded rod and nut / race adapter to pull them in slowly and straight . . the trick is starting them straight and flush before starting so there is no galling which occurs when they race walls are not parallel to the hub walls. Once you get a gouge and chip started it only gets worse.

Or the correct O.D. Harbor Freight impact socket and a hammer. And Dave said it. Start square. You can hear and feel if it is square by the sound of the hammer striking.

I found there was a tool in the collection I bought. The oven heat to 250 on the hubs and freezer on the bearing races made no difference. I pulled them in with the tool using the complete bearing and had them done quickly.
Thanks to all who replied.

I just purchased new rotors and bearings from PMB, so I will be attempting this as well. My local O'Reillys has a "bearing race and seal driver set" as part of their tool loaner program.

http://www.oreillyauto.com/site/c/RentalTo...ord=tool+rental

It is shown in the first column third row. Is what I should use?

Ray

Did the 911 with hub on the stovetop and race in the freezer, used old race to hammer in new race flush. Been doing it that way my whole life, never failed

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.

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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For the rear bearings I found that you have to freeze the bearing overnight to be effective. I also had success with dry ice/ rubbing alcohol bath.

To get proper size driver I take the old race and my bench grinder, I spin the race as I grind the OD. In a few minutes you have a slightly undersize driver that works perfectly.
I have a whole collection of them.