I'm installing a new ring and pinion in a 8 3/4 rear end and wanted to know if the front bearing (the small one) on the pinion shaft is pressed on.

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"You know a car is really yours when you've touched every fastener on it." -David Freiburger

Yep.

Makes setting shim depth a bit tough. Doc's trick was to hone out an old bearing so it will slide on and off, then set shims up, then press on new bearing. You can measure thickness of both bearings with a good caliper or micrometer to compensate any differences there.

Lou

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Home of Slant6-powered fun machines since 1988

Can anyone supply me with a link to a previous post on a complete setup of a rear end on an 8 3/4? Thanks

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"You know a car is really yours when you've touched every fastener on it." -David Freiburger

The main pinion bearing is an interferance fit, the smaller front bearing is a close "running fit" so you can slide the pinion out of it, once the yoke is removed... you may need to tap on on the end of the pinion a bit , depending on how long the assembly has been together.

Sounds like you are trying to install a different gear ratio?
What case type are you working with? 741, 742, 489 or ??
Are the replacement gears new or used?
DD

I'm installing new gears in a 489 case and am having trouble setting pinion depth without a pinion depth guage. I was gonna try to set it up and see how the contact pattern looked to determine if any adjustments were needed. Is this not a good way and should I just cough up the money and buy the tool?

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"You know a car is really yours when you've touched every fastener on it." -David Freiburger

Good info.
Note: some of the 489 cases placed a shim under the main bearing race (cup) and another or no shim under the main pinion bearing. This little detail has messed me up in the past.

Are you using a solid spacer or the crush sleeve with your set-up? If it uses a crush sleeve, leave it out (and the front seal) until you find the correct main pinion shim thickness.

As already noted, a cheap alturnative to the pinion depth checking tool is the "set-up bearing" that slips on and off of the pinion with-out a press. Your can "find your way" to a correct contact pattern with some "trial & error" and contact pattern reading work... best I have done using this method is getting a good pattern after 3 trial assemblies.
If you buy set-up bearing for a 489, I will buy it off of you after you are done with it.
(I have one for the 742 case but not for the 489, it's a different bearing)
DD

Where can a setup bearing be purchased?

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"You know a car is really yours when you've touched every fastener on it." -David Freiburger

mopartsdealer on ebay lists the set-up bearings every so-often.
http://myworld.ebay.com/ebaymotors/mopartsdealer/

Doctor Diff also carries them.
http://www.doctordiff.com/?page_id=50