I have a 99 Bonneville and my driverside front wheel bearing is going bad. I plan to replace the hub soon but wondering is it necesary to replace both front hubs as preventative maintenance? Also, does anyone know what size the large hub nut is? (30mm-35mm)? will a SAE size work in place of a metric?

This should help you out. https://www.gmforum.com/mechanical-134/wheel-hub-replacement-290447/

And no, you don't need to change both unless you want to.

Thanks for your response Dan. Those pics will help alot. Do you you by chance know the torq specs for the hub bolts both large and small? I have seen conflicting torq specs so I'm looking for a third set of specs. One said 65 ft lbs for the 3 small hub bolts and 75 ft lbs for the 1 large hub nut. The other said 90 ft lbs for the 3 smalls and 150 ft lbs for the large nut. Any advise?

Front hub/bearing to knuckle...........70

Hub nut (91-99)........................108

Good info guys! Never thought using a bolt and nut to push the bearing out, I'll have to try that one! I always just use an air hammer at work and rotate the hub inside the spindle to break them free but you do get some stubborn ones! The Pontiac Torrent and Chevy Equinox are HORRIBLE for seizing in. I'll try that bolt and nut trick on the next tight one I get!

I've never had it not work. I guess if it'* really stuck, you can use fine thread, one on each side, crank them tight until it pops.