I know that the front wheel hub is supposedly non-rebuildable, but has anybody here ever rebuilt one?

 

I've taken apart and re-packed a brand new one. But no, never attempted to fix a broken one by rebuilding it. Just replace the entire hub.

 

Front Hub Repacking

You can also get yours rebuilt and blueprinted, because Spec Miata guys find this to be pretty much the only weak point on these cars.

 

that's a great link. nice job newb. unfortunately I am missing one of the most important tools listed. the garage :(

 

Jim Drago on the spec miata forum sells rebuilt hubs for a reasonable price, and the ones I got from him came with Redline grease in them. It's cheaper than buying OEM hubs from Mazda (which are $150 ea from a dealer, or $120 if you are signed up with Mazda Motorsports) and saves the hassle of repacking the bearings. I take a pair along as track spares.

If I was going to spend dealership kinda money I'd probably get blueprinted hubs from ART for a couple more bucks. People generally seem satisfied that they last longer than new OEM repacked hubs.