Rear wheel bearing on a 10 year old car with a bit of corrosion. Maybe my biggest DIY challenge so far-- This job is no joke. We had access to a lift, air tools, impact gun, etc., and we needed all of those things in addition to fire, patience, penetrating oil, and ingenuity.
In the pic, you can see a nice shiny axle nut. When new, this thing is torqued to 150 ft. lbs. So getting it off a week after it was built was already going to require breaker bars and leverage. This nut was rusted so heavily that it was basically round, and it's only shiny here because it's been cut down by a die grinder, which was a fabrication move to make this 32mm nut into a 30mm nut so that we had 12 points to grab onto. We finally got the nut off, but 10 years of rusting together plus factory press-fitting of the hub made hub removal nightmare #2. Enter slide hammer, which was an emergency measure auto parts store tool rental (thanks AutoZone!) on 12/23 @ 7 PM. 15 mins of slide hammering and the hub is off. Now the actual bearing which is secured with four internal to the trailing arm bolts that are not only rusty, but hidden behind the axle, shock and trailing arm. Doesn't matter if they break or not, but they're large bolts so breaking them will be a challenge, so lots of extensions, some heat, finally bolts are out. Bearing removal - Once again, slide hammer with a wheel hub puller, and the bearing is out.
Next challenge - Built a press to install the new bearing on the old hub. Parts houses say use a new hub, but seems like it's going to require the same work to reuse the old hub. OK so the press is probably the easiest part of this job; straight-forward process but still sketchy as the bearing is a tough push. Patience and the bearing is seated and hub is ready to go. Finally some forward progress.
Time to install the hub back on the half shaft. What nobody tells you, and what's not in any of the how-to videos that are out there (and you don't know until you try to assemble the hub back onto the half shaft) is that the splines of half shaft don't really go into the hub without some sort of miracle. Seems like the hub may have been hot and the axle cryogenically frozen when originally built to ensure a tight fit. The general idea is to try to get enough threads on the half shaft exposed so that you can thread the new hub nut on (nut is now 36mm), and then slowly pull the shaft through the hub via tightening the nut. You can't do this unless you catch several threads with the nut, and getting the shaft this far exposed is almost impossible. I'm like, WTF, I've never seen this; if you search "E92 can't get axle in the hub", you'll see various horror stories on how bad this job is. It's that bad. Several hours later, careful heat on the hub, hammering the axle flange from the rear with a 3/8" extension while turning 90 degrees to coax it through just enough, by some miracle the axle exposes enough threads to carefully start to draw the axle through the hub with the nut. Victory is close.
Reassembly of the parking brake (the mechanism of which is another clever puzzle dreamed up by BMW's crack engineering team) complete, reassemble rear caliper carrier, put the brake back together, and it's done.