I attempted to start a similar rear wheel bearing job a few days ago on my W210 (same as most 124's) and it didn't go very well. After removing the 30mm outer nut from the axle shaft, the shaft will not move inward. It appears the splines of the axle shaft may be rusted together with the splines of the hub. Soaked it in Kroil for an hour or so, beat it with a sledgehammer, tried a torch on the hub, so far it won't budge a single millimeter.
Added more Kroil, more BlueWrench™, and pounded on the end of the axle more with the sledge. All that did was start to mushroom the end of the axle shaft, which isn't good. Of course, I do not have the fancy $1200 factory tool for pressing the shaft out of the hub. I then tried a 3-jaw puller (photo attached), which pressed on the axle end similar to the factory tool, but that didn't move it either.
Soaked in Kroil overnight, attached a different/stronger hub puller, and hit it with the impact wrench to press the axle shaft out. I chickened out and backed off the impact wrench before the tool broke or threads stripped. Next I removed the tool and tried heating the hub for 6 minutes straight via Bernz-O-Matic until stuff started to smoke, and slammed directly on the end of the axle shaft with a sledgehammer. And...
It. Would. Not. Move. The damned axle appears to be welded to the hub. I gave up, and put it all back together so I can get the car off the lift. All my hammering has probably damaged the bearing even worse than it already was. But wait, there's more! When I got done putting everything back together, the wheel would not go on. Like, not at all. Turns out when I was bashing on the axle end with the sledgehammer, a couple times I missed and got the edge of the hub, which also centers the wheel. There was no visible damage, but it was out of round enough to prevent the wheel from going on. An hour later, after hand filing around the perimeter, I was finally able to get the wheel to slide on normally. I bet there will be more surprises when I test drive it tomorrow.
Anyway, I bought a used knuckle assembly and axle shaft from a salvage yard. I'll have to replace both the axle and the entire hub/knuckle assembly since I can't get the old ones apart. On the bright side, I probably wasted a good 6-8 hours including two trips to the hardware store for bolts, and research time on the EPC and eBay to find the correct donor parts. Now I gotta hope the used stuff I get is correct, and isn't junk. Should have both delivered next week for $105 total.
Related anecdote: The FAG brand bearing was made in Slovakia, and came with a "Ruville Germany" hardware kit... made in
Taiwan. Photos of the FAG bearing kit are located at
this link, they are too large to upload to the forum. Further adding to my opinion of Taiwan parts, the outer 12-pt axle nut included with the kit is not the standard 30mm like factory, it is 2mm larger, and does not fit on the axle shaft. I keep factory nuts in stock so it wasn't an issue, but c'mon, seriously? I know, I know, what do I expect for $46... if I ever do this on a 500E, I'll probably shell out for the OE bearing kit at triple the price.
Bottom Gear Top Tip: The
first part of this job should be to remove the 30mm axle nut, and confirm the axle shaft will move inward, BEFORE you tear everything else apart. Oh, and as SMP found out the hard way, a healthy 1/2" impact wrench is the way to go for removing the 30mm nut... spins it right off with zero effort.
I hate working on cars.