W123 - Replaced axle, differential seals. Did I do something wrong?
 

Following the various guides, I:

• Drained the differential, opened it, removed both axles.
• Replaced both differential seals.
• Sprayed out the differential with a bit of brake cleaner to get rid of the minor gunk buildup left from old fluid.
• Reinstalled one old axle, one replaced axle, remounted differential.
• Sealed up differential with Gear Oil Type RTV, followed directions.
• Filled with gear oil 24 hours after RTV set.

The differential, despite the smells-like-it-should-have-been-changed-some-time-ago oil, looked brand new. No sign of wear on the gears. With the new axle and two new seals it feels as though it is a good bit tighter than previous.

I can still turn the rotor of the jacked up vehicle and it spins the other side in the opposite direction, but it takes some force and does not move freely. There is the slightest 'feel' of the teeth interlocking softly on the new axle.

Is there a work in period? Does the lube simply need to slosh around a bit? This is the first I have ever done a job like this and I am not entirely sure what I am supposed to expect. :(

If you can turn it by the disc you should be good. The cv joints being new and tight and packed with grease are probably a bit stiff.;)

Gear oil is supposed to STINK! It has an additive that makes it smell terrible. This smell does not come from use. There is no combustion process in a gear box to cause any build up of contaminants.

I change differential oil every 100,000 miles or so, and even this might be overkill.

Well, I am somewhat relieved that being a bit stiff is normal. :)

And the stink? ...Eh, maybe so, but I feel better having changed it out.