I think I keep toasting diffs

[b*saint]

So last summer I noticed the passenger side bearing was wet on my diff. It never went that low I kept the level high. But I was getting a whirring grinding noise at speed and since I wanted an LSD I swapped in another. The old one def had a bad bearing. The output shafts clicked as you spun them. The new one (bought with 145k on it) has been quiet but now that I have about 5k miles on it, its making a similar sound and leaking again on the right hand output flange.

Some background:
This is what I did. e36/5 (essentially an e30) small diff with 318ti stock axles. The axles and diff were toast.

Swapped in an e30 medium diff with e30 axles. Smooth diff before I put it in.

Do you think its maybe just coincidence they are both leaking from the same spot and when I take it down next weekend and its shot, its just a coincidence?

[e30leigh]

the diff will sound terrible if you spin it off the ground cos theres no load on the spider gears. so dont take a bit of clunking noise while the diff turns off the ground as bad. a grinding noise how ever is different.

its also very common for the side seals, even the front seal to leak with those kinds of mileages. i see diffs leaking from seals everyday. although its mostly just seeping and not a major.
if i was you id replace the seals on the new diff. if the leak is bad that last thing you want is the lsd to run dry.
also id check your wheels bearings and make sure that your tyres arent noisy as well.

[b*saint]

This is all on the ground loaded.

Its noisy with a load on it. Not in the air. Im probably gonna pull it down next week.

The clunking sounds like if you had a loaded bolt and it was being pulled through a sheet metal hole and rasping one or two threads.

[Wanganstyle]

This is all on the ground loaded.

Its noisy with a load on it. Not in the air. Im probably gonna pull it down next week.

The clunking sounds like if you had a loaded bolt and it was being pulled through a sheet metal hole and rasping one or two threads.

if you had a 1995 e36M3 I would suspect the LSD button head 6mm allen bolts backing out and breaking, the heads often fall out when people change the oil. BMW forgot loctite on those most excellent models.

if you did not replace the seals with new before install, perhaps its hating on you now? Diff bearings die, its a common occurance. People are often driving around on dying diff bearings for months without noticing it.

[b*saint]

Yea I just figured the previous seals lasted 100k miles longer. No big deal. Its nothing to take a diff out.

[Wanganstyle]

the diff will sound terrible if you spin it off the ground cos theres no load on the spider gears. so dont take a bit of clunking noise while the diff turns off the ground as bad. a grinding noise how ever is different.

its also very common for the side seals, even the front seal to leak with those kinds of mileages. i see diffs leaking from seals everyday. although its mostly just seeping and not a major.l.

A diff with proper set bearings in good health will not sound terrible. no way.

The clunking you hear when you spin a random old diff on the shelf is the backlash between the gears, the wear over time = play. engaging the imput shaft will cause the ring and pinion to engage and move the outputs; this engagement is the clickyclack you hear. Also called "Backlash"