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Discussion Starter #1
Last year I replaced all the seals and bushings when I dropped my diff to replace a leaking input shaft seal. Huge PITA, but learned a lot.

I was meticulous about the job, did tons of research, made sure everything fit back in place cleanly.

Wondering though if another blown input seal[0] was the result of something inside of the diff that was vibrating, causing this damage? Or maybe I just got sloppy?

Is there a bearing in there that I missed? I looked at the exploded view of the diff in TIS[1], but it doesn't show anything inside of the diff, and I don't remember when I had it out, if there was also a bearing in there. There has to be, right? Could the bearing be spun, causing vibration, leading to this seal being compromised? Maybe I just got slippy and didn't set the seal properly. TIS doesn't show any of the internals, but there are pinion and ring sets for sale out there, which leads me to believe that there's other parts I should have paid more attention to, while doing this.

Drinking a beer in the garage figuring out a plan but in the mean time, just wanted to see if anyone had any.... "input".... on this.

Thanks!
-dant




[0] RealOEM.com - Part Search
[1] RealOEM.com - Online BMW Parts Catalog
 

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Discussion Starter #2
Also, note that last year I also replaced the prop bearing (the one on the transmission end) and the flex disc. I haven't noticed any vibrations anywhere; in fact everything immediately felt wonderfully tight, and that's continued to be the case since the work.
 

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Hmmm. I'd do two things. First, I'd put a dial caliper on the input to the rear diff and measure if it turns out of round. Second, I'd probably have the entire driveshaft balanced. I believe that they are balanced as full unit, including the input flange on the rear diff.
 

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Discussion Starter #5
Ahh, that's a great idea. I'll throw a dial indicator on it and see if it's off. As part of the previous work I did split the driveshaft to put in a new centering sleeve. I was meticulously careful about putting it back together because I was paranoid about maintaining the balance. I even stamped the input flange and the DS to mate them together in the right spot, but who knows, maybe I was off by a tooth or two? I'll drop the whole line and take it to get balanced.

Good stuff, thank you.
 

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Discussion Starter #7
No, I don't believe that to be the case. As part of the work last year, all three were replaced. Being that they were totally shot, I got a good feel for what it's like when they're blown. Whevetever may be causing this is too insignificant to cause a noticable vibration but I'm still betting something is off enough to blow that seal.
 

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The factory seal is EPDM which is not the best for oil service. You could get an aftermarket Nitrile seal for 1/4 the cost and give it a try? With all of the bearings on a fix trans and diff it is doubtful that it would be a problem.
 

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Discussion Starter #9
Revisiting this, sorry for the delay.

Got all my parts in anticipating just to replace the seal but there's some highly suspect gunk stuck to the magnetic diff drain plug. It's very fine, not sheared, but definitely ferrous.

I'm thinking one or more of the diff bearings are blown.

If the pinion bearing is to blame here, that would have ill effects more than what I suspected the transmission and engine mounts to cause, right?

Looks like they sell aftermarket bearing replacement kits. Easy enough, break old ones out and press new ones in. But i'm worried about the crush sleeve and setting the proper load on it. I don't think I'm equipped for that, unless there's an intuitive way of setting it?

I found a nice list[0] of E39 bearings and a crush sleeve (suggested to get two, in case you mangle it on the first try), but I'm not finding such a list for the E60. I know these are internal parts not meant for outside of dealer service but, it is what it is. Trying to prepare for next steps if these bearings are in fact to blame.

Thanks!
-dant



[0] DIY: - A differential story, pics inside
 

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The crush seal is not terrible. The hardest part is getting a bar long enough to crush the sleeve. There will be a spec for backlash that can be measured with a dial indicator. My guess would be .006-.008". As far as the bearings go you will hear them long before they fail. The downside is you may chew up your gears that way.
 

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Discussion Starter #11
Ahh see, even then, it would be guessing at best :)

I'm going to take it in and have the pros go over it. If I don't do that, I'll always be second-guessing the work I did or worse, it would just blow up.

It's been fun learning about diffs, though!
 
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