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Discussion Starter #21
This maybe true for the bearings but not for the pinion/ring, as you heard the noise before with less torque on the nut.
Gotcha. I should've been more specific. In addition to the bearings, I was concerned with over-crushing the sleeve causing a teardown of the differential. From what I read and viewed if the nut was overtightened the crush sleeve would be ruined necessitating replacement.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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[

The real issue is that when you make the nut tighter, you draw the pinion shaft and gear further forward and create a different mesh pattern between the ring gear and the pinion gear. Sometimes over tightening too much can create too much driveline lash when on/off the throttle. Can also cause pinion gear whine.

If one must....... I'd say limit it to 1/8th of a turn. Marking perfectly before removal is paramount. I use a pin punch and take my time. When I'm done, the two dots line up. Paint or crayon can be wiped off unintentionally.
Not true. The pinion depth is fixed by the inner bearing and shims, so the pinion cannot be drawn forward further. If the nut was over tighten then the bearings drag torque would be very high because the pinion moved a few micrometers forward to change the gear mesh pattern.
[/QUOTE]

I think you misunderstood my intention.
Yes the general contact pattern is set by the spacer under the bearing. Generally numbered -7 to +7 (on older differentials, and yes 0 is a number/setting albeit I've not seen it with all of my differential rebuilds/refreshing.)
I was trying to point out that if you over-tighten the pinion nut, you place a hell of a lot of load into the pinion bearings. If/when one does do (by making it too tight) you do two things:
Prematurely wear out the bearings by having them too tight.
You will also draw the pinion shaft forward a little in doing so.

By a large margin-NO but it will change. This is why one uses a drag type torque meter to check what you've accomplished.
I was merely trying to point out that one shouldn't over-tighten these things w/o knowing the possible ramifications. You can see the torque meter here: # 00 2 000
(using older instructions as all of this stuff was removed from repair manuals a long time ago.)

https://www.newtis.info/tisv2/a/en/e36-316i-lim/repair-manuals/33-rear-axle-rear-wheel-drive-guide/33-12-crown-gear-pinion-with-bearings/BCkVjI6
 

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Finally got back under to inspect and correct the pinion nut. Turns out I did hit the spot right on (marked by wife's pink nail polish, lol). So left it as is.

Ended up refreshing rear diff bushings (2 in cover) with e36 M3 diff bushings and new castrol oil.


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I ended up turning the pinion nut an extra 1/2 turn past where I started. This left me with 15 inlbs of running torque.

I know a 1/2 turn is a fair amount more than an 1/8, but that seemed to be where the flange needed to be seated.
So what happened? You're now right at the original factory marking, but the nut was only turned 1/2 turns from the first trial which you stated that it was on the marking. Things are not clear.
 

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Discussion Starter #27
So what happened? You're now right at the original factory marking, but the nut was only turned 1/2 turns from the first trial which you stated that it was on the marking. Things are not clear.
I'm fairly confident I was at the right spot when I first reinstalled the input flange and nut. That feeling is based on how many turns I counted on the way off and back on. The marks were matched and there appeared to be the same amount of thread exposed on the pinion.

After the initial reinstall and subsequent test drive I noticed the whining from the differential. I did some research about the process and came to the conclusion the nut may not be tightened enough. When I disconnected the driveshaft from the input flange there was too much slop, ie not tightened enough.

I began tightening it further in extremely small increments, checking the running torque each time. When i got to approx 15 in lb I decided that was enough. That equaled approx 1/2 turn further than what I had started with (After the reinstall).

Perhaps my initial reinstall was 1 turn shy of where I started, as you suggested earlier. I was comfortable leaving it where I did because the running torque was acceptable and I knew it was tight because I couldn't get much more torque on it counterholding the flange and tightening with 1/2" drive ratchet.
 

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I'm fairly confident I was at the right spot when I first reinstalled the input flange and nut. /QUOTE]
So the nut was aligned to the marking.

I began tightening it further in extremely small increments, checking the running torque each time. When i got to approx 15 in lb I decided that was enough. That equaled approx 1/2 turn further than what I had started with (After the reinstall).
Perhaps my initial reinstall was 1 turn shy of where I started, as you suggested earlier.
Then the nut was tighten 1/2 turns more and the diff is happy. So now the nut should be 1/2 turns away from the marking and not right on it as you said. I'm confused.
 
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