Noise in the differential

[MGB GT]

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I’ve just noticed that when I’m making a hard right or left turn there is a growling noise from the diff. I have an 89 325I with a LSD. It doesn’t have any metal to metal sound but is almost a thumping. The same sound when you are turning an all wheel drive car in a tight circle.
Any ideas?

[wodcutr]

They are notorious for making that sound. The lsd's need a special lubricant added to the regular diff oil. If you don't know the history on your diff then you should change the oil and add the lubricant so you know it has what it needs in there. I think once the diff starts to growl though it will always do it even with the right stuff!

[priapism]

Redline synthetic diff oil, or if you want to get fancy, 9 parts Redline synth and 1 part GM Dextron. Best way to extend the life of your diff.

[bostonbmw]

I had the exact same issues you are having. Groaning during sharp left or right turns, it would also make noise on exit ramps. I went to my local parts store, all they had was "Trans-X Posi Trac Limited Slip Gear Oil Additive" so that's what I got. It made the rear end COMPLETELY quiet there is zero noise now!