Whining noise after installation of LSD

[filip00]

Hey guys, allow me to open a thread and try to resolve the issue I'm facing since I'm kinda worried and I don't dare to drive my car now

First off, the car is 15k miles, never trashed or anything. I installed an OS Giken LSD in the diff a month ago, I used the stock shims and checked backlash and preload, it was all just as it was with the factory VLSD. Tread engangement was perfect, full coverage over teeth.
Oil used is OS Giken - 80w250.

I tested it out, all was super good, no problems. Donuts, high speed, whatever.

Now, some 300 miles after installation, I noticed a whining sound coming from the diff. It's a very faint sound, occurs at about 40mph and only gets ever so slightly louder with acceleration. Up till 70mph you can barely just hear it, the music must be completely turned off. Above 90-100mph, you can hear it as it's very similar to the ECU whine that the Z has.

Now I'm quite worried as to what is going on, I don't want to screw up anything and I'm kinda scared to drive the car at all. I don't want to immediately dismantle everything and do it all over again, but it seems to me like I have no choice. What would be my best course of action? I'm thinking of ordering in advance a few shims of different widths (anyone knows the width of stock ones?) and pulling everything down, measuring backlash again, preload etc - and hoping that I can get it all in spec again and it will remove the whine. But what if it doesn't? As now it was already all in spec and good.

Thanks for the tips and your time reading this.