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.

2011 Nismo#91

All diff's make noise, some more then others. Mine a Quaife has a noticeable whine at just highway speeds. How you describe it I think it's perfectly fine.

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filip00

Thanks for the input, it is a bit comforting to know that. I must say though, That just changing the LSD "inside/below" the final drive ring gear, I would expect that *nothing* should change. I do understand difference in noise when the LSD is engaging, but in regular driving on the straight road I would expect it should have to be exactly the same as it was, no noise. This is why I'm so worried in the first place.

Averying

What kind of break in procedure and break in oil lifespan is called for? Did you follow that?


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filip00

No break in procedure is defined. I did nothing special, drove the car as usual, with a few donuts engaging the LSD fully. Oil used is the one per spec, but I was planning to change it after 500 or so miles, so sometime soon....

Rusty

Drive it for 500 miles before you beat on it. Change lube at 500 miles and again at 1,500 miles. My OS Giken has a slight whine to it too.

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Spooler

WOW, mine has always been quite.

Rusty

I got hearing aids. You don't. You can't hear chit to begin with.

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filip00

What's weird about this is that the noise started to occur only recently, at around 250 miles after installation. First weeks of was super quiet. That's why it's so confusing for me

Averying

Report back after you change the oil for the first time and see if that makes a difference.


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Jhill

This is exactly why I wouldn’t install one myself. I’ve done diffs before and all that but never truly feel comfortable and check teeth profile over and over on install because you only get one shot. Once it whines that’s it the gears will not stop whining and no amount of readjust will fix it.

filip00

Well, I doubt that you can't fix it anymore, it's not like the teeth have been ground off and ruined now. I didn't trash it and whining has occurred only on the last 60-70 miles or so.

filip00

Never updated this thread so just to update it - in the beginning of winter I disassembled the LSD once again and rechecked backlash and tension etc, have flipped the spacers and I was within specs. As it was before, it seemed just a tiny bit too loose, but whatever. Now that I reassembled it, put new oil in it (the old one did about 1,5k miles), there is no more noise. Diff is silent, all good. I would say the whine was due to too much backlash, however little it was, was apparently out of spec.

Rusty

What was the backlash?

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filip00

Ah f*** me if I can remember the numbers, I did it back in november. I forget because all my measurements were in mm, and I had to recalculate all specs I found online in inches, so I have no recollection of what were the numbers. I remember though, that it was in the middle of the spec - which was a relief, because I really wasn't feeling like trying to machine-guess the new shims to fit.