Strained noise from LSD?

[Nue]

Not sure where this is supposed to go but here goes:

So after swapping out the stock transmission oil for the Redline MT-90, my car has started to make a strange rumbling sound that I suspect is likely from the LSD whenever the car is turning and is cold. Or perhaps it's a wheel bearing. I'm somewhat worried as I don't recall this happening before, anyone with this issue or experience?

 

[wisniaPl]

when i put mt90 shifting is smoth and i dont have any noise

 

[Nue]

Well, not as much as to shifting but the act of turning when in first gear. Shifting to me feels more or less the same; meh.

 

[RichB]

I'm getting the same phenomenon. It goes away after I drive for a few minutes. I don't really understand why this happens to some and not all.

 

[User Name]

Maybe it's the nature of the Torsen unit itself. Different app I know, but I have a Torsen diff in my Miata that makes a helluva racket compared to a friends Miata Torsen that's as quiet as an open diff. That's just my opinion, I could be wrong.

 

[Crypt0wind]

Very likely your hearing your LSD, here's my very recent experience.

I got my trans fluid changed at a oil service place. They told me it was "synthetic 75-90wt gear oil". The next day I noticed a noise (wah wah wah) from the right front wheel area when turning to the left/right at low speed.

http://www.mazdas247.com/forum/showthread.php?t=123714556

2 weeks pass and the noise doesn't seem to get any worse or better. Monday I dropped it off at the Mazda dealer, still thinking it was a wheel bearing or CV...

Well it turns out the trans fluid was wrong. The tech drained some for me to see, it was a dark red/brown color and seemed much lighter weight. He showed me the 75-90wt Mazda would use and it was light golden. Color doesn't mean much I discover, but the type and weight does.

Mazda drained and refilled the trans with the correct 75-90wt and adds some friction modifier. The noise if gone and shifting is smooth. The transmission's long-term outlook is still in question...

 

[amascio]

I got tired of the cold weather grinding my Speed had on the 1-2 shift so I went with straight Redline MTL which is a 70/80 GL4 rated oil.

Shifting is a breeze now and so far no ill effects; noise, grinding or otherwise. Been in the box for 12k miles.

Of course, I may be greeted with "silver soup" at the next oil drain - who knows? If this is indeed the case I think I'll try Amsoil's 75/90 MT GL4 stuff and see what happens. Ought to be interesting......

 

[Crypt0wind]

I got tired of the cold weather grinding my Speed had on the 1-2 shift so I went with straight Redline MTL which is a 70/80 GL4 rated oil.

Shifting is a breeze now and so far no ill effects; noise, grinding or otherwise. Been in the box for 12k miles.

The noise I think he original described was the LSD making the noise, and not grinding gears. Mine didn't grind at all with the wrong 75-90wt gear oil. It was when you turn your wheel hard to one side at low speed. Then you get the low (wah wah wah) sound.

It seems more people have this type of problem after changing improper trans fluid... DIY trans fluid changers beware.

 

[Nue]

Was beginning to think this place was dead =P. Thanks for all the responses, but the last post basically sums up what I and others have been experiencing. Still no answer to what's causing the "wah wah wah" sound though. Crypt0wind's response has me wondering though as I did get a fairly specific brand of oil (MT-90, "synthetic 75-90wt gear oil") and I had my personal mechanic do it for me. Everything else was basically followed to the tee from instructions posted online about our cars. Seems fairly odd to me if I'm the only one with this problem if everyone else had done this already...