Differential Whine (Revised Factory Diff with Cooling Fins?)
 

I just purchased a 2011 370z 6MT with Sports and Touring packages, the car has 14k miles on it. I have been experiencing a whine at 50mph+ and am fairly confident it is the rear differential. The whine only occurs at higher speeds in all gears 4,5,6 and still occurs even when car is in neutral. I have searched this extensively and found there is potentially a revised factory differential with fins according to the post below, but cannot find out any other information besides what is below on page 7.....

http://www.the370z.com/diy-section-d...-change-7.html

Has anyone else had their differential replaced by the dealer with this "revised" version that has cooling fins?

I am under factory warranty til Sep 2015 and have made an appt at a dealer this week, but would like to come as prepared as possible because i am sure they will try to say this is normal or they don't hear it etc...

Thanks for any other information you guys can provide.

the diff cover with fins is a NISMO part. it is not a revised part, unless you're in dubai or other markets where extreme heat is an issue. a diff whine could be many things. if the rear diff bushing was replaced, then you'll likely hear a whine, depending on how it was installed. also, if the VLSD was swapped out with an aftermarket unit, then a whine would be more pronounced as well.

the diff cover has absolutely nothing to do with a diff whine

I'm not asking about the cover rather if there is a "revised" factory diff that nissan is using because the differential whine seems to be a common issue

As far as I know my differential is stock

usually, if someone changed the diff bushing, they install a nismo diff cover as well. kill 2 birds with 1 stone type of deal.

Vlsd is what you have stock on a sport model. They shouldn make a lot of noise. If someone upgraded the diff then those do make a reasonable amount of noise.

Is there an easy way to determine if the diff is stock?

Sounds like the same noise I get with my whiteline diff bushings.

https://lh5.googleusercontent.com/-e...0/SAM_4945.JPG

This is the pic of the "revised" differential with a new cover design that someone allegedly had replaced under warranty in CA, as you can see it is not the nismo diff cover and was replaced on a US car, just weird that I cannot find out any other information on this anywhere.


I guess i will just take it in Thursday and see what the dealer can come up with.

The car did have an intake when i purchased it but has the stock exhaust system and cats, stock suspension, no wheel spacers either. I find it odd that someone would mod the differential or install differential bushings before modding the exhaust, suspension, or adding wheel spacers.

that is not a finned diff cover. it is the finned differential housing that comes in warm weather climates such as the UAE and australia. some australian's can chime in here

I don't recognise this diff housing .... my Z34 (Japan built) has a "smooth" case - I have the finned NISMO diff-cover and I did notice an increase in NVH when I fitted it, and that got worse when I fitted Whiteline bushes - just something else to tolerate (or I just turn the muzak up a bit).

This diff housing looks a bit like the big-bertha (R230) diff in my 300ZX TT which is an amalgam of 5 different cars that my nephew is slowing building into a race-car. Best get the car on a hoist and try and find some identifying marks on the diff case itself to identify exactly what it is.

I'm not sure I like that drain plug hanging down underneath albeit that the exhaust would take a pounding before it was hit, but you never know.

Thanks for the reply's guys, I just got word back from Nissan of course they did not hear anything and they were trying to charge me a diagnostic fee which i immediately refused. They said it could be my tires which are not a warranty item... They also said they checked all the bearings, but did not explain if they checked the differential bearings so my wife is going to ask if they actually checked the differential not just the wheel bearings. Ya pretty sure tires don't make a high pitched piercing whine only at highway speeds.

Honestly I can deal with the whine as long as I know the differential is operating correctly.

I am going to change the fluid and see if that helps.

Is there an easy way to identify whiteline bushings while the car is lifted?

My buddy works at a shop with a lift so we can use that when replacing the diff fluid.