Rear diff or Transmission whine?

[SukSqueezeBangBlo]

Hey all,

I've noticed when in 4th,5th gear around 2k-3k rpm's i hear a slight whine when on the throttle. It goes away when i'm off the throttle. Possibly coming from the diff or maybe manual transmission? Anyone else experience this?



Thanks!

PS: Rear diff bolts are secure and not cracked and everything seems to be fine. I had the rear diff fluid changed and noticed no difference in the noise...

[dparm]

Originally Posted by Mattgfx

Hey all,

I've noticed when in 4th,5th gear around 2k-3k rpm's i hear a slight whine when on the throttle. It goes away when i'm off the throttle. Possibly coming from the diff or maybe manual transmission? Anyone else experience this?



Thanks!

PS: Rear diff bolts are secure and not cracked and everything seems to be fine. I had the fluid changed and noticed no difference in the noise...

Just to be clear on a few things (sorry if these seem obvious, but just trying to rule things out):

1. Does this happen if the car is standing still and in neutral?
2. Does this happen if the car is standing still, but in gear with the clutch pedal to the floor?
3. Does this happen in said gears/throttle position if you are on a sweeping curve?
4. Does the whine get louder or higher pitched if you go faster?
5. For the fluids, what did you have put in there?


Having owned my M3 for almost 3 years, and based on what the owner's manual says, there are some inherently strange noises the car makes. It's just the nature of a vehicle that's this high-strung.

[dparm]

Originally Posted by DrFerry

Highly likely it's the differential nose bearing. Most of 'em do it even at low mileage. You should love this thread below:

http://www.m3post.com/forums/showthr...1138005&page=5

Might want to consider a diff oil change just in case. I recommend the Red Line 75W140 which has more cushioning power than the 75W90 oem stuff, and its cheaper.. Just my $0.02.

http://www.redlineoil.com/product.aspx?pid=134

The factory rear diff oil is 75w140, NOT 75w90. Specifically, it is Castrol SAF-XJ (now called Syntrax Limited Slip) with additional friction modifier.

The manual trans is MTF-LT-2, which is a 75w80.

[SukSqueezeBangBlo]

Originally Posted by dparm

Just to be clear on a few things (sorry if these seem obvious, but just trying to rule things out):

1. Does this happen if the car is standing still and in neutral?
2. Does this happen if the car is standing still, but in gear with the clutch pedal to the floor?
3. Does this happen in said gears/throttle position if you are on a sweeping curve?
4. Does the whine get louder or higher pitched if you go faster?
5. For the fluids, what did you have put in there?


Having owned my M3 for almost 3 years, and based on what the owner's manual says, there are some inherently strange noises the car makes. It's just the nature of a vehicle that's this high-strung.

Thanks for the response


1. Does this happen if the car is standing still and in neutral?
Nope
2. Does this happen if the car is standing still, but in gear with the clutch pedal to the floor?
Nope
3. Does this happen in said gears/throttle position if you are on a sweeping curve?
I believe so
4. Does the whine get louder or higher pitched if you go faster?
Slightly higher pitched but it will go away around 3100k+ rpms when in 4th,5th, gear
5. For the fluids, what did you have put in there?
BMW changed the rear diff fluid so whatever OEM is.

[dparm]

It could be the rear diff, or it could be nothing. If the car's under warranty, take it in and let the dealer see if they can isolate it. If nothing else, it'll be recorded as a potential problem so that if something does break, they'll be more likely to help.

I would just keep driving it and monitor the sound.

[SukSqueezeBangBlo]

Originally Posted by dparm

It could be the rear diff, or it could be nothing. If the car's under warranty, take it in and let the dealer see if they can isolate it. If nothing else, it'll be recorded as a potential problem so that if something does break, they'll be more likely to help.

I would just keep driving it and monitor the sound.

Thanks, it's not under warranty and has 63k miles.


Anyone else have this issue while driving in 4 / 5 gear(manual) around 2500rpms? Slight whine noise

EDIT:
After doing some testings its 4/5th gear 2500 rpm and mainly part throttle.