Rear-end / Differential / Drivetrain Noise?

[youngsj]

Hi Guys - I've got ~400 miles on my new M3 6MT sedan and I'm getting this subtle groan/whirring noise coming from the rear (I think it's on the driver's side rear). At first I thought it might be a bearing, but I gave up on that theory because it goes away the instant I take it out of gear or depress the clutch.

Believe it or not, but the noise occurs in any gear...but only at 43 miles per hour!

It does not make the sound unless you are in gear...and although it will make the noise in any gear at 43 mph, it is most pronounced while in 4th. I think this is because 43 mph in 4th is a pretty even-tempered and quiet ride (in other words not-too-fast and not-too-slow). Also, it is best reproducible if I am feathering the gas...it generally goes away if I press firmly on the gas, and also generally goes away if I let off the gas totally (engine braking).

I've done a lot of searching on this noise on the internet and within these forums, and I've read a few posts where people describe a slight clunking, or some people describe a minor grinding when turning...my noise is not like that. The noise I'm hearing occurs regardless of whether I'm going straight or in a turn, and it sounds like a groaning/whirring sound.

I took it to my dealer today, and took the shop foreman for a road test. Luckily he did say he could hear it. He said he was going to contact BMW and also try to drive a few others (they've got a coupe on the lot)...and then he'd give me a call with an update.

Anyways...it is a quiet sound - but my commute is largely back roads, so I'm frequently in 4th going between 40-50 mph and so I hear this noise all the time - it's bugging the crap out of me.

Thanks for any help you guys can offer.

[KonigsTiger]

Well, I hope its nothing serious, I haven´t hear anything after almost 2,500 kilometers. Can you hear it better with the windows open?

[Technic]

Originally Posted by youngsj

Hi Guys - I've got ~400 miles on my new M3 6MT sedan and I'm getting this subtle groan/whirring noise coming from the rear (I think it's on the driver's side rear). At first I thought it might be a bearing, but I gave up on that theory because it goes away the instant I take it out of gear or depress the clutch.

Believe it or not, but the noise occurs in any gear...but only at 43 miles per hour!

It does not make the sound unless you are in gear...and although it will make the noise in any gear at 43 mph, it is most pronounced while in 4th. I think this is because 43 mph in 4th is a pretty even-tempered and quiet ride (in other words not-too-fast and not-too-slow). Also, it is best reproducible if I am feathering the gas...it generally goes away if I press firmly on the gas, and also generally goes away if I let off the gas totally (engine braking).

I've done a lot of searching on this noise on the internet and within these forums, and I've read a few posts where people describe a slight clunking, or some people describe a minor grinding when turning...my noise is not like that. The noise I'm hearing occurs regardless of whether I'm going straight or in a turn, and it sounds like a groaning/whirring sound.

I took it to my dealer today, and took the shop foreman for a road test. Luckily he did say he could hear it. He said he was going to contact BMW and also try to drive a few others (they've got a coupe on the lot)...and then he'd give me a call with an update.

Anyways...it is a quiet sound - but my commute is largely back roads, so I'm frequently in 4th going between 40-50 mph and so I hear this noise all the time - it's bugging the crap out of me.

Thanks for any help you guys can offer.

The E46 M3 used to have the same issue... a change of differential oil type cured it.

[youngsj]

Hmm - haven't tried a close listen with the windows down, but that's a good idea because it would probably help alot if I could determine exactly where it was coming from. It is very subtle...not obnoxious, or loud - it just doesn't sound right on a car that is engineered for speed.

My wife heard it while sitting in the passenger seat, so I had planned on asking her to change positions between pass front > pass rear > driver rear and see if she could hear it more pronounced in one position over the other - maybe I'll do this experiment with the windows down too.

Technic - do you happen to know the exact type of differential oil that took care of this in the e46 m3?

[nusevad]

I think i have the same whirling noise. I never though too much of it because i though its coming from the engine.

Ill pay more attention when i drive tomorrow.

[youngsj]

FifthStreetz - thanks for the response...It'd be interesting if you're getting this subtle whine/whirring noise in 4th gear at 43 MPH too - please let me know.

As an update - The foreman at my dealer called me back and said that he talked to BMW and they were not aware of this noise, and that they had not had any customer reports as of yet...other than mine - who knows if this is just BS to quiet me down?

He also said that he had the chance to take the M3 6MT coupe that they have for sale on the lot for a road test...and he said that he was able to hear the noise in 4th gear at 43 MPH in that M3 as well.

...Then he told me that there is not much he can do at this point, and that it is what it is...

I guess my plan is to monitor this thread for reports from others and drive through the rest of the break-in period (eg: another 700 miles) and see if it improves or goes away. If it does not, then I'm gonna go in and ask to drive the coupe to see if I can hear it in the coupe...if I can hear it then I'll back off...if I can't hear it then I'm going to get a little knarly and start demanding additional scrutiny and next steps to address it.

[ersin]

Sounds like a good plan. But I hope it's nothing. Weird that it is only at 43mph. Keep us posted. Thanks.

Good luck.

[nusevad]

I drove today and i noticed the whirling noise at low speeds, not specifically at one specific speed. Someone said that it is the LSD in another post.

[Romo]

My E46 M3 used to have the same problem, at slow speed, turning sharp 90 degree corners, I did hear some "grinding" ( is this a good word?) noise/sound.
It turned out to be the LSD. Problem could be solved by changing the LSD oil. It is a specefic LSD oil, the dealer had to order it, they didn`t have it in store.

[ScotyH]

I hear the same noise. I've driven a number of cars over the years and my conclusion is that the noise is merely a product of the tranny being more "connected" to the car.

What I hear is a whine. The tranny is just less isolated from the car which means you're going to hear every weird noise and clunk that it makes.

I think it's part of it being more of a performance car than a luxury ride.

[Technic]

Originally Posted by youngsj

Technic - do you happen to know the exact type of differential oil that took care of this in the e46 m3?

P/N 832 222 82 583 SAF-XJ + FM booster

Plenty to read here: http://www.m3forum.net/m3forum/showthread.php?t=86605

I may add that this oil change not necessarily cured all cases of differential noise/grinding.

[youngsj]

ScotyH - My noise is a quiet whine as well...definitely NOT a grinding. Your comments about the tranny being less isolated from the car are somewhat comforting, but I still wish I wasn't hearing the noise!

Technic - very, very interesting thread...thank you for getting back to me with the oil type and this information. The only thing, is that my noise is absolutely not a "grinding", "cabin boom", or "clatter" type noise - it is a more of a quiet whine/whirring and it occurs regardless of whether I'm driving straight ahead, in a turn, or in figure 8's. It is best heard in 4th gear after driving for a bit (fully warmed up)...and most proiminent as I feather the gas at speeds between 40-45 mph - it completely goes away when below 40 mph or above 45 mph.

I wonder if the "P/N 832 222 82 583 SAF-XJ + FM booster" diff fluid will help my situation even though my noise happens while driving straight ahead and is not a "grinding", "cabin boom", or "clatter"?

It wouldn't bother me as much as it is if the noise was present all the time...the reason it's getting my attention is because it comes & goes everytime I am casually driving at speeds between 40-45 mph - which is basically my entire commute to and from work (eg: since I take back roads to the office).

Anyway - thanks for everyone's help with this...I guess I'll just chock this up as a personality of the car that I learn to love!

[Technic]

Originally Posted by youngsj

ScotyH - My noise is a quiet whine as well...definitely NOT a grinding. Your comments about the tranny being less isolated from the car are somewhat comforting, but I still wish I wasn't hearing the noise!

Technic - very, very interesting thread...thank you for getting back to me with the oil type and this information. The only thing, is that my noise is absolutely not a "grinding", "cabin boom", or "clatter" type noise - it is a more of a quiet whine/whirring and it occurs regardless of whether I'm driving straight ahead, in a turn, or in figure 8's. It is best heard in 4th gear after driving for a bit (fully warmed up)...and most proiminent as I feather the gas at speeds between 40-45 mph - it completely goes away when below 40 mph or above 45 mph.

I wonder if the "P/N 832 222 82 583 SAF-XJ + FM booster" diff fluid will help my situation even though my noise happens while driving straight ahead and is not a "grinding", "cabin boom", or "clatter"?

It wouldn't bother me as much as it is if the noise was present all the time...the reason it's getting my attention is because it comes & goes everytime I am casually driving at speeds between 40-45 mph - which is basically my entire commute to and from work (eg: since I take back roads to the office).

Anyway - thanks for everyone's help with this...I guess I'll just chock this up as a personality of the car that I learn to love!

I would guess that whatever caused the E46 M3 differential noises have to be gone now from the E9x M3, especially the right type of differential oil should be filled into the differential now. So I don't think that you need to be concerned about changing the type of oil in the differential, although in the E46 M3 a differential oil change was part of the 1200 service.

I don't now if the E9x M3 requires a diff oil change also at 1200 miles, but it could be a good idea to ask for one if this bothers you that much. At least a rear suspension/drivetrain inspection is warranted.

[dawgdog]

Originally Posted by Technic

The E46 M3 used to have the same issue... a change of differential oil type cured it.

+1

[!Xoible]

ah ha! i was gonna post about this noise. my tranny seems to only get noisier. it's scaring me actually. like the harder i drive the noisier it gets.

[lucid]

The previous generation M3s I drove had some kind of a whine as well, and so does this car. I don't think it is anything to worry about, but without hearing it, it is difficult to know if we are all referencing the same noise or not.

[Pancho]

I already have 5,000 Kms. and have not heard such noise. At that speed I am just cruising comfortably even in Mexican roads.

[STALKER]

Im getting this noise too, any updates?
My car is going to the dealer on Monday.

[sello]

anyone have any more info on this...mine has been doing it for a while..So damn annoying. is it normal?

[adc]

Guys, just get the tech to reproduce or hear it, and to write it down in your record. That way should something bad happen later on, BMW will honor the fix - in most cases even after the warranty.

Documentation is key. Next, is a good Service Advisor.

[tibra1]

Good Lord..I cant believe these threads still going on.,

You are in a car with a clutch type LSD...

YES it makes noise, especially when cold, making tight radius turns and in the break in phase..once you do the break in service and swap the diff fluid things will quiet down a whole lot with only the occasional groan when cold and turning.

[Blotman]

If you hear a howling noise from the rear during a sharp turn (could be done at low speeds), then it's probably the issue with the differential fluid mentioned earlier. BMW has a service bulletin for this and will replace the fluid under warranty. Even if it's not that, take it into BMW anyway.