low speed turns making noise (resolution: new diff / differential fluid)

Just got the BMW Diff fluid changed in my car @ EAS, diff is quiet now. The whhhrrr-whhhrrr-whhhrrr noise was getting irritating on my car. 70k miles on the odo.

37K miles and have loud diff whomp whomp whomp noise turning at slow speeds around tight corners, right is worse than left. It actually starts jerking the car at times when it grabs. Is there a diff lube replacement cycle around this mileage that I need to do or a topping off schedule? Any DIYs?
thanks.

I specifically asked for the non-FM version when I got my fluid changed at 26K. The FM version is a BMW modification from Castrol's formula and intended solely to quiet the diff, which combined with the fact that it's not listed for use outside the US makes me wonder if BMW created this variant just to appease whiny Americans and potentially achieved quieter operation at the cost of performance. I definitely have diff noise when cold and turning corners at low speeds, but seeing as I enjoy my car at the track, I'll take that over reduced performance without hesitation.

UPDATE: Yep, turns out that friction modifiers decrease noise by decreasing performance. New post later in this thread: http://www.m3post.com/forums/showpost.php?p=19918102&postcount=63.

TX wrote

37K miles and have loud diff whomp whomp whomp noise turning at slow speeds around tight corners, right is worse than left. It actually starts jerking the car at times when it grabs. Is there a diff lube replacement cycle around this mileage that I need to do or a topping off schedule? Any DIYs?
thanks.

Change the fluid, immediately.

http://www.m3post.com/forums/showthread.php?t=714350

For info my car's diff made the cold oil, low speed groan on turns since I bought it with 3k miles and I have resisted having the diff oil with extra friction modifier added.
Now 5 years later and at 50k miles it still makes exactly the same noise and still fully locks up when required.

Is there an issue going back to regular/ non-FM fluid? At 1200 mile service, dealer put in the regular/ non-FM fluid. At 30k mile service, the same dealer put in the fm fluid, but I never had an issue with noise. I did not know they put the fm fluid until the work was done and I saw the work invoice. I told them about it after but it was too late. They said it is the only fluid they carried/ dealer excuse. I will be doing my 60k mile service soon. Thanks in advance for the response.

I asked this same question in the DIY: Differential Fluid Change thread in the DIY section almost a week ago with no response. Link below. I'm hoping more foot traffic in the general section will give me a response.

http://www.m3post.com/forums/showthread.php?t=714350&page=3

1sikbmr wrote

This Service Information bulletin supersedes SI B33 01 02 dated February 2008.

SUBJECT
Grinding Noise from the Differential during Slow Cornering


MODEL
E46 M3 from start of production

E60 M5 from start of production

E63, E64 M6 from start of production

E90, E92 and E93 M3 from start of production


SITUATION
A grinding noise may be heard coming from the differential during slow cornering.

This noise is best heard during tight cornering situations.
For example : while parallel parking, driving in a tight circle, etc.

CAUSE
When the rear wheel speed differential varies during tight cornering, a slip stick effect is created on the lining and steel discs incorporated in the differential locking clutch, causing the grinding noise.

This noise typically goes away as the locking clutch discs in the differential are broken in.

The break-in time varies depending on driving habits.
For example : tighter cornering (working the locking clutch) means that it takes less time to break in the locking clutch discs.

CORRECTION
If a complaint is verified as described above on the E46 M3; E60 M5; E63 and E64 M6; or on the E90, E92 and E93 M3 vehicles, the differential oil should be replaced with a specially formulated differential oil, BMW part number 83 22 2 282 583.

Road test the vehicle. (the part I hate the most and every other technician.perhaps most of them skip this part.I would rather give you the option to perform this or at least inform you of this procedure.)

With the vehicle at operating temperature
Drive in tight circles (20 circles in each direction), allowing the special oil to coat the locking clutch discs.

The grinding noise will decrease when the locking clutch discs are sufficiently coated. Some slight noises may still be heard after driving in tight circles. Its necessary to drive the vehicle up to 600 miles before all noises are eliminated as stated by the manufacturer.

Note: Vehicles that have had the differential oil converted to this special oil should continue to use this oil whenever a service requiring the differential oil replacement is indicated.

I test drove an M3 that was making this noise last weekend. It was a 2011 model year. I then drove a 2013, and it made the same noise.
In my experience, it is best to be able to provide the Technical or Service Bulletin number to the service writer on an issue where one has the BMW heads up on it.

Curious if anyone has got the new fluid with the friction modifier and it didn't resolve the issue?

I have about 300 miles on the new fluid with the FM and so far no improvement at all. In fact the car actually seems to be making the noise more often and louder. I've done the circles thing multiple times as well. Going to do a short road trip just to get the rest of the miles in so the dealer will look at it again.

Ha. That's nice it's only the fluid. I wasted my diff. Now have OS Giken. No more peg leg or stability control intervention

what spec of the osg?
the non-locking stock setup or something improved?

Spec? I don't know the shop ordered it. It's tuneable and they changed the setup a few times. It's night and day. My stock LSD was garbage. It's a completely different animal.

they'd changed the setup a few times?!
very interesting! so they had a testdriver try it and then took it out, changed the setup, tried again and so on? so what setups did they try and what was the according result? i'd be VERY interested in their findings...

that the stock unit is garbage is nothing new to me... but a proper working os giken would indeed be a new thing to me! ;-)

astris wrote

Curious if anyone has got the new fluid with the friction modifier and it didn't resolve the issue?

I have about 300 miles on the new fluid with the FM and so far no improvement at all. In fact the car actually seems to be making the noise more often and louder. I've done the circles thing multiple times as well. Going to do a short road trip just to get the rest of the miles in so the dealer will look at it again.

Update: I have over 1k miles on the new fluid with zero improvement. Taken it to the dealer twice now and they won't do anything. The shop foreman said it's "normal." It grinds and even shakes the car every single time I drive when it's cold. Sorry, no chance in hell that's normal. I have no idea what to do now since they won't even address it. Suggestions?

It's a diff, it's spose to make that noise under tight cornering If it didn't I'd doubt the diff is any good.

astris wrote

Update: I have over 1k miles on the new fluid with zero improvement. Taken it to the dealer twice now and they won't do anything. The shop foreman said it's "normal." It grinds and even shakes the car every single time I drive when it's cold. Sorry, no chance in hell that's normal. I have no idea what to do now since they won't even address it. Suggestions?

It does this when turning or heading straight? After they used the new FM fluid, did they perform a series of figure 8s in a parking lot somewhere to help distribute the fluid? 1000 miles isn't quite a lot to get fluid moved around the clutch plates.

I will say your foreman is correct, it is normal and has occurred with every M diff I've owned, when it's cold.

I've never used any of the FM boosted stuff as it takes away from the locking differential job. It's only for people who don't know any better and think the car will fall apart due to the noise.

Took mine in for the fluid change today and the only difference so far is that I'm $245 poorer than when I dropped it off. The biggest rip off since the Pet Rock.

Quicksilv3r wrote

Took mine in for the fluid change today and the only difference so far is that I'm $245 poorer than when I dropped it off. The biggest rip off since the Pet Rock.

Don't run the OEM fluid. It's a total rip off.

I run Royal Purple, just changed the rear diff fluid, no noises, and only about 15 $ a bottle.

I bought my car 2 months ago and have been experiencing this issue. It's an 08 manual m3 with 43k miles on the clock. I was just wondering whether there has been any issues with not changing the fluid? as this thread seems to date back to 2012. I can live with the noise and an extra $245 bucks in my pocket (that I would save from dealer diff fluid change) but am just really worried about it damaging the diff in the long run?

Resurrecting this thread again because after doing a bunch of research on LSD friction modifiers looking into what to put into my GT4, I've gotten confirmation from several sources of what I had already suspected, namely that these FM boosters are purely for NVH and they accomplish their goal (reducing noise) by reducing the effectiveness of the diff.

If you look at Red Line's own product pages, for example, for the versions of their products that have friction modifiers, they say that they "provide additional slipperiness", which is exactly what you DON'T want if you want an LSD to actually do its job rather than just sit quietly in your driveline. Matt Monson of Guard Transmission, a very well-respected vendor of custom diffs and custom MT gears for Porsches (and maybe other makes?) also confirms that these friction modifiers reduce lockup. And yes, I'm aware that Red Line specifically recommends the non-NS version (i.e. the one with friction modifiers) for M car diffs, which I assume is because the NS version that lacks them might be TOO harsh for this application, but my point is that having more friction modifier than is actually needed for the diff to do its job will be detrimental to performance, and that's what BMW did to their own diff oil when they created the +FM booster version in response to customer complaints about noise.

I stayed away from the +FM version of the diff oil because it seemed strange to me that it was made by BMW off of a Castrol formula (whereas the original version was an unadulterated Castrol product), it was only listed as an option in the US rather than globally, and it was only available upon request from customers who complained about noise -- even though the original XJ and the XJ +FM versions cost basically the same from the dealer, at least when I checked. If the +FM version had been an overall improvement, I'd have expected it to be listed globally and just have become the standard fill going forward. So I guess if you drive your car in a way that doesn't take advantage of an LSD, then by all means go with the +FM version, but if you're driving the M3 as intended, i.e. adding throttle mid-corner (especially at the track), then deal with a bit of noise in tight corners when the driveline is cold in exchange for better performance.

Radiation Joe wrote

Ahhhh!
So it's diff fluid causing this grinding sound from the rear end that has been bothering folks with this car for years.
It's awesome that someone finally figured this out. I hope in the future that people search the forum when this happens to them. They will be able to find this very helpful thread that obviously no one had ever thought to post before.

That did just happen to me!

jphughan wrote

Resurrecting this thread again because after doing a bunch of research on LSD friction modifiers looking into what to put into my GT4, I've gotten confirmation from several sources of what I had already suspected, namely that these FM boosters are purely for NVH and they accomplish their goal (reducing noise) by reducing the effectiveness of the diff.

If you look at Red Line's own product pages, for example, for the versions of their products that have friction modifiers, they say that they "provide additional slipperiness", which is exactly what you DON'T want if you want an LSD to actually do its job rather than just sit quietly in your driveline. Matt Monson of Guard Transmission, a very well-respected vendor of custom diffs and custom MT gears for Porsches (and maybe other makes?) also confirms that these friction modifiers reduce lockup. And yes, I'm aware that Red Line specifically recommends the non-NS version (i.e. the one with friction modifiers) for M car diffs, which I assume is because the NS version that lacks them might be TOO harsh for this application, but my point is that having more friction modifier than is actually needed for the diff to do its job will be detrimental to performance, and that's what BMW did to their own diff oil when they created the +FM booster version in response to customer complaints about noise.

I stayed away from the +FM version of the diff oil because it seemed strange to me that it was made by BMW off of a Castrol formula (whereas the original version was an unadulterated Castrol product), it was only listed as an option in the US rather than globally, and it was only available upon request from customers who complained about noise -- even though the original XJ and the XJ +FM versions cost basically the same from the dealer, at least when I checked. If the +FM version had been an overall improvement, I'd have expected it to be listed globally and just have become the standard fill going forward. So I guess if you drive your car in a way that doesn't take advantage of an LSD, then by all means go with the +FM version, but if you're driving the M3 as intended, i.e. adding throttle mid-corner (especially at the track), then deal with a bit of noise in tight corners when the driveline is cold in exchange for better performance.

But this did just caught up my attention.