Differential Noise after fluid change

[aswy6]

Hi everyone wanted to share my story here and see if this happened to someone else.
F80 M3 with 50k miles here, last time i changed diff fluid was at 30k miles at the shop and everything was fine. Just now changed it again at 50k and getting 2 types of weird sounds:
1) In the morning, very first tight turn i briefly hear a grind/slipping kind of noise from the rear for like 1 second.
2) Every time im making a tight turn while keeping the throttle input consistent and release the throttle mid turn, as long as the turn continues i hear a nasty grinding/slipping kind of noise as if something rotating is slipping against something.

This only happens when i release the throttle mid turn. Does anyone have any ideas what could be causing this? My only guess is that eLSD is disengaging something when i release the throttle and making something grind. What could be the case here?

The shop advised me to make 30 tight turns like figure 8 kind of deal and report back. They confirmed that OEM fluid was used and filled to correct level so they think it might be something else causing it.

Appreciate any input, is this something i should be worried about?

[spidy512]

howdy,

First, I am not sure I would go do 30 figure 8 turns. I have heard of this for new, mechanical LDS units, but not a simple fluid replacement. Possibly I am off.

As far as either of your noises that are new, neither sound good. I woud def think about having the shop take a look before driving it too much.

maybe others have more to add.

good luck! and keep us in the loop,

josh

[N44RP]

Did they use the correct fluid ie limited slip diff fluid of the right weight?
Sounds like there’s fluid without the limited slip modifier additive in there

[aswy6]

Originally Posted by N44RP

Did they use the correct fluid ie limited slip diff fluid of the right weight?
Sounds like there’s fluid without the limited slip modifier additive in there

Yeah they used OEM stuff. One of my friends told me that same thing happened to his F80 but it went away after 2 weeks. Hopefully mine will go away as well when i come back from vacation

[aswy6]

So i dod bunch of figure 8s and immediately after does not seem to help much. Still same sound when throttle is released mid turn. Some shops told me that its normal after the fluid change and should go away soon so lets see

[N44RP]

Originally Posted by aswy6

So i dod bunch of figure 8s and immediately after does not seem to help much. Still same sound when throttle is released mid turn. Some shops told me that its normal after the fluid change and should go away soon so lets see

Damn, those figure 8s worked on the older cars after a diff fluid change. Surprised it didn’t solve your issue.

[aswy6]

Originally Posted by N44RP

Damn, those figure 8s worked on the older cars after a diff fluid change. Surprised it didn’t solve your issue.

I actually just came back from the shop that did the work. They pulled a sample of fluid and said it looks fine, no metal shavings and not dark. They think that something else going on not diff related however they were not able to find anything. I personally think its the diff as well. Im about to drive down from Seattle to Laguna Seca and shop told me to send it and wait until something brakes. Hopefully i can make it home after lol.
Also some other shops told me that this is somewhat common with eDiffs and that sound should go away. Maybe helpful to note that i also have has GTS Diff coding for about 10k miles or so, maybe thats somehow affecting something.

[SYT_Shadow]

Non OEM oil many times does not have friction modifier, which makes the diff quieter and also reduces diff locking abilities.

Unless you saw the oil go in I would not be so sure that it's OEM. Everyone makes mistakes, some more than others. What would concern me most is fluid level, so if the fluid level is ok I'll sleep at night.

The 'figure 8' thing is to distribute oil in between clutches. An ediff has clutches, just like a regular LSD, so the same idea applies to both.

I don't think GTS coding has anything to do with it. If the sound really bothers you, get the fluid changed again. This could be perfectly benign, like OE fluid that doesn't have FM, to potentially serious like insufficient fluid or completely wrong fluid.

[aswy6]

Originally Posted by SYT_Shadow

Non OEM oil many times does not have friction modifier, which makes the diff quieter and also reduces diff locking abilities.

Unless you saw the oil go in I would not be so sure that it's OEM. Everyone makes mistakes, some more than others. What would concern me most is fluid level, so if the fluid level is ok I'll sleep at night.

The 'figure 8' thing is to distribute oil in between clutches. An ediff has clutches, just like a regular LSD, so the same idea applies to both.

I don't think GTS coding has anything to do with it. If the sound really bothers you, get the fluid changed again. This could be perfectly benign, like OE fluid that doesn't have FM, to potentially serious like insufficient fluid or completely wrong fluid.

Thanks a lot for the input! The shop confirmed many times that the correct fluid was used and that it was filled to correct level. They looked at it again today and took a fluid sample and then filled it a little bit again. I mean thats a complete fiasco if wrong fluid was used but they swear that correct fluid was filled and i showed them the picture of it and they confirmed that its indeed what was used. I was trying to ask the shop to put Redline diff fluid in but they talked me out of it and recommended to stick with OEM.

So afterall you think everything is fine and clutches will brake in and sound will go away? Whats weird is that it happens only upon abrupt release of throttle when wheel at full lock and it feels like something is not disengaging all the way and grinds.

[SYT_Shadow]

Originally Posted by aswy6

Thanks a lot for the input! The shop confirmed many times that the correct fluid was used and that it was filled to correct level. They looked at it again today and took a fluid sample and then filled it a little bit again. I mean thats a complete fiasco if wrong fluid was used but they swear that correct fluid was filled and i showed them the picture of it and they confirmed that its indeed what was used. I was trying to ask the shop to put Redline diff fluid in but they talked me out of it and recommended to stick with OEM.

So afterall you think everything is fine and clutches will brake in and sound will go away? Whats weird is that it happens only upon abrupt release of throttle when wheel at full lock and it feels like something is not disengaging all the way and grinds.

I had a shop that's highly reputed here swear up and down that the alignment printout was wrong and the car was actually aligned correctly. After spending a few more hours of my life taking the car back, surprise surprise, the printout was not wrong.

Wheels at full lock are a tough situation for a LSD. That's why FM was added to the OEM fluid: too many customers were complaining about the diff acting up precisely in that situation.

Had you been tracking it for a long time I'd suggest recalibrating the diff. There's supposed to be a way to do it to account for wear IIRC. Still, I don't see what that has to do with a fluid change.

If it were my car I'd change the fluid in my driveway if necessary, because if the fluid is really correct then it's either a matter of fluid working its way into everything or the diff may be on its way out. Or, some odd noises when you first picked it up have made you focus on the diff and you're hearing things that are normal.

[aswy6]

Originally Posted by SYT_Shadow

I had a shop that's highly reputed here swear up and down that the alignment printout was wrong and the car was actually aligned correctly. After spending a few more hours of my life taking the car back, surprise surprise, the printout was not wrong.

Wheels at full lock are a tough situation for a LSD. That's why FM was added to the OEM fluid: too many customers were complaining about the diff acting up precisely in that situation.

Had you been tracking it for a long time I'd suggest recalibrating the diff. There's supposed to be a way to do it to account for wear IIRC. Still, I don't see what that has to do with a fluid change.

If it were my car I'd change the fluid in my driveway if necessary, because if the fluid is really correct then it's either a matter of fluid working its way into everything or the diff may be on its way out. Or, some odd noises when you first picked it up have made you focus on the diff and you're hearing things that are normal.

I can replicate the diff noise every time by letting off the throttle mid corner when at full lock. The shop drained a little bit of fluid today to looks at color and metal shavings. Everything was perfect. Car also drives perfect. For now i guess im going to assume that fluid takes some time getting into clutches and what not? Also, if lets assume they put the wrong fluid in there, am i basically screwed if i go with it to the track?

[SYT_Shadow]

Originally Posted by aswy6

I can replicate the diff noise every time by letting off the throttle mid corner when at full lock. The shop drained a little bit of fluid today to looks at color and metal shavings. Everything was perfect. Car also drives perfect. For now i guess im going to assume that fluid takes some time getting into clutches and what not? Also, if lets assume they put the wrong fluid in there, am i basically screwed if i go with it to the track?

diffs are fairly robust devices. If they used OE fluid that doesn't have FM then your diff will work better than it has in the past for track use.

Just use it, if it gets really noisy over the track day, stop

[aswy6]

Originally Posted by SYT_Shadow

diffs are fairly robust devices. If they used OE fluid that doesn't have FM then your diff will work better than it has in the past for track use.

Just use it, if it gets really noisy over the track day, stop

Got it, thanks for the input! For now im going to assume that correct fluid was used and it just needs some time to get into places. Attached a photo of the fluid that was used.

[SYT_Shadow]

Originally Posted by aswy6

Got it, thanks for the input! For now im going to assume that correct fluid was used and it just needs some time to get into places. Attached a photo of the fluid that was used.

time to send it

[ONEof500]

Our cars are not supposed to have friction modifiers. OEM does not have.
edycol

Been very happy with gear competition (left side)

[lgiambalvo540]

I had my diff fluid changed by local BMW dealer, and there was absolutely no noise following the change.

[SYT_Shadow]

Originally Posted by lgiambalvo540

I had my diff fluid changed by local BMW dealer, and there was absolutely no noise following the change.

I've had mine changed a couple times at BMW as well, zero difference

[2015F80]

This is correct fluid.

The dealer showed me this on the parts diagram on their computer. So this is what bmw recommends for an f80 m3. This is what I put in mine and no problems.

Maybe try to change your fluid with this one

https://f80.bimmerpost.com/forums/sh....php?t=1639333

[aswy6]

Originally Posted by 2015F80

This is correct fluid.

The dealer showed me this on the parts diagram on their computer. So this is what bmw recommends for an f80 m3. This is what I put in mine and no problems.

Maybe try to change your fluid with this one

https://f80.bimmerpost.com/forums/sh....php?t=1639333

Part number on the phot does not match part number in that thread though

[jfritz27]

Don't know if this could be it, but... was it re-filled all the way? In many places it is quoted that 1 L is all you need, but when I DIY'd mine and drained it dry with the fluid warm, I needed maybe 1.1 - 1.2 L of fluid to refill it to the point of the fluid dripping back out the fill hole. I have no idea whether being slightly under on fluid by that amount should explain your issue, but something to consider.

[N44RP]

You ever get this resolved?

[aswy6]

Originally Posted by N44RP

You ever get this resolved?

Yes. So after changing the fluid, the sound appeared. I drove for 2 weeks then drove from Seattle to Monterey which is about 1k miles. Before going out for my first session at Laguna Seca, i was able to easily replicate the sound. But i went on with the fact that if it breaks it breaks and went ahead to do my first session without sending it too hard. As soon as i came back from my first session, i was not able to replicate the sound anymore. After i was done with track day, i drove home to Seattle and still not able to replicate the sound. So TLDR, track fixed it 🤷*♂️