11-23-2021, 10:06 PM | #1 |
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Differential Noise after fluid change
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? |
11-23-2021, 10:37 PM | #2 |
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Drives: 2015 f80 M3
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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 |
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12-03-2021, 10:32 AM | #4 |
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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
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12-06-2021, 08:29 AM | #6 |
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Damn, those figure 8s worked on the older cars after a diff fluid change. Surprised it didn’t solve your issue.
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12-06-2021, 11:10 AM | #7 | |
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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. |
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12-06-2021, 12:39 PM | #8 |
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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. |
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12-06-2021, 01:01 PM | #9 | |
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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. |
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12-06-2021, 02:10 PM | #10 | |
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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. |
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12-06-2021, 02:14 PM | #11 | ||
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12-06-2021, 02:59 PM | #12 | |
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Just use it, if it gets really noisy over the track day, stop |
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12-06-2021, 03:01 PM | #13 | ||
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12-06-2021, 03:08 PM | #14 |
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time to send it
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12-08-2021, 02:52 PM | #17 |
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I've had mine changed a couple times at BMW as well, zero difference
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12-08-2021, 09:46 PM | #18 |
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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
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12-08-2021, 09:48 PM | #19 | |
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12-09-2021, 07:14 AM | #20 |
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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.
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12-14-2021, 02:43 PM | #22 |
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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 🤷*♂️
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