DCT whine in certain MPH ranges, cause for concern & fixable?

[camF80]

Hi guys,

My F80 has what I believe is a DCT gear whine in the speed ranges of 45-55, and 70-80. It's only apparent on while on throttle, and increases in pitch as I get to the top of the MPH range its present at. The transmission doesn't clunk or have jerky shifts. Mechanically behaves perfectly fine, just has this really annoying noise in the speed ranges I drive most often and I want to know if its worth taking to the dealership to have diagnosed or not. I have a B2B warranty that should cover it but I have a feeling they're going to charge me a diagnosis fee and not do anything.

Worth mentioning I have the bimmer-remote/kubax GTS dct flash on my car, and that seemed to make it marginally quieter, 10% or so.

Anyone else have this issue and has anyone gotten it fixed? Did my best to get videos of it.

Thanks

https://www.youtube.com/shorts/qSnHnK0hu4E
https://www.youtube.com/shorts/o0podPtOZho

[M3SQRD]

Are you sure it’s the DCT and not the diff? Have you inspected your diff bushings lately? They’re a common failure point which could produce diff whine. I have three DCTs and all of them are quiet at all road speeds. Definitely find a dealership or Indy shop you trust. A diagnosis fee from a trustworthy shop will either identify an issue or give you confidence there’s no issue. What’s the mileage on your car and have you ever changed the DCT and diff fluids on your car? Changing fluids (use Pentosin OEM fluid instead of BMW labeled because it’s considerably cheaper for identical fluid. Redline or Motu DCTF fluids are great replacement options too) can sometimes quiet noises down. Depending on your mileage, a full DCT service might be warranted. lI’m surprised a GTS flash would have had any effect on a noise if it’s coming from the DCT. Did you also get the diff (GHAS) coded to GTS as well? I’m not familiar with a B2B warranty, what’s it stand for?

[camF80]

Originally Posted by M3SQRD

Are you sure it’s the DCT and not the diff? Have you inspected your diff bushings lately? They’re a common failure point which could produce diff whine. I have three DCTs and all of them are quiet at all road speeds. Definitely find a dealership or Indy shop you trust. A diagnosis fee from a trustworthy shop will either identify an issue or give you confidence there’s no issue. What’s the mileage on your car and have you ever changed the DCT and diff fluids on your car? Changing fluids (use Pentosin OEM fluid instead of BMW labeled because it’s considerably cheaper for identical fluid. Redline or Motu DCTF fluids are great replacement options too) can sometimes quiet noises down. Depending on your mileage, a full DCT service might be warranted. lI’m surprised a GTS flash would have had any effect on a noise if it’s coming from the DCT. Did you also get the diff (GHAS) coded to GTS as well? I’m not familiar with a B2B warranty, what’s it stand for?

Hey, thanks for the thorough reply!
I can't be 100% for certain its not the diff, but it does sound like its coming from directly underneath the shift knob. I'm sure I could find a trustworthy shop around here to give it a look, I appreciate the recommendation. 47k on the clock of the car, and I haven't personally changed the fluids, and I didn't see anything in the car fax prior to buying about them being changed. My next oil change is due at 50k and I was going to have the whole car done, oil, dct, diff. Yes I had the whole GTS package flashed onto the car- DCT, Diff, EDC, Power Steering, thats it I believe, which for the record made the car so much more enjoyable to drive. B2B is bumper to bumper, covers everything minus regular maintenance from the front bumper to the back. The car is out of factory warranty so I opted to have an extended dealership warranty put on it for the just in case.

[M3SQRD]

Originally Posted by camF80

Hey, thanks for the thorough reply!
I can't be 100% for certain its not the diff, but it does sound like its coming from directly underneath the shift knob. I'm sure I could find a trustworthy shop around here to give it a look, I appreciate the recommendation. 47k on the clock of the car, and I haven't personally changed the fluids, and I didn't see anything in the car fax prior to buying about them being changed. My next oil change is due at 50k and I was going to have the whole car done, oil, dct, diff. Yes I had the whole GTS package flashed onto the car- DCT, Diff, EDC, Power Steering, thats it I believe, which for the record made the car so much more enjoyable to drive. B2B is bumper to bumper, covers everything minus regular maintenance from the front bumper to the back. The car is out of factory warranty so I opted to have an extended dealership warranty put on it for the just in case.

One thing about DCTs is they are robust transmissions! Sorry you’ve got this variable whine issue. Does it make the whine noise over those speed ranges in any (possible) gear or is it only in specific gears only?

Fresh DCT and diff fluid at 50k miles may help although diff fluid at 100k miles still looks fresh! GTS package is all GTS except for EDC (GTS has conventional dampers) which is typically CS coded.

Ah, got it. I just couldn’t figure out what B2B stood for I remember in the 80s when new car warranties were referred to as B2B.

[camF80]

Originally Posted by M3SQRD

One thing about DCTs is they are robust transmissions! Sorry you’ve got this variable whine issue. Does it make the whine noise over those speed ranges in any (possible) gear or is it only in specific gears only?

Fresh DCT and diff fluid at 50k miles may help although diff fluid at 100k miles still looks fresh! GTS package is all GTS except for EDC (GTS has conventional dampers) which is typically CS coded.

Ah, got it. I just couldn’t figure out what B2B stood for I remember in the 80s when new car warranties were referred to as B2B.

Yeah, mechanically it feels fine it has no issue both normal driving and spirited. But, I live in Texas where everything is a highway so it keeps me squarely in the middle of annoying whine range for the majority of my driving. The videos I took don't really show how prominent it really is when in the car, which is unfortunate to try to diagnose with. I haven't noticed it being affected by certain gears, just the MPH range, which may back up the hypothesis that it's in the diff not the dct. I don't regularly drive fast enough over 80mph to have noticed it but some toll roads let me cruise at 95 and I've never heard it there. The whine changes pitches as I'm in its MPH range and its the most noticeable at 55 and 75 mph's.

[jfritz27]

Originally Posted by camF80

Yeah, mechanically it feels fine it has no issue both normal driving and spirited. But, I live in Texas where everything is a highway so it keeps me squarely in the middle of annoying whine range for the majority of my driving. The videos I took don't really show how prominent it really is when in the car, which is unfortunate to try to diagnose with. I haven't noticed it being affected by certain gears, just the MPH range, which may back up the hypothesis that it's in the diff not the dct. I don't regularly drive fast enough over 80mph to have noticed it but some toll roads let me cruise at 95 and I've never heard it there. The whine changes pitches as I'm in its MPH range and its the most noticeable at 55 and 75 mph's.

Have you tried putting it in neutral while cruising when it's making the noise and see if that alters it?

[MineralWhiteF80]

typically a whining noise at a certain speed range while on throttle is mostly commonly the rear differential. You can get the noise to audibly change a little bit with applying more or less throttle input, but overall if the noise is mainly speed related and not gear related, then it's good to think about the diff.

The F8x differentials are not imune to these whines and most whine more as they simply age. A torn differential bushing can contribute to the whine volume but still not show any 'bad diff bushing' symptoms yet. At 47k miles on the clock, you are within the window of possible bushing issues HOWEVER, I see you have a 2018 model year, and I believe they changed to the poly diff bushing (instead of fluid filled) in 2018 to correct this diff bushing noise problem. You can look at your diff bushing to confirm if you have the old version or the countermeasured newer style.

In 2016-ish, there was even a bulletin that BMW put out on F8x cars having loud diff noises where they recommended diff replacement but they also believed it only a select VIN range (production date) was affected and you would not be included in that.

[xwilkinx]

I notice this exact same whine in mine (also a DCT).

I've always thought this to be normal diff whine. I've actually replaced my rear diff along with the diff brace bushing and still have the same whine, so I don't see it as a need for concern!

I've noticed this on every single F8x I've driven (note that it's very quiet and I've really only heard it at low RPM with valves closed, typically with foot off the throttle).

[Imran2202]

Hi,
I have exactly the Same Problem with my f82 LCI. 3 mechanics from bmw told me its normal. One told me Bad transmission. If I put into N while driving Speed of 70-80 mph the white is immediatley away.

Die you Found out what the Problem is?

[M3SQRD]

Originally Posted by Imran2202

Hi,
I have exactly the Same Problem with my f82 LCI. 3 mechanics from bmw told me its normal. One told me Bad transmission. If I put into N while driving Speed of 70-80 mph the white is immediatley away.

Die you Found out what the Problem is?

Have you checked to hear whether the sound changes or stays the same in different gears? How many miles does your car have? MT or DCT?

[Imran2202]

Originally Posted by M3SQRD

Have you checked to hear whether the sound changes or stays the same in different gears? How many miles does your car have? MT or DCT?

I have DCT with 50.000 km. The whining is hearable in 6 and 7 Gear but only in Speed of 70-80 mph. Seems to be a Problem, which more people have..

[M3SQRD]

Originally Posted by Imran2202

I have DCT with 50.000 km. The whining is hearable in 6 and 7 Gear but only in Speed of 70-80 mph. Seems to be a Problem, which more people have..

So in lower gears does it go away or you can’t hear it because it’s been drowned out by exhaust noise, engine noise, etc.?

[Imran2202]

Originally Posted by M3SQRD

So in lower gears does it go away or you can’t hear it because it’s been drowned out by exhaust noise, engine noise, etc.?

I think I can hear it also in loser gears but very very quietly. For people who dont know the Problem Not hearable. Just at the specified Speed for People who dont know it. Its exact the Same Noise from the Video, when you take Away foot from Gas.
Any idea??
Thanks

[M3SQRD]

Originally Posted by Imran2202

I think I can hear it also in loser gears but very very quietly. For people who dont know the Problem Not hearable. Just at the specified Speed for People who dont know it. Its exact the Same Noise from the Video, when you take Away foot from Gas.
Any idea??
Thanks

If you hear it in all gears and any road speed then it’s definitely diff whine. The noise you typically hear when getting off the throttle is diff whine. It’s the only happens between 70-80 mph and putting DCT into neutral and it goes away suggests it’s not diff whine. The fact that you hear it in multiple gears suggests it’s not the DCT or a specific gear/shaft/clutch.

[Imran2202]

Originally Posted by M3SQRD

If you hear it in all gears and any road speed then it’s definitely diff whine. The noise you typically hear when getting off the throttle is diff whine. It’s the only happens between 70-80 mph and putting DCT into neutral and it goes away suggests it’s not diff whine. The fact that you hear it in multiple gears suggests it’s not the DCT or a specific gear/shaft/clutch.

Thanks i appreciate your help!!
So any idea Maybe what to do? What do you guess is the Problem? Oilpump for Trans Maybe? What would you do?

I spend 3k last week for a Bad valvetronic… the eccentricshaft looked very Bad. Still thinking over where this Problem came from.. Dealer Said it can be from the original bmw oil and only 3 changes in 40.000 Miles. Cant believe that, because every Service was made by bmw as planned from them.. this car makes me very overthinking by the time..

[gerri]

Originally Posted by Imran2202

Cant believe that, because every Service was made by bmw as planned from them..

For this car, BMW Europe recommends oil changes every two years or 30K km, but it is absurd to think of doing 30K km with the same oil, especially with an engine that has two turbos and more than 400HP. This way it is easier to have problems with the turbos or other engine components, i don't know why BMW recommends this mileage. Most owners change it at 8K km (me included) or at most 10K km. Three oil changes in 64K km are more than right for BMW but are few for those who care about their engine.

[M3SQRD]

Originally Posted by Imran2202

Thanks i appreciate your help!!
So any idea Maybe what to do? What do you guess is the Problem? Oilpump for Trans Maybe? What would you do?

I spend 3k last week for a Bad valvetronic… the eccentricshaft looked very Bad. Still thinking over where this Problem came from.. Dealer Said it can be from the original bmw oil and only 3 changes in 40.000 Miles. Cant believe that, because every Service was made by bmw as planned from them.. this car makes me very overthinking by the time..

Yours is a tough one to diagnose. If it makes the noise in any gear and only between a specific speed range but goes away when DCT is put into neural would point to the trans and possibly the engine, not the diff. But if it was the engine, then the noise would be at different speed ranges for different gears (i.e., engine rpm range, not road speed range). As for what part of the DCT, it’s to isolate because it only makes the noise between a certain speed range. It’s definitely a resonance of some kind due to it only happening within a specific speed range. It’s like not the tires/wheels because the noise goes away when the DCT is in neutral. 50k km is well within the DCT fluid life/change interval. Where does the sound appear to come from - in front you, under/beside you or behind you?

Originally Posted by gerri

For this car, BMW Europe recommends oil changes every two years or 30K km, but it is absurd to think of doing 30K km with the same oil, especially with an engine that has two turbos and more than 400HP. This way it is easier to have problems with the turbos or other engine components, i don't know why BMW recommends this mileage. Most owners change it at 8K km (me included) or at most 10K km. Three oil changes in 64K km are more than right for BMW but are few for those who care about their engine.

Seriously?!?! Every TWO years or 30k km?? That’s more than 2x years and 1.5x mileage intervals compared to the US intervals. That’s crazy. BMW “free” service intervals are ridiculous. They were already recommending shorter mileage OCIs for synthetic oils before switching to free maintenance so it wasn’t due to the use of synthetic motor oil that drove the intervals to what BMW uses with free maintenance. It’s about cutting costs with the use of free maintenance. Basically, what intervals can get the cars thru the free maintenance and warranty periods with the least costs.

[camF80]

Originally Posted by MineralWhiteF80

typically a whining noise at a certain speed range while on throttle is mostly commonly the rear differential. You can get the noise to audibly change a little bit with applying more or less throttle input, but overall if the noise is mainly speed related and not gear related, then it's good to think about the diff.

The F8x differentials are not imune to these whines and most whine more as they simply age. A torn differential bushing can contribute to the whine volume but still not show any 'bad diff bushing' symptoms yet. At 47k miles on the clock, you are within the window of possible bushing issues HOWEVER, I see you have a 2018 model year, and I believe they changed to the poly diff bushing (instead of fluid filled) in 2018 to correct this diff bushing noise problem. You can look at your diff bushing to confirm if you have the old version or the countermeasured newer style.

In 2016-ish, there was even a bulletin that BMW put out on F8x cars having loud diff noises where they recommended diff replacement but they also believed it only a select VIN range (production date) was affected and you would not be included in that.

Hi, sorry I'm really late to this. Something I noticed the other day which continues to make me suspicious about the DCT is when I'm looking forward in the drivers seat, I can hear it clearly from my right ear, like when you get random tinnitus ringing. When I look 90 degrees right directly out of the passenger side window, I can hear it totally out of my left ear. I would assume if its coming from the diff I would continue to hear it out of my right ear wouldn't I? But when I change directions where I look, its like wearing headphones with 1 side turned off. It's also getting louder, I used to could drown it out with music at 40% volume and exhaust noise, now its starting to overpower that. I've also since noticed theres a variety of other whistling and whirling noises that the car just makes all the time, maybe they were always there and I just didn't notice them until the other whine got louder.

I recently drove a friends Stage 1 car that has 15k more miles on it than my stock one, and his car is dead silent in the drivetrain, no whistling or whining anywhere. My car on shiftlogic 2 also feels way thunkier going into gear than his does. His shifts very smooth and mine tends to thunk into gear over 4k.

Let me know what you think, sorry for the late reply.

[camF80]

Originally Posted by M3SQRD

Have you checked to hear whether the sound changes or stays the same in different gears? How many miles does your car have? MT or DCT?

In my experience, what gear I'm in doesn't matter. The whine only appears in the speed ranges mentioned in my OP and being on throttle. As soon as I'm off throttle the whine goes away. However, the whine from my videos is much louder IRL and has gotten louder even since those videos. I used to could drown them out with exhaust noise and music, now its overpowering that with a sound similar to random tinnitus ringing in my right ear.

[camF80]

Originally Posted by M3SQRD

Yours is a tough one to diagnose. If it makes the noise in any gear and only between a specific speed range but goes away when DCT is put into neural would point to the trans and possibly the engine, not the diff. But if it was the engine, then the noise would be at different speed ranges for different gears (i.e., engine rpm range, not road speed range). As for what part of the DCT, it’s to isolate because it only makes the noise between a certain speed range. It’s definitely a resonance of some kind due to it only happening within a specific speed range. It’s like not the tires/wheels because the noise goes away when the DCT is in neutral. 50k km is well within the DCT fluid life/change interval. Where does the sound appear to come from - in front you, under/beside you or behind you?

Hi, sorry for the late reply to this. Sounds like he is experiencing the same thing I am as documented in my OP. It's ONLY in speed ranged of 45-55mph, give or take, and 70-80mph, give or take. With around the middle of the speed range being the very loudest in volume. If you give a listen to the video I'll link, you can hear the whine come on the loudest right as I cross 74mph. In real life, the tone is much louder, and seems to be getting louder. It only happens when I'm on throttle. If I let off the throttle or switch into neutral, the whine goes away immediately.

Driving a friends car, I noticed his car also shifts much smoother than mine, both being in shiftlogic 2. His car is BM3 stage 1 tuned, and mine is stock power wise. Both of us run the GTS DCT flash. His car shifts very smoothly both in auto and paddle mode. My car seems to shift very hard in paddle mode over 4k, thunking into gears, where as his doesn't.

Let me know what you think, thanks
https://www.youtube.com/shorts/o0podPtOZho

[M3SQRD]

As for which ear you hear the sound could depend on what’s getting excited by the speed range frequencies. For example, it could still be the diff if something else close to the driveshaft, such as a heat shield, has a resonance(s) in the frequencies the diff is creating. Does the noise completely go away when you put the DCT in N? If it sounds the same in any gear (not rpm dependent) and with/without throttle and in/out of gear then it’s probably the diff or tires exciting something in the center of the car at those speed ranges. Have you had any work done under the car recently (or at the time you first head the noise)?

Lol - we were writing responses at the same time

It’s likely not your DCT although the differences in Auto and Manual mode performance between your and your friend’s cars is interesting. Unfortunately, I’ve exclusively used DCT Manual and setting 3 modes. Mine shifts soothly in any gear except under full throttle where you get the torque kick at the gear upshift. Have you checked your tires to see if there’s any odd wear patterns on a tire?

[camF80]

Originally Posted by M3SQRD

As for which ear you hear the sound could depend on what’s getting excited by the speed range frequencies. For example, it could still be the diff if something else close to the driveshaft, such as a heat shield, has a resonance(s) in the frequencies the diff is creating. Does the noise completely go away when you put the DCT in N? If it sounds the same in any gear (not rpm dependent) and with/without throttle and in/out of gear then it’s probably the diff or tires exciting something in the center of the car at those speed ranges. Have you had any work done under the car recently (or at the time you first head the noise)?

Lol - we were writing responses at the same time

It’s likely not your DCT although the differences in Auto and Manual mode performance between your and your friend’s cars is interesting. Unfortunately, I’ve exclusively used DCT Manual and setting 3 modes. Mine shifts soothly in any gear except under full throttle where you get the torque kick at the gear upshift. Have you checked your tires to see if there’s any odd wear patterns on a tire?

Makes sense regarding the resonance part and which ear I'm hearing. Hard to turn off that feeling though when it feels like a pair of headphones with one side turned off just switching sides. Yes, if I'm not on in gear and on throttle, the noise completely vanishes. Also, the amount of throttle does not impact the volume/tone of the whine. The more throttle I give it, the quicker I just get out of the resonance range. As far as work done to the car, not that I know of. I bought the car in November with 46k on it and am at just over 48k now.

Now, don't get me wrong I don't drive the car like a Prius, I have a good time in it, but I'm also not beating the absolute snot out of it either. Even when driving it hard, the car has plenty enough power where I rarely feel the need to shift over 5k when doing any sort of road fun. 3-4k and I can more than keep up with my friends on non-racetracks, however I do not plan to track the car at this time. All of that to say I do not think my driving would have created this problem either.

I have not checked the tires, but I will later this afternoon, thanks for the suggestion.