Nasty whine from under gearbox started

[M5Rick]

The thing that comes up is that manual downshifting into too low a gear may have a bearing (pun not intended) on the whining. If it's not the missing foam noise insulator mentioned before then too much stress is being put on the dct with these sudden change downs. A race car with straight cut gears, which produce a fair amount of whine, can take this abuse but not an M for a prolonged amount of time.With seven gears and reverse the bearings themselves may be smaller than say a 5 speed s/auto in the confines of the casing and I believe it is the shaft bearings crying enough.Worn clutches wouldn't make this noise.
Personally I don't take the settings above Sport and prefer to keep it mostly in full auto where it changes down at the correct time without suddenly skipping to a lower gear.

[Boosted M5]

My car sounds the same under load, I suspect it's related to the dct oil pump. If you type "dct transmission oil pump upgrade" in the search bar of Bimmerpost, sspkris talks about an oil pump upgrade and stating that failing bearings will make a whining noise coming from the transmission. Just a thought.

[technician117]

I have a 6 speed car and have the same noise so I doubt it's the DCT's fault. The noise got slightly more audible after installing a Rogue shifter. I did reinstall all of the insulation but the first bottom piece is tough to remove/install so I broke the plastic part of the seal. I doubt it's totally sealing right now. A replacement is surprisingly cheap, ~$25 so I'm going to order one and see if it helps.

I will listen more closely now that I've seen this thread, but I also think my noise goes away in 5th!

[Kar001]

Originally Posted by technician117

I have a 6 speed car and have the same noise so I doubt it's the DCT's fault. The noise got slightly more audible after installing a Rogue shifter. I did reinstall all of the insulation but the first bottom piece is tough to remove/install so I broke the plastic part of the seal. I doubt it's totally sealing right now. A replacement is surprisingly cheap, ~$25 so I'm going to order one and see if it helps.

I will listen more closely now that I've seen this thread, but I also think my noise goes away in 5th!

I also have a 6 speed car that developed a nasty whine in first - third after a hard day riding with some of the fellas. I changed trans and diff fluid 3k miles before the trip, checked fluid before the trip, and changed again once the noise started (3/4 of the trip before the noise started). Car is stock and while I pushed it hard it was nowhere near what my 135i gets on a track day. What did you end up coming up with?

[technician117]

Originally Posted by Kar001

I also have a 6 speed car that developed a nasty whine in first - third after a hard day riding with some of the fellas. I changed trans and diff fluid 3k miles before the trip, checked fluid before the trip, and changed again once the noise started (3/4 of the trip before the noise started). Car is stock and while I pushed it hard it was nowhere near what my 135i gets on a track day. What did you end up coming up with?

The noise I get is far from nasty. I just live with it and most days I don't even hear it. When it's pretty cold out is when I can hear it most. I changed the fluid once so far at 50k miles. I didn't have ISTA running at the time so I couldn't flush the cooler. I plan to change the fluid again soon now that I have ISTA and can cycle all of the fluid out. Already have 22k on the oil change. My SOP for manual trans cars is normally to change the fluid every 50k miles.

[Kar001]

Originally Posted by technician117

The noise I get is far from nasty. I just live with it and most days I don't even hear it. When it's pretty cold out is when I can hear it most. I changed the fluid once so far at 50k miles. I didn't have ISTA running at the time so I couldn't flush the cooler. I plan to change the fluid again soon now that I have ISTA and can cycle all of the fluid out. Already have 22k on the oil change. My SOP for manual trans cars is normally to change the fluid every 50k miles.

I think this is my problem....we will see once I talk to the dealer.

After it started making noise I changed diff fluid also and it was already dark after only 3k miles. Guess mine never got the updated differential.

[scipy]

Kar001 did you ever get to the bottom of this? Because last weekend I had my car mapped finally (to get rid of the CEL due to catless DP), on the first attempt of measuring power with a road dyno the clutch slipped in 4th (even though XHP was put on the DCT beforehand, it seems it was abused slightly by the previous owner). After that it behaved normally and I went for a "hard ride" on a mountain pass and after 1/4 of the climb it started making this NEW whine like a supercharger. It was never present before in any gear etc. Don't believe it's the motor since it doesn't happen in neutral when revving.. just under hard throttle/acceleration. Video taken as soon as it started occuring:

[Kar001]

Originally Posted by scipy

Kar001 did you ever get to the bottom of this? Because last weekend I had my car mapped finally (to get rid of the CEL due to catless DP), on the first attempt of measuring power with a road dyno the clutch slipped in 4th (even though XHP was put on the DCT beforehand, it seems it was abused slightly by the previous owner). After that it behaved normally and I went for a "hard ride" on a mountain pass and after 1/4 of the climb it started making this NEW whine like a supercharger. It was never present before in any gear etc. Don't believe it's the motor since it doesn't happen in neutral when revving.. just under hard throttle/acceleration. Video taken as soon as it started occuring:

No never got to the bottom of it, my car is a 6 speed manual though ;-) I have just been putting up with it. But that sounds like you have a boost leak. . .totally different than what I have been hearing.

[ozcanroy]

I have the same issue, where I can hear it in 4th, 6th and 7th, but 5th is quiet. . .

[M5Rick]

Originally Posted by ozcanroy

I have the same issue, where I can hear it in 4th, 6th and 7th, but 5th is quiet.

Sounds then like the g/box has nearly had it.

[Arwon]

The noise will be quieter or non-existent in 5th gear because that is the 1:1 ratio straight through the gearbox. Every other gear uses a lay shaft and it will be a gear mesh issue or a lay shaft bearing issue.

[dadcrisis]

Originally Posted by Kar001

No never got to the bottom of it, my car is a 6 speed manual though ;-) I have just been putting up with it. But that sounds like you have a boost leak. . .totally different than what I have been hearing.

Kar001 did you ever get to the bottom of this?