Wheel of fortune noise at low speed from gearbox area

[JoeCool88]

When driving my 2018 i3 94A at low speed sometimes a flap - flap noise, like this from a wheel of fortune, occurs. The noise is relatively silent and usually masked by the pedestrian protection sound generator and/or ventilation noise. With radio on you will never hear it. So I could imagine that a lot of i3 unnoticed have the same phenomenon. When rolling at speeds between 10 - 20 km/h I could provoke the noise by varying the torque of the transmission by the accelerator pedal. I removed the trunk floor cover (= engine bay top cover) and listened during driving, pretty sure the noise is coming from the differential area.
At speeds above about 30 km/h the noise disappears, but I couldn't tell if this is because of the high frequency it has at higher speed and/or the increasing other noises when driving at higher speeds. Somewhere in the web I found that a BMW specialist told to remove the drain plug of the gearbox (which should have a magnet) in such cases. If you find metallic particles on the plug you should replace the gearbox, if not "continue to drive". Removing the mag plug will be my next step.
Does anybody who maybe had the same phenomenon on his i3 know something about the origin of this flap-flap "wheel of fortune" noise? The design of the gearbox is very simple. So the plan is to do repair, if necessary, on my own.

 

[Anonymous]

First check underneath the car for any loose plastic panels or insulation, or anything caught in suspension or in body panel seams. Friend with similar noise (not on an i3) was ready to pull his hair out trying to find the cause. Finally took it in to a transmission shop, thinking it was failing and needed to be rebuilt. Up on the hoist, they found a piece of plastic wedged in the suspension. At specific speeds it vibrated/flapped against the floor panel in the air-flow, sounding like the playing cards we stuck in our bicycle spokes as kids.

 

[bdjuju]

Did you ever figure out what the problem was? I've got the same sort of noise on my '14 Rex w/115k mi. 'Wheel of Fortune noise' is a perfect way to describe it. It also sounds like a bad CV joint, but my boots look like they're in good shape & I haven't heard of anyone having problems with the driveshafts. I suppose its possible, and this point I'd welcome that, vs other options (traction motor, mounts AGAIN)

 

[MrL]

I am afraid I have somewhat of bad news. I experienced the same sort of noise. At first only under load going forward, but that changed to a constant thing and it got worse. Much worse!
It turns out it was the transmission / differential, better something inside it, that went bad. In the final stages my i3 would roll, even though it was in park, and lastly it would just give me a drivetrain error and no longer go into park. With that comes a host of other issues, like you can no longer open your charge flap, and if you had BMW or a body shop work on it and they were lazy they may not have reconnected the charge flap manual override cable - LOL.
Anyway, The cost of the differential - varies by i3 model but - is between $700 and $1200 ish, which is not too bad. Now to the bad news. The dealer said it's 22 hours of labor! Actually the whole dealer quote was $6500 to fix it. I ultimately got it fixed by an independent BMW mechanic who charged me $4700 out the door. In this repair they literally have to remove the entire rear end, drop the entire power train out of the car, separate the REX (if there is one) and then get to replacing the differential! Here is an important thing: while the power train is out of the car have the mechanic replace the camshaft position sensor and other otherwise inaccessible sensors on the REX! Just saying. You will save money that way! I asked my mechanic to look at any sensors that may need replacing because I had REX errors before (mainly overspeed shut down errors). This was the camshaft position sensor going bad and it is located between the rear firewall and the rex up on a ledge. You can get to it - it is possible to change it out later, but most shops will not do it or still charge you for the powertrain removal!!!!! For a sensor!!!! Trust me, I paid another $400 ish including the sensor because my mechanic didn't as I had asked.
Now the car is running again - strong and quiet.

Here are some pictures of the whole mess:
https://share.icloud.com/photos/0d6LW-TqUOpljZWZn4ddiXSsg

 

[Arm]

I am afraid I have somewhat of bad news. I experienced the same sort of noise. At first only under load going forward, but that changed to a constant thing and it got worse. Much worse!
It turns out it was the transmission / differential, better something inside it, that went bad. In the final stages my i3 would roll, even though it was in park, and lastly it would just give me a drivetrain error and no longer go into park. With that comes a host of other issues, like you can no longer open your charge flap, and if you had BMW or a body shop work on it and they were lazy they may not have reconnected the charge flap manual override cable - LOL.
Anyway, The cost of the differential - varies by i3 model but - is between $700 and $1200 ish, which is not too bad. Now to the bad news. The dealer said it's 22 hours of labor! Actually the whole dealer quote was $6500 to fix it. I ultimately got it fixed by an independent BMW mechanic who charged me $4700 out the door. In this repair they literally have to remove the entire rear end, drop the entire power train out of the car, separate the REX (if there is one) and then get to replacing the differential! Here is an important thing: while the power train is out of the car have the mechanic replace the camshaft position sensor and other otherwise inaccessible sensors on the REX! Just saying. You will save money that way! I asked my mechanic to look at any sensors that may need replacing because I had REX errors before (mainly overspeed shut down errors). This was the camshaft position sensor going bad and it is located between the rear firewall and the rex up on a ledge. You can get to it - it is possible to change it out later, but most shops will not do it or still charge you for the powertrain removal!!!!! For a sensor!!!! Trust me, I paid another $400 ish including the sensor because my mechanic didn't as I had asked.
Now the car is running again - strong and quiet.

Here are some pictures of the whole mess:
https://share.icloud.com/photos/0d6LW-TqUOpljZWZn4ddiXSsg

What year is your car?