Whirring Noise on Regen Braking on 2015 Model S

[JeTFiN]

I have been recently having a whirring noise on regen braking on my 2015 Model S 85D. This noise only occurs when slowing down with regenerative braking and the noise disappears when braking or rolling in neutral or while accelerating/maintaining speed. Here is a link to a recording of the noise where I started at around 42 mph and let regen slow the car down to a slower speed. Recorder The whirring can be heard from around the rear right wheel from inside the cabin.

Some background:
I hit a pothole last week and noticed a light clunk in the suspension afterward. In looking up the issue, I found out many people had issues with the washers on the axle hubs so I removed, inspected, and retorqued them. Relevant: I suspect it is possible but unlikely I over torqued them as I was following the manual with a torque wrench, but later when removing them again for further inspection a notably larger torque was required to remove them. After around 20-30 miles I noticed the whirring noise mentioned before looking further in the suspension to diagnose both issues. I discovered the clunk was from a loose bushing on a control arm that I will be replacing tomorrow. It is possible that this noise comes from that, but it is hard to imagine such a noise only occurring on regenerative braking if that is the source.

Has anyone heard this noise before, only on regen braking, and if so, what was the resolution?

 

[JeTFiN]

Update: Upon some more driving, I believe this is an additional symptom of the worn bushing on the control arm I mentioned. When regen braking, the noise is not there until the "clunk" is heard, then the noise is there, as if the whirring is the individual poles in the motor resonating through the structure with a ~1 lb hammer (the hammer being the control arm). Fortunately I will know soon as the replacement part shows up tomorrow!

 

[philip295]

I have been recently having a whirring noise on regen braking on my 2015 Model S 85D. This noise only occurs when slowing down with regenerative braking and the noise disappears when braking or rolling in neutral or while accelerating/maintaining speed. Here is a link to a recording of the noise where I started at around 42 mph and let regen slow the car down to a slower speed. Recorder The whirring can be heard from around the rear right wheel from inside the cabin.

Some background:
I hit a pothole last week and noticed a light clunk in the suspension afterward. In looking up the issue, I found out many people had issues with the washers on the axle hubs so I removed, inspected, and retorqued them. Relevant: I suspect it is possible but unlikely I over torqued them as I was following the manual with a torque wrench, but later when removing them again for further inspection a notably larger torque was required to remove them. After around 20-30 miles I noticed the whirring noise mentioned before looking further in the suspension to diagnose both issues. I discovered the clunk was from a loose bushing on a control arm that I will be replacing tomorrow. It is possible that this noise comes from that, but it is hard to imagine such a noise only occurring on regenerative braking if that is the source.

Has anyone heard this noise before, only on regen braking, and if so, what was the resolution?

I have a 2014 85S. It had a new drive unit 5 years ago . Recently, I've heard a humming noise on regen, but only after a long journey and the drive unit is presumably hot. I wasn't sure if it was the motor or the tyres, as they are almost due for replacement.

 

[JeTFiN]

I have a 2014 85S. It had a new drive unit 5 years ago . Recently, I've heard a humming noise on regen, but only after a long journey and the drive unit is presumably hot. I wasn't sure if it was the motor or the tyres, as they are almost due for replacement.

I changed the tires yesterday morning to no effect or reduction in the noise. Upon changing the upper rear left control arm that definitely had a worn out bushing, the clunk is still there. Due to a combination of how the issues present and behave, my best guess is that the clunk and subsequent vibration during regen braking is a result of a broken motor mount. I am hoping the break is on the mount side rather than on the motor side. I will be placing the vehicle on a lift today to inspect it.

 

[JeTFiN]

It appears as though the issue is contained within the rear drive unit. To determine this, the vehicle was lifted on an alignment platform and power braked to identify the source of the noise. The source strongly appeared to be generated from within the drive unit. Has someone heard this noise and identified a cause?

 

[NewbyMaybe]

Original drivre unit? You need to check the speed sensor plug on the drive unit for contamination. There should only be oil on it. If there's coolant fluid also then you need a rebuild.