Strong Noise when driving above 67mph

[CanuckS#69]

All of the above. The drive unit is the chunk of complexity inside the rear subframe once disconnected from the suspension. This includes the transmission (such as it is), electric motor, and inverter. The electric whine noise comes from the inverter, but I'm not certain whether the highway speed noise is coming from the motor or the inverter. The recent factory drive units apparently are a new revision, perhaps to combat this issue.

The design on the drive units is really quite interesting. The entire assembly can be dropped out of the car and replaced in about an hour, so replacement is cheaper than diagnosis with the take off part going back to the factory for analysis.

 

[Hans (Amsterdam)]

I my MS I can hear the hum too. It starts at around 75 MPH.
At a speed of 80 MPH we made a recording and a frequency analysis.
It appeared that the hum frequency matches the rotation speed of the electric motor (165 Herz - 9.900 revs/minute)
So it seems to be some kind of resonance that is initiated by the electric motor. Of course it can be just any part that is resonating.
Very hard to find out.

 

[Edward D]

At 9k miles, my 85 had a hum at highway speeds. I could tell it was power related, not a speed related because it was dependent on accelerator pressure alone. The SC replaced the drive unit. That solved the problem for about 5k miles. Now with 18k miles, I have the problem again. I hate to ask them to replace the drive unit again or the inverter, but the noise seems to be getting worse.

 

[Frankrb]

Third time back to SC with the hum issue. They are now installing a new drive unit as I write this.

Almost 20k miles, and car will be one year old on 8 Mar. From discussion with SC, hum comes from a very minor "imbalance" in the motor. Since my hum grew over time, it will be interesting to see if it comes back with miles and time on the new unit. SC says Tesla engineering is all over it and new drive assemblies are an updated design and improved mfg process. Certainly needs to be watched going forward. don't want to have to pay for one if car is out of warranty.

 

[brianman]

View attachment 39848

I forgot about this post when I made my videos. Notice the frequency that Hans found is 165.87 Hz.

Compare that with:

7. high pass filter 150 Hz, 48 dB
8. low pass filter 200 Hz, 48 dB

And yes, my drive unit was replaced after I had a Tesla tech from Fremont listen to what I was hearing.

 

[mknox]

Third time back to SC with the hum issue. They are now installing a new drive unit as I write this.

Almost 20k miles, and car will be one year old on 8 Mar. From discussion with SC, hum comes from a very minor "imbalance" in the motor. Since my hum grew over time, it will be interesting to see if it comes back with miles and time on the new unit. SC says Tesla engineering is all over it and new drive assemblies are an updated design and improved mfg process. Certainly needs to be watched going forward. don't want to have to pay for one if car is out of warranty.

Sounds like we drive about the same annual distance. My car hit 20,000 miles today, and I picked it up last March 9th. I had my drive train replaced for the noise issue sometime last summer/fall, but I don't buy the "imbalance" rationale. My noise would start as soon as the power meter went into the "orange" zone and go completely quiet as soon as the power fell to zero or went into the green re-gen zone. I could make the noise come and go at will just by modulating the accelerator pedal. I believe the noise is being generated in the inverter as it kinda sounds like a transformer hum (at least my noise did).

 

[403portside]

OP here...

I can also confirm that my SC mentioned imbalance and also that a new design is or has made it's way into the production process.

 

[mknox]

I can also confirm that my SC mentioned imbalance and also that a new design is or has made it's way into the production process.

Maybe there's more than one thing going on here. I read another post from someone who had their drive-train replaced to cure vibrations in the cabin (I think the pano roof was mentioned). That definitely sounds like it could be caused by an imbalance. Mine was most certainly an electrical sound, probably from the inverter. With the motor directly coupled to the wheels, any sound made from an imbalance wouldn't go away when you take your foot off the "gas" like mine did.

 

[Duckjybe]

Maybe there's more than one thing going on here. I read another post from someone who had their drive-train replaced to cure vibrations in the cabin (I think the pano roof was mentioned). That definitely sounds like it could be caused by an imbalance. Mine was most certainly an electrical sound, probably from the inverter. With the motor directly coupled to the wheels, any sound made from an imbalance wouldn't go away when you take your foot off the "gas" like mine did.

Mine seemed to be electrical in nature as well. Sound was coming from right rear where the inverter is and in addition I was getting a faint buzzing sound at low speeds (45km/h) with a similar amount of power output.

 

[DCinDC]

I've been following this thread closely for a couple of months. I noticed some sort of a hum soon after delivery (within 500 miles). Not knowing if this was normal or not, I continued on until a few other things were bothering me (taillight seal and voice commands in the DC area that went out randomly). I took it in to the Rockville Service Center after the TeslaRoadTrip left DC to get everything taken care of and sure enough I came home with a different drive unit. I'm sort of mixed on the whole experience. It's making different noises now (e.g., more clicks than before in stop and go) and it is a refurb. I know there's another thread convincing folks that refurbs are probably better because any problems have been fixed, but that's sort of hard to swallow not knowing how much wear and tear might have taken place on the motor before finding its home in my car....

 

[Sparky]

For about 4 months, I've had a very noticeable hum (or perhaps thrum?) that seems to come at about 70 mph and stay as long as the speed is above that. It sounded a bit stronger than the OP's video. Different road surfaces didn't seem to affect it.
I just had my annual service and mentioned the noise. The tech drove it, verified the the symptom and suggested the tire wear may be the cause. Wheel alignment and tire rotation were performed and although it's not as quiet as the S85 loaner, the noise is greatly attenuated. So, in my case it seems tire wear and road noise was the issue.

 

[mknox]

For about 4 months, I've had a very noticeable hum (or perhaps thrum?) that seems to come at about 70 mph and stay as long as the speed is above that. It sounded a bit stronger than the OP's video. Different road surfaces didn't seem to affect it.

When I had the issue, I could make the sound go completely away by modulating the accelerator and making the power meter go to zero. Whenever the power meter was above or below zero I'd get the noise you describe. I could turn it on and off like a switch with this technique. Try that out. If the noise is consistent at any power level (including zero), then it probably is tire noise.

 

[brianman]

When I had the issue, I could make the sound go completely away by modulating the accelerator and making the power meter go to zero. Whenever the power meter was above or below zero I'd get the noise you describe. I could turn it on and off like a switch with this technique. Try that out. If the noise is consistent at any power level (including zero), then it probably is tire noise.

+ 1

 

[AmpedRealtor]

When I had the issue, I could make the sound go completely away by modulating the accelerator and making the power meter go to zero. Whenever the power meter was above or below zero I'd get the noise you describe. I could turn it on and off like a switch with this technique. Try that out. If the noise is consistent at any power level (including zero), then it probably is tire noise.

+2

My service center confirmed this also. If there is noise at zero energy usage, it's likely not the drive unit but probably something else.

 

[commasign]

my motor hum story

My car developed the motor hum rather abruptly after about 12,000 miles. It was silent below 60mph, subtle to about 65mph, then just plain unpleasant at every speed above that. At first I thought maybe it was always there and I just didn't realize it before, but all my passengers noticed it without me even mentioning it. So I sent audio recordings (iphone voice memo recorder placed on the floor of the rear seat area) to my service center and they quickly arranged for service. At service, they performed a "grounding procedure" and returned the car back to me. Unfortunately, it did nothing for the problem. So I did another audio recording, this time from ear level by the window of the left rear passenger.

Audio file here: Motor Noise Bad

This is at 75mph. Notice that the hum is louder than the music which is at moderate volume.

So discussed with service center and they decided to just replace the drive train. Just got the car back yesterday and the hum is gone.

Here is a recording from the same position also at 75mph. All you here now is the wind and road noise.

Audio file here: No Noise