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Guessed what, did a drive with the tech said he didn’t hear anything abnormal, trying to throw me the normal battery sound. Ima just let the car sit for another couple hours and test drive again.Having a appointment tmr. Since it chill here in nyc this week. Ima see what they gonna do about it tmr. Ima keep y’all updated.
You have done way more research than me on this, and the theory discussed in your post seems to make sense. However, the sound stops when there is even the slightest increase of power to the wheels while traveling in a straight line, so I wonder if the reason you stop hearing the sound during a hard right turn may also be attributed to the increase in power required to maintain a constant speed during the turn. I may have missed you addressing this thought previously.I'm somewhat doubtful it's electrical in origin (EMI or otherwise), I think it's physical. At least in my car, taking a hard right makes the noise go away during the turn. I can't see any way that mechanical loading caused by the right turn would cause an electrical noise go away. I already posted frequency spectrum graphs in previous posts of the noise directly from the source (front drive unit). It's certainly coming from that, I can't see how you'd learn anything from listening in other parts of the vehicle. I fear the only way you'd really learn what's going on is to actually take a noisy front drive unit apart, and even then the issue might not be obvious.
So I actually asked the Professor John D. Kelly from Webber Auto youtube what he thought of the issue. He's a university professor who specializes in drive-trains, including EVs. I gave him a breakdown of the issue and he was very responsive, but he only had a theory. What he said:
"
- The following is my opinion only; it may be totally inaccurate -
The only thing I can think of that might cause that noise is what appears to be a sacrificial grounding bearing inside the rotor shaft near the resolver.
This bearing has a black metal tab inserted into its center race to connect it to the drive unit housing. I believe this connection grounds the rotor shaft and prevents shaft currents in the main rotor bearings.
If this bearing started to fail, it could make a noise that would change with the rotational speed of the rotor (vehicle speed).
Although this noise would have no immediate impact on the longevity of the other bearings, over a long period of time, it may become an open circuit, allowing the other rotor bearings to pass the inducted shaft currents and possibly cause premature failure.
Attached is. photo of the bearing and tab from the rear motor, but the front motor has an identical setup.
View attachment 929215
The tab is not painted. It makes a spring-loaded electrical connection with the inside of the center race of the bearing.
"
Interesting theory, but only really stays a theory until someone can tear-down one of these noisy units to investigate.
I also asked another Tesla tear-down Youtuber, Phill from Ingineeix. He's also take apart lots of the electronics on the model 3/y including the drive-train. Regarding our issue, he said that Tesla changed the front motor design around late 2021 (the earliest cars on this thread with the noise) from a copper "squirrel cage" in the rotor to an aluminum one. I wonder if other things changed then too. He also said "
The lack of noise after a sustained right turn means the lubrication oil is sloshing to the left. That could be an important clue. The motor is on the right, so this would take extra oil away from the motor side and deposit it in the gearbox side.
"
I was surprised the oil was thin enough to slosh, he said "The oil is quite thin, it's designed to be very low drag to not impact efficiency."
Another interesting theory, could also explain why temp plays a role, colder oil will be thicker and less likely to coat problemed parts.
I can't speak for everyone, but my sound does not stop when power is applied to the wheels and going in a straight line.You have done way more research than me on this, and the theory discussed in your post seems to make sense. However, the sound stops when there is even the slightest increase of power to the wheels while traveling in a straight line, so I wonder if the reason you stop hearing the sound during a hard right turn may also be attributed to the increase in power required to maintain a constant speed during the turn. I may have missed you addressing this thought previously.
Oh mine doesn't go away with power increase, I can hear it from hard acceleration (up to when the front motors turn on, then it's hard to tell) down to hard regen. And it goes away during right turns regardless of power (increasing speed, decreasing, maintaining). And I don't mean is faint, it's truly silent (again listening with directly to the drive unit with a microphone). Also left hand turns have no effect on the sound. I was playing with this in a parking lot, counterclockwise turn (left) makes noise, then clockwise loop (right) no noise. Maybe I'll make a video.You have done way more research than me on this, and the theory discussed in your post seems to make sense. However, the sound stops when there is even the slightest increase of power to the wheels while traveling in a straight line, so I wonder if the reason you stop hearing the sound during a hard right turn may also be attributed to the increase in power required to maintain a constant speed during the turn. I may have missed you addressing this thought previously.
Thats only if you have a consistent never ending high pitched wineMine has two sounds and someone posted it on here. I put in the service request for them to check the perimeter penthouse seal in the rear motor and the front drive motor as well b/c that is a different sound. I fear that people are not going to have this solved. It is a pity too b/c I like the car but this sound is so annoying and frustrating that Tesla advisor says is normal. NO it is not!!
the thing is I dont think the speaker is loud enough to generate a noise like that at highway speedsThanks for the input. I think I will look into some of the apps and do some collection with one of those. I agree with your point that, even though no power may be going in/out of the front motor, electronically it is probably still doing something.
As mentioned before, I work as an engineer in R&D for a major supplier of electric powertrains for commercial vehicles, and I am somewhat familiar with the different topologies and control strategies. But I have not dug into these finer details of the Tesla dual motor setups yet -- like what exactly is happening with the front induction motor at steady-state highway speeds.
Last night, after I posted my update, I was thinking to myself, "You know, I described this earlier as a kind of a staticky noise, like a bad ground on a speaker.... what are the chances that it could ACTUALLY be coming from a speaker?" Like some kind of weird interference between HV power electronics and a speaker wire. It just hardly seems like the kind of noise that originates at the FDU, goes through the firewall, and into the cabin.
It looks like there were a bunch of issues with staticky speaker noise on earlier Teslas. Most of those were staticky even if the vehicle was parked, so maybe I'm just dreaming this up. I'm probably going to do some test driving this weekend and see if I can link it to a speaker, through "various methods" which I will share later. I don't like the idea of just dumping it on the SC again and ending up with another swapped FDU for no reason...
Thats exactly i live in toronto too, i went to the SC in vaughan, the tech insist they dont hear anything.Here is my experience:
- Bought the car in June 2022, new, 3LR. No noise until mid September (I live in Toronto, so by September the temperature starts to get around 60-50F).
- I have been hearing this noise consistently ever since (will see how it behaves this summer and if it does go away with warmer temps).
- When 'navigating to supercharger' the noise goes away at some point (I do hear a number of other noises from pre-conditioning, but not our ever-present drilling). As i understand, the car runs the motors on a 'less efficient' mode to generate heat while driving to warm up the battery. However, on normal drives, I can drive over 200km on highway and the noise will still be there, so the normal 'warming-up' of the car on regular driving doesn't make the noise go away for me.
- The noise starts almost every time when I cross the 65kph (40mph) mark (only exception is when Tesla tech is in the car). I can hear it even at higher speeds such as 120kph (75mph). It is intermittent in the sense that in the same drive it keeps going on and off while above 65kph but it is always there, regardless if I am coasting, accelerating, decelerating...
- When decelerating, somewhat quickly, I can hear the noise up until 50kph (30mph). It almost gets a bit louder as it nears 60-50kph, then it cuts-off sharp and the noise is completely gone below 50kph. It won't come back again until I am above 65kph (40mph).
- It has been almost impossible for me to replicate the noise when a Tesla tech is in the car. It only appeared once (out of the 4 times I went to North York SC) for a brief moment, and yet, very faint that even I had trouble hearing it. I suspect that when Tesla puts the car in Service Mode and we go for the drive, Service Mode may alter some behaviour of any of the car systems? I am not sure.
It is temperature for me it usually occurs for me below 60 degrees.if It is the front motor making the sound. That is weird, because the front motor doesn't engage unless the rear motor cannot provide enough power during throttle -- so the front motor kicks in with the added torque until the rear motor can once again handle the demand by itself.
And since I usually hear this at crusing speeds, that means -- again, if it IS the front motor -- that it would be creating the sound while not even in operation.
Edit: welp, i now see the more technical discussion about this topic above me. My fault for not reading!
i will just reiterate, it has something to do with temperature. I can say without a doubt, if it is not cold outside, I will not hear the sound. But in the wee mornings and just leaving the house, I can almost always depend on this sound. After work when I leave, and the day has warmed up (including my car), no sound whatsoever.
Which then makes my uninformed mind think -- battery? If the battery charges and runs optimally when it is warmed up, could these sounds be byproducts of a cold battery trying to stabilize?
Great news! You certainly put your time in trying to get this fixed. I would do some more tests but I bet you're new DU will be fine. I think if it was defective you would have heard it for sure. When we try really hard to hear/see/feel something, sometimes our brains can play tricks on us. Keep us posted.I got the car back with a new front drive unit. And guess what… the noise is gone (so far)
I drove only 250 km but the FDU is silent. I tried multiple speeds in the morning with a cold car : nothing !
However, I think I could hear it a fraction of second during a deceleration. It was way too short to know exactly where it came from or even if it was the same noise. Now I’m just worried that the noise may come back after a few thousand km…
Anyway, if it could remain like that, I would be the happiest.
Question to those who had a defective spare drive unit : did you hear the noise immediately after leaving the SC or did it take a few km before it appeared again ?