Gearbox whining, chirping sound?

[jameskk]

If it’s a normal sound of the inverter, I’m curious at why it is so pronounced on the Cybertruck and not audible on any other Tesla I’ve driven?

Additionally, if it is a normal sound than it seems that they should be able to make it quite like it is on other Tesla’s.

According to the tech who drove my vehicle, other Tesla motors make this noise... some Model S models, depending on the inverter.

The sound can be annoying at times, but overall I love the futuristic sound of the Cyber's motors.

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[RayzorBEV]

This is from my CT. The SC tech did 2 test rides and told me this was normal noise from the inverter.

I've owned 5 Teslas, 3 Rivians, 1 Polestar-2, 1 Jeep Grand Cherokee Summit Reserve 4xe, all have inverters in them and I have never heard this Robo-cricket noise before ? until now.

 

[HaulingAss]

I've owned 5 Teslas, 3 Rivians, 1 Polestar-2, 1 Jeep Grand Cherokee Summit Reserve 4xe, all have inverters in them and I have never heard this Robo-cricket noise before ? until now.

Anyone who says the chirping noise is the inverter is simply wrong. Inverters can make a whining or humming noise, but they do not make the chirping sound that is a characteristic on all Cybertrucks. The chirping noise is caused by harmonic interactions of the gears in the gear reduction unit. These are the same kinds of sounds I've been hearing for over 50 years in heavy duty truck transmissions (manual shift only). The Cybertruck's gear reduction unit is like a one-speed manual transmission that cannot select any other gears. The sound can be more noticeable in an electric vehicle for two reasons:

1) It doesn't have engine sounds to mask it, every little sound stands out.

2) The Cybertruck engineering is very weight conscious, the gear cases are much thinner/lighter than the gear cases of an old school manual truck transmission. This allows the sounds made by the gears inside to transmit outside more easily.

I think the real "problem" here has more to do with the fact that most younger motorists have little experience driving trucks with heavy-duty manual truck transmissions, they grew up driving cars and trucks that did the shifting for them.

On the heavier duty class of trucks with manual transmissions, I could always hear this gear chirping coming through the gear cases, even over the loud engine sounds in the cab. No one used to complain about the gear sound, it's 100% normal. I've always liked it personally, because it was a characterisitic of a truck with a beefy gear box with a high GVWR (could handle heavy loads).

No Tesla has ever been made with such a strong gear reduction unit, nor one that had such a high reduction ratio. For example, the gear reduction ratio of the S&X are in the range of 8-9:1 while the Cybertruck is 15:1. In heavy duty manual truck transmissions, the chirping noises would become less apparent as you shifted up into higher gears, usually pretty minimal by third or fourth gear on most trucks. The Cybertruck's higher amount of gear reduction, combined with the beefier gears, makes the gear harmonics louder, just like in any truck with a manual transmission, the higher the load capacity, and the more torque multiplication there is, the heavier duty the gears become.

Similar sounds are present in the manual transmission of a legacy Honda Civic, although the gears are so small you will probably not be able to hear the sounds over all the other engine and road noises.

It rubs me the wrong way when used car dealers list Tesla's as having an "Automatic Transmission". It's false. There is no Automatic transmission, it's a manual one speed transmission without even a reverse gear. People are really slow to understand electric cars, including the younger generations, many of whom have never driven a heavy-duty manual transmission. The lack of the need to shift does not make the transmission "Automatic". There is nothing automatic about the single speed transmissions in all Tesla, they just don't need multiple gear ratios to overcome the natural weaknesses of all ICE engines, lack of a flat torque curve all the way down to 0 rpm, and the inability to spin much faster than 6,000 rpms (excluding high-performance racing engines). Electric motors can easily spin up to 18,000 rpms, some even higher.

Embrace the harmonics of those big, heavy-duty gear faces! Or drive a different vehicle, one that has a lighter-duty transmission or an automatic, like the car you probably learned to drive in. But please don't complain about the same sounds manual transmission truck owners have embraced as normal for over a century. Tesla wants this drivetrain to last 500,000 to a million miles, even when used as a truck.

Chirp, chirp!

 

[trentsize]

I think you're hearing pulse oscillation of motor power. I'm not sure, since there are other things that can make noises like that.

There's a weird physics function that adding power and coasting is more efficient than constant power for many types of motors. So the most efficient motor power curves is for it to apply power in short, single spin bursts based on the requirements of the driving conditions. If it's oscillating this in a frequency of human hearing (20-10,000 times a second), you'll hear it as a repeating tone.

-Crissa

I don’t think anyone else pointed this out here, but forcing the front motor to run full time on AWD seems to make the pulsating “cricket” noise turn in to a constant sound with the same frequency. Someone can try this with “slippery surface” or an off-road mode. I’m thinking people in colder weather are hearing it more pronounced than others too.

 

[igs]

Embrace the harmonics of those big, heavy-duty gear faces!

That's exactly what the sound is. I don't know why people keep saying it's the motor, this forum has so much FUD.

 

[OldDirtyRobot]

better audio of the noise

 

[Da_yo]

That cricket sound is not normal, none of my Teslas make that noise including my CT.

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