Molande ljud från hjullager eller vad?

[LongIsland]

Min 70D som har gått 32500 mil nu fick ett irriterande missljud som jag märkte när sommardäcken åkte på i våras. Jag tog för givet att det var det ena bakdäcket som lagats efter att det suttit en skruv i det. Bakdäcken (275/35-21") byttes för ett par veckor sedan, men oljudet försvann inte. Tänkte att det måste vara de nya framdäcken som inte var bra och testade med att sätta dit mina dubbfria vinterdäck och körde en runda ... Exakt samma ljud. Funderar på om det kan vara ett hjullager, jag hör dock ingen skillnad på ljudet om jag svänger kraftigt. Enda gången ljudet ökar är om jag släpper "gasen" och motorbromsar. Ljudet börjar höras i 35-40 och följer hjulens hastighet så att säga. Kom på nu att jag inte har testat att lägga i friläget i 70-80 km/h och se hur det låter. Om det är något i kraftöverföringen så bör ljudet försvinna när bilen rullar i neutralläge .

Jag filmade hastighetsmätaren medan jag körde för att dokumentera ljudet vid olika hastigheter och skickade in filmerna i ChatGPT som spottade ut detta (och det var väl ungefär vad man kunde misstänka).

Tesla Model S 70D noise analysis

Date: 2026-08-28

Method
- The original `Archive.zip` attachment was left unchanged.
- All analysis was done on extracted copies of `IMG_1975.MOV`, `IMG_2088.MOV`, `IMG_2089.MOV`, `IMG_2090.MOV`, and `IMG_2091.MOV`.
- Speed references were read from visible speedometer frames in the videos.
- Audio was extracted from the copied MOV files and analyzed for recurring low-frequency peaks.

Speed references used
- `IMG_1975`: about 101, 107, 111, 118, 107 km/h
- `IMG_2088`: about 50 km/h
- `IMG_2089`: about 80 km/h
- `IMG_2090`: about 44, 50, 70, 90, 85 km/h
- `IMG_2091`: about 28 and 30 km/h

Main findings
- The noise is clearly road-speed dependent across the usable clips.
- The audio repeatedly shows two hum bands that rise with speed: roughly 20-50 Hz and 45-90 Hz over the 50-118 km/h range.
- Across the sampled clips, these bands scale at about 0.386 Hz per km/h and 0.658 Hz per km/h.
- Using an approximate front-wheel circumference of 2.214 m, those slopes correspond to about 3.1x and 5.2x wheel rotational frequency.
- The first clip, `IMG_1975`, was recorded with the winter tires. It contains the same general speed-dependent hum at 98-120 km/h.
- The low-speed clip `IMG_2091` includes modest side-to-side steering on a small road. No clear sound change is audible there, although the low speed and mild loading make it a weak wheel-bearing test.
- The owner reports that the noise becomes distinctly more pronounced only when the accelerator is fully released from higher speed, during maximum regenerative braking. The videos do not expose pedal position clearly enough to verify or refute this observation from audio alone.

Assessment
- Most likely: drivetrain under regenerative torque, especially a drive-unit reduction gear/differential or its bearings; medium confidence.
- Still plausible: a front wheel bearing; low-to-medium confidence. A stronger, sustained left/right load test at road speed would be needed to distinguish sides.
- Less likely: tire tread or tire construction; medium-to-high confidence against, assuming the winter tires were fitted on all four wheels. Reusing the same wheels would not exclude a damaged rim or wheel-related resonance.
- Less likely: rear tires specifically; high confidence against, because new rear 21-inch tires did not change the noise.

Why
- Rear-tire replacement made no difference, and the winter-tire clip has the same basic noise, which weakens a tire-only explanation.
- A wheel bearing normally responds mainly to road speed and side loading; no audible response to the available low-speed steering test weakens, but does not eliminate, that explanation.
- A repeatable increase specifically on full lift-off is a torque-direction clue. In a dual-motor Model S it is more consistent with a drive-unit, reduction-gear, differential, or related bearing issue during regenerative braking than with tire tread noise.
- The frequency tracks road speed because every component from the wheel through the final-drive gears is tied to wheel speed. Frequency tracking by itself therefore cannot separate tire, wheel bearing, and final drive.

Best next diagnostic step
- Have a Tesla-capable workshop reproduce the sound at the same speed in three conditions: light propulsion, zero pedal input with regeneration, and neutral coast. This should be done only in a safe controlled road-test setting.
- If the sound rises in regenerative braking and drops immediately in neutral coast, investigate both drive units' reduction gears/differentials and drive-unit bearings before replacing tires or wheel bearings.
- If it is unchanged in neutral and follows road speed only, test front wheel bearings with sustained left/right loading at speed and inspect the front wheels/rims and tires.

[manneson]

Impending motorras.

[tor-ake]

Hjälper inte att lägga i neutralläge, reduktionsväxeln och motorns rotor snurrar ändå.
Lyft upp bilen och snurra på hjulen för hand, ett i taget och lyssna.