MG4 SR rear axle noise

[otto]

Fortunately for some of us, we're not all the same when it comes to this buzzing noise linked to resonance at the rear of the vehicle.

may you use spectrum analysis(like spectroid)) app to show the frequencies distribution?

the acoustic problem is the symptom. The cause is mechanical

in my case the resonance is on 40 Hz and the cause is acoustic properties of connection(hole, pipe) inside space to outside(Helmholtz resonance)

 

[otto]

In my opinion that noise is present on ALL MG4s, but most people don't hear it, because it's a very low frequency. For those who hear it, however, it's very annoying. It does it at low speed on ruined roads

It's a headache noise and doesn't depend on speed

 

[agy]

I have news

Tried 4 car in dealer. All MG4 have the same defect
Focus is into rear part with brake rigenerativa system

 

[otto]

I have news

Tried 4 car in dealer. All MG4 have the same defect
Focus is into rear part with brake rigenerativa system

the noise also appears while accelerating or constant speed. regenerative system doesn't work in such cases

 

[agy]

Yes
When you are stopping at 1 kmh you can hear esclusion of rigenerativa brake and the sound vibration off

 

[otto]

in my case the resonance may disappear at any speed. The point is that the resonance may appear and disappear at any speed. this means that it is excited by outside noise - aerodynamic vortices or suspension vibrations

 

[adri78]

may you use spectrum analysis(like spectroid)) app to show the frequencies distribution?

in my case the resonance is on 40 Hz and the cause is acoustic properties of connection(hole, pipe) inside space to outside(Helmholtz resonance)

Interesting, and any ideas on how to fix it? Where are these connections located? If we found out, maybe by putting some sound-absorbing material the problem would be alleviated.

 

[otto]

Interesting, and any ideas on how to fix it? Where are these connections located? If we found out, maybe by putting some sound-absorbing material the problem would be alleviated.

need to find out where resonating chamber(s) are. or try to close all the holes in car body structure.
I don't know where the resonance occurs