... comparable to the way a basketball "rings" when it bounces... To me this means relatively low, am I right... if so, could point to the axle structure.
- is there any 'directional info' in the sound, from all four 'wheels'??? (=rotate, move head, listen)
Resonances:
- In my 9ton RV there was a standing wave pattern: the chassis had two main steel beams where all was attached [====] ,this created at certain speed a standing soundvawe 2feet above both bars. If one positioned head just 'into' the vawe, the noise was annoying just in a critical cruising speed. The spot was just were driver had to sit. Moving head sideways dimmed the noise considerably.
- The rooftop antenna in some Peugeots used to sit on the edge of the windshield. On certain fog temp/conditions, it would start to 'sing'. Not big issue, but on long trips not nice.
- One vehicle had (sometimes) singing caliper sheet metal shields. On first RV issue, filling the [ -beams- ] got the sound down (this chassis low frequency noise 'rose' to irritating levels after my complete engine noise killer project, resulting absolute engine tranquility. Its big diesel, neigborhood menace, became soundless, u didn know it was idling). On the second, half inch tape in the mid of the antenna killed the vibration vawelenght. Third noise needed drillin a hole to attach a extra spring to cause tension to the caliper shield. Noise killed.
The pic below depicts the shield. One could guess that this metal 'pan' may have equal frequency characteristics compared to the basketball ring plus++ having a loudspeaker membrane. (Shield: See the lower blk arrow start point in the pic below.) Bending, drilling, welding, cuttin, spring load, etc will enhance its characteristics frequency and possibly kill all its vibrations. See my article on killing chassis noises at
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see pic at
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...maxima used to have two open roadnoise 'amplifier loudspeakers' here; easy to fill and roadnoises kill... see also/ rip out the rear wheel sound amplifiers:
see pic at
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Note that you will NOT get any help at stealerships, this is truly beyond of scope of any std maint guide's CAUTION signs... But pls tell me how it goes.