Quote:
Originally Posted by OkieSnuffBox
Noise, Vibration, Harshness
Essentially nearly all strut/shock tower bars are doing is raising the natural resonant frequency of the chassis so NVH is decreased.
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THAT makes perfect sense! I do a lot of hi-fi related stuff and two things I know well -- stiffening a speaker cabinet by bracing internally raises the fundamental resonant frequency of the cabinet to a higher pitch, where it is MUCH easier to kill with damping material.
Second, a more rigid tonearm (for a record turntable) accomplishes the same thing, but also provides a much better platform for the phono stylus, suspension and cartridge body to work against. I suspect that something similar is happening with the braced strut towers and the struts/springs using the GrimmSpeed or similar device. They work more efficiently because of the improved rigidity of the strut towers. The stiffness of the strut tower (braced by the two stock ones plus the GrimmSpeed) has to be enhanced to some degree because the three braces now form a triangle. That is the strongest, most rigid geometric shape.
The proof is in the pudding; I will get back with a report after I have a chance to actually drive with the darn thing in place. The rain has stopped so maybe later today.
Added: Another reason for trying to raise resonant frequencies is that higher frequencies decay more rapidly than low, which tend to carry further and through all kinds of materials. Think of the situation where your neighbor in an apartment building is playing music loudly, but all you hear is the bass coming through the wall. Everything else is muffled.