Quote:
Originally Posted by R.Diesel
The fundamental looks to be below 10hz with 2nd and 3rd order harmonics occurring around 14 and 42 hz respectively. Provided that these measurements are accurate they are too low to be either tire or driveshaft related. I believe you are dealing with an aggregated suspension harmonic issue due to excessive play. Id check all joints for tightness and double check alignment.
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The tires are 195/65-15, and do 829 revolutions per mile. This at 60MPH, it’s one mile per minute, or 829 revolutions / 60s… thus 13.8Hz. 14Hz x 3 = 42.
So I’m not seeing how 14 and 42 become the 2nd and 3rd harmonic, but that’s just me and my cursory math.
The 34lb roadforce tire, though on the front axle and not causing steeering issues or wobble in the steering wheel, could be in play, as could anything else I guess…
It just seemed obvious to me that if a tire vibrated once per revolution, and a driveshaft spun three times per tire revolution, that the math works out…. And was a pointer.
Everything feels tight which is also what confuses me. No funny play or movement anywhere….