Quote:
Originally Posted by Frank Reiner
A fault, that is the source of the vibration, could be in either the driveline (u-joint, center bearing, centering bushings, etc.), or in an axle shaft (bent shaft, bad CV-joint, loose splines). The other element, be it the axle shaft or the driveline, then may be vibrating in sympathy, at the ratio of the final drive - 3.07:1. The element which is at fault is the driver of the vibration, and the other element is being driven. The use of the word "contrariwise" was to indicate that each of the elements can be either driver or driven.
[Just as a curiosity, a 3.07 final drive has tooth counts of 15 & 46.]
The frequencies that have been observed are way below the first order (natural) resonant frequency of any of the driveline components, let alone the frequencies of 2nd or 3rd order harmonics.
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Sorry, not understanding how the sympathetic vibration could be so high a magnitude compared to the primary if it was something past the differential. It’s typical to pick up that ~14Hz vibration on any vehicle, not just this one. I had used this vibration sensing app on other vehicles when tracing wheel-reared vibrations.
I get the driver or driven aspect now, thanks for that. It just seems like the relative magnitudes would be the indicator.
It could be that there is play in the diff, a beating someplace, the driveshaft, the one iffy tire… whatever. Question now is how to isolate and move stuff. I have a lift that puts the car 20”+ up in the air at the bottom of the tires. It’s a nice height for diy without a pro lift, the downside is to get the height it is roll-on, so I need to jack the rear on the lift somehow.
Thank you for your explanations!