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#61
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#62
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70 is about 103 ft/sec out tires are 5.7' circumference so 103/5.7=18.07 Hz at 70. 18*4.1=73.8 Hz aka 73.8*60=4428 RPM. That's definitely fast enough to be a problem with a small weight off balance.
I'm a little concerned about the possibility of under load causing an issue but that would be very similar to my theory of my under braking causing vibration. Do you get UFO noises when backing up?
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2011 E70 • N55 (me) 2012 E70 • N63 (wife) |
#63
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#64
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Driveshaft shake should be about 74hz on the vibration app but I don't know if it goes that high.
Use this app or similar to get an audio reading:. https://apps.apple.com/us/app/fft/id298840058
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2011 E70 • N55 (me) 2012 E70 • N63 (wife) |
#65
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As you have it disconnected, move the u-joint through is movement. There was the slightest notch when it got to one point. I MEAN SLIGHT! You could barely feel it but you will notice it.
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Digital Competition Systems The older I get... The faster I was... No Fear |
#66
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I'll try this other. Thanks! |
#67
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I had it apart when I replaced the CSB. I moved it though all motions, full range. It felt smooth.
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#68
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UFO sound comes from differential. Mostly noticable in reverse.
My bearing was silent for years but the suspect in my wobble/shimmy. I will know soon just swapped alternator and ready to test drive.
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2011 E70 • N55 (me) 2012 E70 • N63 (wife) |
#69
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That's good to know. Definitely no UFO noises.
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#70
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Here is an example from the FFT program. You can drag out a cursor to figure out exactly where the Spike is. You can also change the ex and Y axis so you can zoom in on a particular frequency range.
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2011 E70 • N55 (me) 2012 E70 • N63 (wife) |
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