driveshaft vibration cause false knock
02-07-2006, 01:16 AM
#3
The only way to find out is swap it with another!
I guess it wouldn't but anytime a vibration is produced just the vibration will cause 2st, 3ed, or ever 4th harmonics of lesser magnitudes. Those could be in that range.
I don't know dude. With my tize size and rear end I calculated that my driveshaft would be rotating about 56.77 times a second. 80 MPH, tire diameter of 27 inches, standard rear end for M6. So any oscillation would be about 60 hertz right? Well multiply that by 2 3 4 ect to find the harmonics. Nothing about 6,400 hertz which is what the knock sensor is looking for.
Wheel Diameter is 27 inches. Circumerence is 2*pi*r so 84.82 inches
If going 80 MPH that is ( 5068800 inches / 1 hour ) or (1408 inches / 1 sec)
That is (16.6 rotations / 1 second)
The rear end is 3.42... so 16.6*3.42 is (56.77 rotations / 1 second)
One hertz is one oscillation per second. Therefore (56.77 r / 1 sec) --> ~60 Hertz It would take 10 harmonic series to even hit in the needed frequency. It would be way to faint. That is my 2 cents!!!!
I guess it wouldn't but anytime a vibration is produced just the vibration will cause 2st, 3ed, or ever 4th harmonics of lesser magnitudes. Those could be in that range.
I don't know dude. With my tize size and rear end I calculated that my driveshaft would be rotating about 56.77 times a second. 80 MPH, tire diameter of 27 inches, standard rear end for M6. So any oscillation would be about 60 hertz right? Well multiply that by 2 3 4 ect to find the harmonics. Nothing about 6,400 hertz which is what the knock sensor is looking for.
Wheel Diameter is 27 inches. Circumerence is 2*pi*r so 84.82 inches
If going 80 MPH that is ( 5068800 inches / 1 hour ) or (1408 inches / 1 sec)
That is (16.6 rotations / 1 second)
The rear end is 3.42... so 16.6*3.42 is (56.77 rotations / 1 second)
One hertz is one oscillation per second. Therefore (56.77 r / 1 sec) --> ~60 Hertz It would take 10 harmonic series to even hit in the needed frequency. It would be way to faint. That is my 2 cents!!!!
