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Wheel Speed Calibration


lostsoul

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I must be missing something ....  according to "help" to calibrate ..... # of Teeth (26) / wheel diameter (0.61m including tyre ) x 31.83 = 1,334.1 ... to me this can't be right as I am getting a speed reading in the "thousands" kph with a calibration of 260 ??????

Car is a z32 300zx with the G4+ Thunder fitted ... factory wheel sensors.

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The calibration number of ~1300 should be correct for your setup.  A bigger calibration number will give you a lower displayed speed.  I suspect MagicMike's number might be from a gearbox sensor, not a ABS sensor?

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Thanks for clearing that up. What through me was the help section stating that the values would typically be 170 - 280 ... since my wheel sizes are typical and the ABS sensor wheels are factory ... well anyway you get the picture.

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Any number of frequency dividers can be used to reduce ABS or high frequency gearbox sensors down to sub 500Hz levels. Dakota digital make a simple to use box that does this, but you can also build your own out of about $15 of parts from jaycar using a 4024 frequency divider chip (I have one on a modern honda gearbox reducing it by /16). If you put this divider between the point you splice into the wire and the ecu, you can leave the ABS in tact.

FYI I also found in testing that the DI inputs can accept slightly higher than 500Hz - about 1300Hz (@12v) they go from reading ok to just reading 0hz until a few seconds after you bring the frequency back down. I wouldn't recommend using them like this though on purpose as i'm sure there is a reason Link dont recommend over 500Hz, but if you hit 501Hz briefly it will still register correctly.

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