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Oops. Posted by Justin VanAbrahams [Email] (#32) [Profile/Gallery] (more from Justin VanAbrahams) on Tue, 29 Mar 2016 11:23:35 In Reply to: Re: Replacing the Speedometer, Justin VanAbrahams [Profile/Gallery] , Tue, 29 Mar 2016 11:03:25 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Realized one glaring error - the VSS is 4x the ECM... the ECM is 3965ppm, so the VSS would be 15860ppm.
VSS = 9832 pulses per kilometer
9832 pulses per kilometer = 15860 pulses per mile
(For what it's worth, 4000ppm is a common configuration, so maybe this is that.)
At 60mph, one mile per minute, I should see 15860 pulses per minute or 264 pulses per second.
At 60mph, a 195/60-15 tire has a 24.21" height and a 76.0194" circumference. A 195/60-15 tire is at 833.47rpm (63360"/76.0194"), or 13.9 rotations per second. The tire rotation is tied to the ring gear.
So... how do I tie 13.9 tire rotations per second to 264 pulses per second? If it's a 4 pulse per rotation, I would have a ratio of 4.75:1 (speedo:ring).
Buuuuuuut... that does not agree with the drill speed test:
760rpm = 12.67 rotations per second = 240Hz
700rpm = 11.66 rotations per second = 221Hz
Neither are 189.4Hz.
30-50Hz seems like a big margin of error, but a LOT closer than when I forgot the 4x multiplier. ;) Possible what I actually had was:
189.4Hz / 4.75 ratio / 4 poles * 60 seconds = 598rpm on the drill?
I think I can buy my drill press is off by 100rpm.
posted by 12.195.130...
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