Thread: Any advice?
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Old Tue, January 13th, 2009, 07:05 PM
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Jackpine Jackpine is offline
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Originally Posted by Cajun View Post
Most local police will help you with this sort of thing if you just pull over and talk to them.

You could have someone pace you in a vehicle that you think is accurate. You can also time yourself between mile makers, if you're doing 60mph, it should take you exactly one minute between markers, then use Jack's formulas to calculate which way to tweak the computer. Neither is nearly as accurate as Jack's method, but they should get you close till you can take the road trip to really test it.
Especially if you want to verify that you're doing 70 in a School Zone!

Cajun is quite right on the 60 sec to do 1 mile at 60 mph. If you get that so it looks right, you'll probably be within +/- 1 mph of the real speed.

And, in case you've missed other posts on this - The truck's speedo will ALWAYS read 2 mph high if you "dial in" the Gryphon displayed speed to be dead accurate. At this speed though, the odometer will be accurate. You can think of this discrepancy as Ford's attempt to keep you from getting a ticket, since you think you are going 2 mph faster than you really are.

- Jack