Speedometer Adjustment

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Apr 1, 2019 | 05:03 PM

lawnspecialties

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Joined: Oct 2005

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From: Garner, NC

Speedometer Adjustment

Seems every Ford truck I've ever bought, the speedometer reads faster than the truck is going. I've even gone so far as to think Ford has been conspiring to end everyone's 3/36 warranties early. I know, just the conspiracy theorist in me.

But this new truck is the worst. My drive to work is 6.1 miles according to my 2013 F350. But the drive in my new truck is 6.8 miles. Driving 70 mph down the highway (I think), I am getting my doors blown off by little old ladies.

What's the cheapest way to fix this? Will that FORScan work?

Apr 1, 2019 | 05:07 PM

TeddyD

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Download a profession but free gps app in your phone and see what the speed says on the app in relation to your speedometer. Easy free way to check. I use GPS Commander or something like that.

Apr 2, 2019 | 12:00 PM

lawnspecialties

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Joined: Oct 2005

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From: Garner, NC

In addition to my speed being off, I don't like the fact my odometer is turning faster than it should. When my odometer says I have 100,000 miles, the truck would really have less than 90,000.

Apr 2, 2019 | 12:48 PM

TeddyD

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For sure. You don’t want your odometer to lie to you. If your speed while on cruise control at a constant high speed matches the gps app, you are fine. If it doesn’t match, then you need to make a correction. You can’t base the distance off of measuring the odometer from an older truck as it could be a little under and your new truck is a little over. Find the exact offset of your speedo and gonfrom there.

Apr 2, 2019 | 02:59 PM

Adam R

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I'm pretty sure all factory speedometers over report the actual speed to one degree or another. That way a defendant in court cannot blame their speeding ticket on Ford, Subaru or any other manufacturer.

One way to correct the speedometer is to put on a slightly larger tire of the correct diameter.

Apr 2, 2019 | 03:16 PM

Turbo Dog

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Joined: Sep 2012

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From: Laramie, WY

Quote:

Originally Posted by Adam R

When I was working for one of the big three auto companies we not only measured our speed and distance but that of our competitors. Every vehicle I ever tested was actually going 77 mph while indicating 80 mph...it was the same for every company. That was using regularly calibrated accurate and precise equipment.

I used a speedo calibrator on my 2013 F150, it was similar to a code reader but it allowed for changing tire sizes. Here are a couple examples:
Summit Racing Speedo calibrators

Apr 2, 2019 | 03:54 PM

cficare

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From: SEVA

Quote:

Originally Posted by Adam R

I'm pretty sure all factory speedometers over report the actual speed to one degree or another.

I was curious because my Garmin GPS says my motorcycle consistently displays a speed which is 10% higher than actual, but my F250's speedometer is spot on. If it is off, it's off by no more than 1/2 MPH.