Recalibrating speedo
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Recalibrating speedo
Hey guys, I lifted my truck and put bigger tires on it a while ago and I need to calibrate my speedo. Anyway I searched and found out how to do it here:
HOW TO RECALIBRATE THE SPEEDOMETER ON 92-96 FORD F-SERIES AND BRONCO .: Articles
I have two questions, what code do I want for 285/70 R17's? Also how do I exactly ground the wire it's talking about? And does someone have a pic so I get the right one?
Thanks.
HOW TO RECALIBRATE THE SPEEDOMETER ON 92-96 FORD F-SERIES AND BRONCO .: Articles
I have two questions, what code do I want for 285/70 R17's? Also how do I exactly ground the wire it's talking about? And does someone have a pic so I get the right one?
Thanks.
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From: southwest michigan
If you want to change the constant, find the single-wire connector (usually marked PSOM) under the glovebox and ground the LightBlue/Yellow wire (early '92 models use a Bk/Or wire)
Mine was labled so it was hard to miss. The best thing to do is go to tire racks website and look up your exact tire. there it will have the rev's per mile of that tire.
Once you know that:
RevsperMile x ToneRingTeeth / 8000
If you have a f150 with an 8.8 rear it's 108
the 10.25 sterlings have 120 teeth.
so if you had a tire that had 655 revs per mile and an 8.8 rear: 655x108/8000=8.84
Mine was labled so it was hard to miss. The best thing to do is go to tire racks website and look up your exact tire. there it will have the rev's per mile of that tire.
Once you know that:
RevsperMile x ToneRingTeeth / 8000
If you have a f150 with an 8.8 rear it's 108
the 10.25 sterlings have 120 teeth.
so if you had a tire that had 655 revs per mile and an 8.8 rear: 655x108/8000=8.84
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From: southwest michigan
Here is a pic I just took. I was kneeling on the ground on the passenger side of the truck (to help explain where this is). Sorry for the rough picture, it was my first time using a 7d, and I had the wrong lense.
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From: southwest michigan
If you want a rough Idea of what number to run...
RevsperMile = 20168.11439/TireHeight (in inches)
285/70 R17 is 32.70866141732284" in diameter.
so that's 616.5985863 rev's per mile
RevsperMile x ToneRingTeeth / 8000
616.5986 x 108 =
8.324 would be your conversion factor.
RevsperMile = 20168.11439/TireHeight (in inches)
285/70 R17 is 32.70866141732284" in diameter.
so that's 616.5985863 rev's per mile
RevsperMile x ToneRingTeeth / 8000
616.5986 x 108 =
8.324 would be your conversion factor.
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glad you got it done. Have you got to drive the truck after getting it changed? What do you think of how the truck runs? I noticed a big difference in how the truck managed shifting. a really big improvement for sure.
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Yeah man, I noticed it ran better to. I just thought it was all in my head, but now you bring it up it does feel more responsive. So if I set it up right, my speedometer should be right on the money right? My factory code was 919 I think, I can't remember now, but I changed it to I think 872, I would have to look again.
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I've got my numbers written down at work so I'm not sure. I thought mine was stock was around 94X-97X. I have it written down at work. Did you find your tire's revs/mile from the manufacturer for your tire or just base your on tire height? You # looks about right to me.
when all is said and done, I think mine set at 8.85 right now.
when all is said and done, I think mine set at 8.85 right now.
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I got it off tire rack, they didn't have my specific tire on it, so I looked at a couple of different brands of the same size and they were the same so I went with that. I feel like I did it right, but I guess I'll find out when I'm following someone and I call them and see how fast they are going.
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