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Discussion Starter · #1 ·
Does anyone know of a place that does speedometer recalibrations in Austin? I got pulled over the other weekend(first time for speeding in the BKO:rockon), my speedometer showed 50, but the cop clocked me at 69. Of course, that was before I got my 4.56 gears installed, but I am still around 10 mph off. Anyone have any suggestions? :popc1:
 

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Discussion Starter · #4 ·
:stupid
Save yourself the money, George. That's the post I used to redo mine. Took longer to do the math than to complete the actual procedure. Very easy to do.

I just found out the RevPerMile - 613 for the ProComp tires, but what else do I need to know if I have 4.56 gears? I just use the 613 and go with that? I used 598(BFG Mud Terrains) but I was wrong it through my speedometer up 10-15 MPH.
 

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IIRC its all about the tires with the speedo... i could be wrong but once i P'ed my PSOM mine read true again (which is nice with all the cops around college station)
 

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As stated by the others, only the tire size affects the speedometer. The tone wheel (looks like a gear with lots of tiny teeth on it) for the speed sensor is bolted between the ring gear and carrier. Therefore, it spins at the same speed as the carrier and is not affected by changes in gear ratio.
 

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Discussion Starter · #8 ·
Well, I did it, and it worked. I messed up the first time and just put in the RevPerMile, not the Constant. My number was 8.28 or 828, is that what you got Dale? Since you and I have the same tires.
 

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Well, I did it, and it worked. I messed up the first time and just put in the RevPerMile, not the Constant. My number was 8.28 or 828, is that what you got Dale? Since you and I have the same tires.
I can't remember, but it took me two tries as well. I think I messed up the math or something, because after the first try, it was off by the same amount in the other direction. (speedo read way too fast instead of way too slow) For the second try I split the difference between the original setting and my calculated one. Hit it pretty close to dead on, now it reads 72 mph when my GPS says I'm going 70. Its dead on at 45 to 50 mph. I can live with that since I rarely drive it faster than 40 or 50 anyway. Except of course when I bring it to Austin for M&G's at Hooters.:thumbup
 
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