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Smaller rims throwing off speedo/odometer

236 Views 6 Replies 7 Participants Last post by  wally05
I posted this a while back but I need to ask again.

Since the diameter of my wheels are smaller, my odometer and speedometer are off. I want to get this fixed. I'd rather do it myself if it's not too difficult. Otherwise, where should I take it and how much should I expect to pay?

Thanks guys!
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I dont know exactly how the speedo is calibrated. (if anyone wants to educate me..... feel free! I would like to know how!)

I think it is something in the ECU that has to be changed. You will not me able to do that yourself and will have to take it somewhere to be calibrated. I have no clue how much that would cost!

there is a little gear thats spins on the output shaft of the transmission and it is connected to a cable or VSS, it is at the back of the tranny, we took apart TH125s at school and its right at the back right where the passenger side axle goes in, to adjust the speedo u need to get a gear with the right #of teeth to go with the size of the tire on your car
What size are your tires?

And there are a few ways it can be calibrated, one is modifing the bin, that is programmed to the PROM in the ECM, another is chaging the calibration of the speedo itself.
lol. You should prolly just stick with right sized tires to compensate for the size of your rims. If you get bigger rims, get smaller walled tires to even it out. I wouldn't want to mess with calibrating everything just for smaller rims, but I'm just lazy! lol

Korey :moon:
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