Do gear swaps throw off the odometer?

[N/A Cobra]

I just switched from a 3.27 to 4.30 and have not done the speedo fix yet. Does this throw off my odometer as well as the speedometer? If so, I need to get the speed cal asap. Thanks.

 

[99SVTAddict]

Yes it does...the gear is spinning faster, making it look like you are adding more miles than you really are. Not sure of the ratio, but enough where I would want to correct it ASAP.

 

[missouri_guy197]

It's gonna add a whole lot of miles...I'd get a speed cal as soon as possible...I didn't know I had 4.10's in my car for about 3 months after I bought it used and drove around a lot with it like that and I probably added 2000 miles extra to the odometer than it actually has...

http://www.brothersperformance.com/shop/mustang/brospeedcal.html

 

[N/A Cobra]

Thanks for the help guys, I just ordered a Speed Cal from Brothers Performance, so hopefully it will be here before the weekend.

 

[N/A Cobra]

Is there anywhere I can find the instructions for the Speed Cal tool? How to install it on my car.

 

[missouri_guy197]

It will come with very detailed instructions with pictures, but here's dallas mustangs webpage on how to install it:

http://www.dallasmustang.com/index.mvc?Session_ID=fd1f5aa12601961f7a5c8c785914d220&s=SpeedCal_Inst

Also, here's their calculator to set it for different sized tires even:

http://www.dallasmustang.com/index.mvc?Session_ID=fd1f5aa12601961f7a5c8c785914d220&s=speedcal