Anyway to recalibrate Speedo with new overlay?

[Link224]

i bought a custom overlay for my 2002 GT and all the needles line up but the speed, it’s off by 10 mph? Any suggestions?

 

[ttocs]

I guess you could replace the wheels inside the gauge but not sure how you would calculate which one you need.

 

[trebor3170]

You pulled the needles to install the overlays? You haven't changed the rear gears or anything? You don't need to recalibrate the speedo, you just need to get the needle back on in the right place. The best way to do this, I guess, would be to pace someone at a known speed, and reinstall the needle, or you could use up some dyno time.

 

[lutter94]

I used a GPS, and an open road, only lightly install the needle, and check it over and over. Pop it off and adjust as necessary, a copilot could be pretty useful, along with cruise control

 

[Link224]

Thanks for all the help! This is what I thought I’d have to do was pace someone, just wanted to see if there was another alternative.

 

[weendoggy]

You pulled the needles to install the overlays? You haven't changed the rear gears or anything? You don't need to recalibrate the speedo, you just need to get the needle back on in the right place. The best way to do this, I guess, would be to pace someone at a known speed, and reinstall the needle, or you could use up some dyno time.

This is exactly what I had to do. I used my Garmin as well as my SCT to verify speed. Do some 20, 30 and 40mph tests to verify. You may as well check your RPM, volts and water temp too. You can put the needles in loosely then put them where you know the temps/pressure etc. are in a place you're comfortable with. I put my pointers just a tab bit over the mid range for temp, volts and oil. Fuel is going to be the biggest hurdle if you didn't note where it was in the beginning.