7.5 to 8.8 speedo error

[Kim]

I think I have found the reason why my speedo is off. My Ranger had an 8.8 swapped in place of the original 7.5, and the speedo reads fast.

Larger diameter tone gear with more teeth being picked up by the sensor?
What can I do to fix this...I'm assuming a 7.5 tone gear will not fit in place of the 8.8 version. I don't think I want to grind a few teeth off the thing either lol

Ideas? I'm going to be in there swapping the gears eventually anyway, so I should find out what I can do to fix the speedo error as well.

 

[RonD]

They don't make tone rings with different tooth counts.

1998 to 2000 speed sensor goes to ABS module, ABS module is what has the speed calibration correction software.
It is given the "rotations per mile" number at the factory and then sends the speed pulses out to speedo, cruise and computer.

You could get an 8.8" ABS module.
Axle ratio doesn't matter with this setup since it is measuring rear axle rotation not drive line rotation.
Tire size of course matters, so if you are not running stock tire size then having current ABS reset for 8.8" and tire size would be better.

 

[Kim]

I'll look into that then. Thank you!