questions about rear tone ring 7.5 vs 8.8 tooth count

[pjtoledo]

comparing 2 differential carriers I found a different number of teeth on the tone rings.
1999 7.5 4.10 open has 102 teeth, it's from a reg cab 4wd. (coming out)
2004? 8.8 4.10 open has 108 teeth, it's from an extended cab 4wd. (going in)

that's about a 6% difference
any idea why the 2 different sizes??

I'm guessing that may be because of the different size factory tires, 6 % more ticks to compensate for a 6% larger 2004 tire?????
or did Ford put different parameters in the GEM unit just to screw with us?


the approx difference between 235-75-15 and 245-75-16 is about 6%

 

[Uncle Gump]

size difference in the carrier... bigger carrier... more teeth.

 

[sgtsandman]

Bigger diameter, so needs to have more teeth to keep the spacing the same. As long as the basic axle setup for the sensors is the same, there should be no difference to the truck in operation.