Gear ratio and rpms

[Gumby84]

i am wanting to put a set of gears in my stang 5.0 auto. i was wondering with my auto what the rpms would but if i put a 4.10 or 3.73 in it at around 80mph. also who has the best gears and do they cause whine or are they louder then stock?

 

[toyman]

i am wanting to put a set of gears in my stang 5.0 auto. i was wondering with my auto what the rpms would but if i put a 4.10 or 3.73 in it at around 80mph. also who has the best gears and do they cause whine or are they louder then stock?

Any properly installed gear sets will NOT whine. Gear ratio is irrelevent. RPM in O/D at 80 mph are: 4:10 - 2850 & 3:73 - 2650 assuming stock tire size.

 

[Dino Dino Bambino]

I have 245/45R17 tires, a 3.73 gearset, a 0.70:1 overdrive 4R70W, and at a correct 75mph my tach reads 2700rpm.
With a 0.67:1 overdrive AODE it'll be 2600rpm at 75mph using a 3.73 gearset, and 2850rpm at 75mph using a 4.10.

 

[slayr281]

I'm not sure what year Mustang you have, but I'm doing these calculations on the assumption that you have 245/45/17 tires, currently 3.27, and your AOD overdrive is .67 (4r70w is .70)

--rpm-----3.27------3.73----4.10---
1500----52.31-----45.86---41.72
2000----69.74-----61.14---55.63
2500----87.18-----76.43---69.53
3000----104.62---91.71---83.44