cliffyk

Why?

2nd gear in the 4R70W automatic is 1.55:1, which with a 3.27:1 axle gear is an overall ratio of 5.07:1 (1.55 * 3.27).

The stock tires have an effective (loaded) diameter of 24.91", making their circumference 24.91 * pi = 78.26" = 6.522 ft. There are 5280 feet in a mile so the tire must turn 5280 / 6.522, or 810 revs per mile.

Putting it all together, at 6250 engine rpm the tires are turning 6250 / 5.07 = 1233 rpm--so every minute the car goes 1233 / 810 miles = 1.52 miles.

1.52 miles/minute = 91.2 mph...

Now it could be that the torque converter never locks up in 2nd, I have no idea as I have never driven or even ridden in a slushbox Mustang.

(In fact I've only owned two cars with automatics in 45+ years, making me far from having practical experience with any of them...)

99BlackPonyGT

i just find it hard to believe that a gt with 3.27s would hit 90 in second gear, when my car with 3.73s is hitting about 6k at 55mph...i dont think that gear calc is correct...



***EDIT....i guess i forgot we were talking about an auto car and not a 5spd...i have no idea what an auto can do since ive never driven an auto stang....my bad