70351cmustang

Looking to replace my stock 2.73 gears in my 91 GT w an AOD trans. Wondering what kind of rpms others are turning at 70 mph with 3.55s and 3.73s. Not my everyday ride but do run down the interstate every now and then....Thanks

r.barn

i remember people saying it's not that bad. with 4.1's they were
like 2,500 at 70-75, you should be fine

94Cobrakid16

i think with 4.1s youd be a lil higher than 2500, cause i got 3.08 with a 5 spd and at 80 its at 2100 rpm.

Tims 88GT

my car at 70mph with 3.73 gears and a 25inch tall rear tire is 2100rpm in 5th

ikeybmg

mines 2250 with a slighly shorter tire.

Tims 88GT

your tire is shorter than mine? thats crazy

ikeybmg

yea lol, 275 35 18 is short. actually close to the same id say, i need to calibrate my speedo since i got the new speedo gear, its still just a lil off i think.

Tims 88GT

when they are worn out they will be really short. do they hook good?

meiguoren33

Simple math, 3.73/2.73=1.366. Mutliply your RPM's with the 2.73 at 70MPH by 1.366 and that will be your RPM's with the 3.73 gear at that speed.

ikeybmg

you wouldnt believe it. i didnt think they would, the 17's with 275/40 would spin a long as you wanted in sec and leave a nice mark in third. these hook second alot better, they wont spin all the way out in second and only a good chirp in third. this is with me trying to spin ...lol. but i think they will be kille with 285 drag rads. i cant get a holeshot with either wheel size in first though. its nothing but spin in first. but the u/l ca's and subframes will help along with the draggers i think.