4.10's, tires, and aod

[bart]

ok guys ive searched but i cant find the answer. ok i have an aod, and i finally got convinced that i needed to get some 4.10's. so i got some out of an f-150 the other day. anyhow, ive read a few things that have me worried a little. my tires are only like 24.5" tall. i keep seeing this 26" number pop up.

are my tires not tall enough? they are 245-40/17, i figured it was just a tad shorter than what most of you guys are running, 245-45/17.

i have 3.73's right now, i pull about 2400@65-70 mph, am i gonna hate swapping them? this is my DD, i have to drive 80 mile round trip 3 days a week. i do like 65-70 on the highway, im not in a hurry. lol. but i do want that bottom end kick back.

for mods and whatnot they are on the www

thanx for any help.

 

[N8Miller]

i have 3.73's right now, i pull about 2400@65-70 mph


wow, i do that in 4.10s and a 5 speed. are you sure that you only have 3.73s in an auto and do that RPM? sounds like you a different gear in there. i do 65-70 at 2350 rpms exactly.

 

[bart]

well, unless my speedo is wrong. i know the tach is on, it takes right around a a grand more to get up to the cam, its an e-cam and ya know they come on at 2500.

hell ive probably been doin like 75-80 then, cuz when i did the swap i had to get a new speedo gear, probably got the wrong one

 

[davs5.0]

What year is your car? Most pre 94 aod's came with an 8 tooth gear in the trans and switching the driven gear to a 23 or so will not correct the speedo. You're probably still off by 5 or so mph.