so why does and extra 5 rotations mess up an auto tranny's braking abilities so badly? crawl ratio with 3 spd auto, atlas, and 4.10s:

38:1 with 3.77
43.5:1 with 4.33

so why does AA recommend that autos use the 4.33? my 3 speed does engine braking on its own, i don't have to apply the brakes as much as in a modern car.

i'm goin with 3.77 anyway, just cuz i want to be able to hit 20mph in some spots! hahaha

wow no responses in 12 hours. so why is a 4.33 better for a manual and a 3.77 better for an auto? c'mon... i'm curious here

Because your engine's idle speed is enough to push the 4.3 gears and overpower your brakes.

the extra torque multiplication... remember, with an auto you will have a torque convertor, so you can "fudge" the number on your crawl ration by basically double. That extra torque is just that much more coming out of the torque convertor that your brakes will have to stop... some rigs literally can't stop.

so basically it's the same reason that a 3 spd non lockup auto will have 3.31s while a 4 spd manny will have 3.54s? gotta love slushboxes...