RXDawg

Got a 69 roadrunner while in the process of putting on rear disc brakes toying with idea of changing rear end ration from 3.23 to something else. I don't want 4.10, but I think I want a bit more aggressiveness. Right now the car has a 3spd 727 automatic which I will be removing and changing back to the original 4spd manual later this year. All of this to get to my question of what would some of you recommend as far as the ratio? 3.55, 3.91, or simply leave it as is? Or when I change back to the 4 speed will the 3.23 work pretty well? I'm not too concerned with highway speeds and rpms because I will only drive the car once or twice a month and probably for no longer than 30 to 45 minutes. just let me know some of ya'll experiences. thanks guys

67 GTX

i have a 440, 4-speed with 3.54
they seem fine

Commando

What is the size of the differential?

thedusterridesagain

i had a 318 4spd set up in my old duster and it had the suregrip 3.23 gears in it. i loved it. great freeway gear and pretty damn mean on the launch. ill be honest i took a z06 vette off the line ........ till he hit second gear. but the point is i was in front of him first. if i was you id stick with them. im lookin for a set myself right now actually. any one want some 3.55s?

challenger

if it was mine id go 3.91 and beat that Z06

78D200

What do you have for a motor and what size tires are you running?

3.23 is a good ratio to have if you want some fun and still cruise. If you just want fun, then I would go to a 3.55 to 3.91 ratio, depending on what you have for a rear axle, motor and tire size. Look into yukon for gear sets, they pretty much make every single size ratio for just about every rear end.

RXDawg

I've got a 440 bored 60 over. 10.25 compression. Like I say I do want to go back to the 4 spd manual later in the year. I'm putting on 18" wheels I do believe in the rear maybe 17's up front. I'm not sure about the tire height yet. Have to measure b/c I'm dropping the car 2" in the rear

challenger

smart thing about the cheby thingy

thedusterridesagain

3.91 would have been nice but at the time it was my only car and i lived 20 miles from base. little old e-4 me at the time didnt have that for gas. pluss im by no means a slow driver.

blue 68 gts

Just go with 3:55's.

they are good for freeway driving, street driving, and great for the track.


In my Dads old swinger, he had a mild 440 w/ 727, 8 3/4 w/ 3:55's. It would run 11:80's back in the early 90's. And he drove it 60 miles one way to the track.

I'll have the same set up with 3:55's. But once i get a towrig, I'll be uping to 3:91's, or 4:10's.

RXDawg

I think I'll go with the 3.55........next I've got to figure out some cool tires and wheels.....had some 15 inch cragar s/s with low profile mickey thompson....I love the look, but I want some bigger wheels. What do ya'll have on that?

67 GTX

I have 15'' cragar S/S
i have a little bigger tire in the back than front
i just got BF Goodrich Radials