rear gears question

[88stanggonebad]

im getting ready to order rear gears for my 1967 mustang w/ 289 and a c4 tranny and a 8" rear. i was thinking 4.11 but i would like to know how high my rpm's would be at say 65mph. i wont be doing to much freeway driving but but it might. would i be better off with 3.80 or 3.55?

 

[iskwezm]

I think a 3.80 is better, it will turn about 3200 st freeway speeds if i can remember(went to a 5 speed)

 

[HookandLadder]

Depends on the tire you are running, but 3.50's are much easier on the motor for highway miles.

 

[65notch]

i went with 3.55s with my c4. i have a mild 289 and i was turning about 3200-3300 or so at around 65. it was pushing it a lil, i would stick with 3.55s, dont go any higher unless you plan to get an overdrive or 5spd.

i wish i would have gone with 380s because i just swaped to a 5spd, but gears arent to much money so i may change them out again later on.

 

[mfp4073]

my 3.89s are about 4000rpms at 80, i think 3.55s would be a little more enjoyable for me.

 

[rbohm]

unless this is a race car, stick with 3.55's. that is the lowest all around gear you need for a car as light as your stang. anymore is a waste.

 

[FORCED2DV8]

3.55's are the most you want to go on the street, You will be around 3200 rpms depending on tire size. Even if you have a 5 speed they will drop to 2300 or so.

 

[68RCodeConv]

I have 4.11 in my 67 GT350. Believe me, you don't want them on the freeway.

For a mostly stock 289, 3.55 is plenty. If the motor has been built to rev to 6000 or more then you might consider 3.75 or 3.89.

 

[66moneypit]

http://www.stanginfo.com/Gears/GearOptions_view.php

 

[57fairlane]

I couldn't decide so I went with a 3.80. I run 275/60/15s (28") on the skreet which gives me an effective gear of 3.56s. Then at the track I switch tire sets to a 275/50/15 ET Street radial to use the extra gear.