Ironcross

........4.1,or 4.56 and I am using both ratios in my toys.....

Pilot Dan

You're not kidding! That was the main reason for the swap to the 3.08.
I have a wide ratio T-10 (converted) and it gives a nice margin of speed and safety on the highway and is fine around the local roads as well.

thoyer

My 60 came from the facory with 4.56:1 gears. I never drove it with them, pulled the carrier and built up a second one with 3.70:1 gears. I like the way it runs with these gears and the T10.

Tom

Jackfit

L-79 327/350

M-20 wide posi

20,000 miles 90 days

Ave 14-15 mpg

town 12

highway 14-16

3,200 rpm at 69-70

Cruise Control allows foot to rest......makes driving car much easier on long trips....

Rick drives like an old lady

jack

wmf62

with my .73 OD and 3.36 the effective 2.45 is right at the beginning of my torque curve about 2200 at 70, so a 1 to 1 with 2.73 should work fine
Bill

Westlotorn

This has been posted before but might come in handy to help with desired speeds in gears and offers a 5 speed comparison. RPM's estimated with 26.5 inch tires.

bbxlr8

I have been very happy with my L79 close ratio 3:55 in all except extended HW driving (w/side pipes). Been just about perfect for me for all around fun, but as others have said and listed: there are many factors and ultimately it's really all relative to your goals and preferences.

65tripleblack

You're wasting your time and money!

If you have a 4.11 axle now then I'm guessing your engine might not be 230, 245, or even 250 HP. It needs the torque multiplication. If you go to taller gears then you won't be happy with the way the car performs.

Leave the 4.11 alone and switch to a 5 or 6 speed.

Audiophobe

What motor / hp ? 245hp
What type of driving (highway / street)? Both
What average speeds ? Hwy 60-65
Burnouts / Cruising ? No Burnouts
Tranny (Wide / Close)? Don't Know
Tranny (4spd / 5 spd)? Stock 4sp
Is gas mileage a concern ? No

midyearvette

you really need to know if you have a wide or close trans....it has a lot to do with the issue..

fullmonty

I have a 3:08 rear end with the Keisler RS 500, .64 OD. Suits me just fine, a joy to cruise at highway speeds under 2000 rpm.

fullmonty

I have a 3:08 rear end with the Keisler RS 500, .64 OD. Suits me just fine, a joy to cruise at highway speeds under 2000 rpm.

wmf62

3.08 is as low as i would go
Bill

wmf62

what engine?
Bill

rustylugnuts

Copied this from a previous reply;

Just did some quick math; RPM of gear ratio depends on a given speed, and tire diameter.

RPM = 70 mph, x gear ratio 4.11 x 336 divided by tire diameter. (6-70-15) is 27.42 = 3,525 rpm's.

As for the 3.70 ratio using the same math = 3,174 rpm's

And the 3.55 ratio = 3,045 rpm's

Changing this ratio from a 4.11 to a 3.70 saved a whopping 351 rpm's at the same speed. I suggest going to a 3.55 from a 4.11 makes a noticeable difference of 480 rpm's.

By far the best overall ratio is: 3.55 regardless of transmission with final ratio of 1 to 1 period. It will accelerate nicely from a dead stop and has a decent cruise speed to rpm ratio.

rustylugnuts

bbxlr8

I definitely second this per above and have messed with sooo many ratio's in multiple cars. Knowing C or W ratio trans is a factor.

Now, ask me how I feel about my worked 455 Olds (torque motor) with 3:73 & auto trans. Great for short bursts but am going crazy otherwise and not driving as much. I am shopping a Keisler if I switch or maybe one of the OD auto's (in all my free time - ha)

midyear

I put an overdrive in my old 67, changed gears several times, settled on a 3.55 because of my cam choice, did well on the highway and got great gas mileage for a BB (18-21.6) put almost 100k pleasurable miles on it. my best friend has a 66 390/427 m20, we put 3.08's in it and have driven it everywhere over the past 10 years. my current 66 just went from a 700r4 w/2.59 gears to a 6 speed w/3.08 gear, 6th is useless, I plan on 3.73 gears later to give me about the same cruising RPM s as I previously had. highway gears in a street car are really only noticeable in 1st gear...after that they all feel about the same...

FastEddy

best all round rear for everyday small block for everyday use is a 3:55. It's the middle ground.

As you go towards the 4:11 direction, you get better acceleration, but have a noticeable shorter time in first gear(gotta grab second sooner), and cruise gets worse...

As you go towards the 3:08 direction you loose acceleration, but have a longer time in first gear, and cruise gets better.

5 spds ALL have a lower first gear than the 4 spds, so it all changes for those.

Best thing to do is drive someones car with the gear ratio you think you want, with about same power level and trans....

Audiophobe

That's the way I'm going to go. I'm not taking long drives on the highway, usually anywhere from 5-25 minutes going to a cruise or a show. The furthest I've driven so far is 65-75 minutes each way, once.
So I think I think the 3:55 as you said will give me the "middle" I'm looking for. It certainly will be at least a little better.
When it's in I'll follow up if anyone's interested.

Sky65

Yeah I think it would pull fine. I'm turning about 2500 at 70 right now which isn't bad and I like the 1st gear overall ratio. 1st gear is like having a 4.56 and it will light up the 275/50 17 tires on a roll. I like that.