Need a good rear gear for a LS swap. 308 to 323 worth it?

[Nasty-LSX]

As some of you may know The stepper is getting a LS swap.
1. My tire size is p295/50
2. trans is a GM PERFORMANCE 4L70e 4speed/Auto
3. my rear gear is 308. one wheel wonder.

I want to stay around 2000/2200 at 80MPH. Going to pick up a detroit locker posi and figured
bumping the ratio up would be a fun drive for a auto. I dont want to be in the 2500 RPM range at
75 MPH, Will going to 323 make a difference? Thanks

 

[Snoots]

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With a 4L70e you may appreciate the 3.08 more although a 3.23 is not a bad choice. Soorry I couldn't get the screenshot any larger and IDR where I got it.

 

[CalSgt]

Assuming the 4L70 has a .7 override like other 4 speed autos a 3.89:1 would put you closer to where you want to be RPM wise @ 75 MPH...

I use http://www.grimmjeeper.com/gears.html to calculate this stuff

 

[Nasty-LSX]

here ya go! Gear ratios: 1st: 3.06, 2nd: 1.62, 3rd: 1.00, 4th: 0.70

 

[Turbo4whl]

Here is a uncomplicated gear calculator:

https://purperformance.com/p-29669-rpm-calculator.html

So with the P295/50R15 the 3.23 in overdrive would be 2285RPM at 80MPH. With the 3.42 at 70MPH you would be about 2117RPM. I entered 26.6" as you tire diameter, but tire brands vary.

@ali_c20 Thanks for posting this calculator in February.

 

[CalSgt]

As some of you may know The stepper is getting a LS swap.
1. My tire size is p295/50
2. trans is a GM PERFORMANCE 4L70e 4speed/Auto
3. my rear gear is 308. one wheel wonder.

I want to stay around 2000/2200 at 80MPH. Going to pick up a detroit locker posi and figured
bumping the ratio up would be a fun drive for a auto. I dont want to be in the 2500 RPM range at
75 MPH, Will going to 323 make a difference? Thanks

Just re-read your post... I thought you said you WANT to be in the 2500 rpm range at 75, thats why I recommended lower gears.

@Turbo4whl is right

 

[TotalyHucked]

Just for comparison's sake, I've got a cammed 5.3, 4L65 (same ratios) and a 3.90 gear. I'm running 315/35/20s (~28.7") and I run ~2250 at 70. LS's don't mind RPMs, I'd definitely put a little more gear in it than the 3.08. I'd go 3.42 personally cuz I like a little more oomph in town.

 

[SquareRoot]

Detroit locker huh? I assume you know a Detroit Locker is not a "posi"?
You say you want to cruise at 80 mph so I'm assuming it's a street truck? I SO HATE my Detroit bang bang I'm yanking it out and going back to an open diff until I can afford a trutrac. Your going to hate it, unless of course you never turn a corner.

 

[Bextreme04]

Detroit locker huh? I assume you know a Detroit Locker is not a "posi"?
You say you want to cruise at 80 mph so I'm assuming it's a street truck? I SO HATE my Detroit bang bang I'm yanking it out and going back to an open diff until I can afford a trutrac. Your going to hate it, unless of course you never turn a corner.

I have a yukon Grizzly in 14bff, no noise or banging... but I'm also running an automatic. I would definitely recommend a Yukon Duragrip or similar instead of the Detroit for street driving. Unless of coarse you are running super high power or slicks.

 

[TotalyHucked]

I love my Yukon Duragrip. It's smooth in corners and locks up every time I ask it too. Does good burnouts lol