Gears

Im wondering what gear ratio i need. I have a pretty much stock 5.3 with a 4l60e transmission and a np208 transfer case with 35's. I was thinking 3.42s but im not sure. Any opinions would be greatly appreciated. Thanks!

i would go 3.73 imo better allround gear with that tire

I would say at least a 3.73 may wanna go bigger if you're mudding like a 4.10, 4.56 is also popular

4.10's with 35's.

You'll need 6 turbos if you want 42's and 35's.

4.56

I got 4.8, 4.56, and its perfect with my 35's.

Go to nationaldrivetrain.com, they have a chart. AND awesome prices.

I have 4.56s, with 35s.

Thanks guys im just looking to run around 2300 rpms at 75 so maybe i will try 410s and see how they act

I'm also running the 4.56 on 35's.

I would go at least 4.10's and maybe even 4.56's. With the larger tire and 4.10's that would act similar to 3.42's (actually around the 3.51 area) with a stock tire height of 30". Where the 4.56's would act more like 3.91's with a 30" tire.

3.14 (Pi) x 30" = 94.2
3.14 (Pi) x 35" = 109.9

109.9/94.2 = 1.16666

4.10/1.1666 = 3.51
4.56/1.1666 = 3.91

Someone feel free to correct me if my calculations are off.

why would you gamble and try something as expensive as a gear change and then change it later. Its not like changing an air filter. Do it right once. if you are gonna have 35s and are not going bigger, 4.56. if you plan to go bigger 4.88

If you like your highway mileage stick with 4.10s.... I miss mine.

But the 4.56s sure make it fun to light up the 35's :)

I have 4.88's on 35's and at 70 mph push 2500 rpm, but I plan on 37's! I'd say 4.56's, but 4.10's will get the job done.

Edit:
I used one of those rear gearing calcs online, to be exact I'm at 2296.48 rpms at 70 mph with the 35's. Kinda hard to tell when your looking at the gauge and it might be off a touch, who knows....

4.56 or don't even bother with it

haha well i definately need something different from my 3.08s i am just afraid of killing my mileage thats all and its pretty split half and half. I think i will go with 4.10s but just out of curiosity what do you guys run for rpm's at highway speeds? Thanks for all the help

I turn 2296.48 running 70 mph, that's with 35's, 4.88's, and the 4L60E tranny. There is a decent calculator at: Transmission / Rear Axle Gearing the only thing is, it only goes up to 4.56 gears, but I think 4.88's would be overkill unless you plan on going bigger.

With the 4L60E, 35's, and 4.10's running 70 mph you'd be at 1930 rpms. With the 4.56's running 70 mph you'd be at 2147 rpms. Not a huge difference, but throw a trailer behind it and you'd want the 4.56's, for the torque!

just do the 4.56, be much better and your tranny will love you more

Thanks for all the help guys and that website was also helpful. 4.56s it is.

Your pinion gear is gonna be tiny, and weak. I hope you're not gonna pound on it too much.

The pinion gear on the 4.56's is a great deal smaller than the pinion gear for he's factory 3.08's, but the 10 bolt by itself is very weak unit. For daily driving and occasional offroad use he'll be fine with the 4.56's. Alot of the lifted guys run 4.88's and 38's and do just fine daily driving and some offroad. Now, get up to the 5.13's in a 10 bolt and you'll snap a pinion under heavy torque quick as hell. You could always upgrade to the 14 SF later down the road....

I have a set of 3/4 ton axles laying around i just don't want to buy new wheels.

There is a lot of Guys around here running 35's with 4.56's in there 10 bolt, inculding myself... Even with a good amount of abuse, they are still holding up just fine...

You can plug in your setup and do side-by-side comparisons using my gear ratio calculator to see how swapping gears and tires will change things:

http://www.grimmjeper.com/gears.html