razz924

i have a 08 sahara unlimited auto with a 6" teraflex and 35" pro comps with superchips programmer, aem brute force intake system. has stock 3.73 now but cant decide to go with 4.88 or 5.13 or even 5.38. my wife drives it daily up and down the highway and some interstate. what rpm's do you guys run at 60 or 75 with lower gears?

ironworkerlu21

I decided on 5.13's for mine.....At 75 mph i'm running roughly 3200 rpm in 6th gear, with 35's on stock rubi wheels. Very happy with the choice. Hope that helps.

Curiosity

if you're going to wheel it 5.13's seem to be pretty good for 35's, but is the stock 27 spline d30 strong enough to really handle anything more than 4.88s?

nthinuf

Start with the Drivetrain FAQ stickied to the top of this section. There is nice little chart that just may answer some questions...

(just be sure to use the 'actual' tire height, not the mfg's listed height)

RedneckJeep

With 35s and the auto, 5.13s seem to be the way.

spinlock

I am running 5.13s and 35s and with a 6" lift I would go at least 5.13's, probably even the 5.38s because that much lift will create more drag (an oxymoron in aerodynamics). You'll likely be happy with either ratio at lower speeds.

At 70-75 MPH these ratios put you right in the power band, the problem is when you drop out of overdrive the RPMs shoot up to ~4000. That's not close to the redline but not where I want to cruise for very long.

nangulator

I have an auto trans with 35s & I am going with 5.13s

aldaman

I have an auto as well running 5.13s with 33s...Will upgrade to a 3" lift and 35s in the near future...As of now I really like the added pep the 5.13s provides...I mostly do city driving though...

BlackNorthernJK

well, unless you've got a d44 up front you can't run anything higher than 5.13 anyways...unless someone has finally made 5.38's for our jk d30, and no...not old d30 gears, gotta be jk specific

JayhawkJeep

Some day when i have the money$$ I plan on going from the 3.73 to the 5.13. There is not coubt.