I am doing a axle upgrade on my 97 tj Im running a dana 44 in the back and a 30 in the front with 33 bfg's what gear ratio would work best with the three speed auto? 4.11 or 4.56 any help would be great!!!!!
I run 4.56 with my 35's and my Jeep has a ton of heavy stuff bolted to it. Off-road no problems. On road, I do have to down shift on some hills, but its not bad. Thus with your 33's you could go either way, If I had to pick though, I would go with 4.56's for two reasons: 1st, if you ever decide to run bigger tires you will be okay and 2nd, if you do add a lot to your jeep then it will help to counter that for your on road driving. And to add even more I drove a buddy's with 33's and 4.11's and it was fine on the highway, even did great with cruise control on hills.
With an auto tranny I would say go with the lower gearing... if you are towing anything, it's a no-brainer. I believe your auto transmission has a 1st gear ratio of 2.74 to 1 compared to a manual tranny 3.83 to 1. So, the 4.56's in the axles will help compensate allowing for easier starts, particularly when towing. You'll also prefer them on and off road climbing hills. If you have a 4 sp automatic it would have an overdrive which will keep you spinning at acceptably low rpms at highway speeds. And of fairly significant consideration, steep descents off road are usually handled better by manual transmissions b/c 1st gear allows you to crawl down slowly without using the brakes... thus keeping you in control of your Jeep. Deep axle gears will give your auto tranny that advantage and keep you from stalling out while crawling down slowly.
With an auto transmission that sees significant highway miles, you will like the 4.10's better. The higher first gear in the auto is compensated for by your torque converter which will multiplies the engine torque up to 3 times... This will give you the acceleration that you need around town and on the Highway. I know a couple people running 4.10 gears with 35" tires and some that are running 3.73 gears with 33" tires, so with 4.10's you will be fine with your 33s.
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