I have a 4dr jk with 3.73 gears and an auto tran. Having a problem with deciding on what gears to install. I have 33" truxs which still have a good amount of tread on them. I do mostly highway driving but I do plan on going to RC alot more this year. What does everyone thing about regearing with the 4.56s f/r, front locker and chromoly shafts. At this time I do not plan on running 35s. Also it would hard to find someone wanting to buy 33s so I could go up to 35's and do 4.88s

Is anyone running 4.56s with an auto and 33s. If so I would like to hear from you or anyone else for their opinion.

 

Don't do it! I'm running KM2 33's with an auto and let myself be talked into 5.13's instead of the 4.56's. The Jeep is ready for the 35's when I get them and now driving is effortless. That JK would work itself even on small hills and now it doesn't even think about going up stuff. Go with 5.13's instead, you'll be happy you did.

 

I agree if you're going to go with 35s soon you'll want 5.13 with the auto.

 

Interesting. Could you stand the 33s and 5.13 permanently? What's your RPM at 60?

 

Your gas milage would drop signifcantly. Go with the 4:56... You Jeep will ride great. If you go to 35", you will notice a slight drop in performance, but it is doable.

If you know you are going to eventually go up to 37", go with the 4:88s. I think the 5:13 or too weak for a D30 (ok... here comes the beatings).

 

I wouldn't gear for those 33s. You will likely regret it. All I could think about after getting 33s was getting 35s. If you think you are going to go 35 or 37 then get the 5.13. If you don't you will be sorry. I would just save up though while I had my 33s for sale and gear and tire all at once. That is what I did, except I traded my tires to the dealer for $400. You probably cannot sell 33s here, but try a TJ thread where everyone is rolling 4" lifts and 33s. Good luck!

 

I'm very pleased with my 33's and 4.56's but I have a manual transmission. I think the 4.88's on an automatic would be similar, but I wouldn't go any lower unless you're sure you won't be on 33's for long.

 

Great question Red. I think I would go 5.13's if I were still running stock Rubi's. Before I post the numbers let me tell you what's rolling here:

First of all put away your calculators and some table you found posted somewhere on the I-net. I'm gonna tell you what is, not what's supposed to be. If you want to call me a liar then come out here and do it to my face. Then we can go on to important stuff like rolling over your calculator a couple of times and getting on to wheeling some great trails.

Now this used to be an '07 Sahara Unlimited with an AT. Stuff that may effect the numbers include full RH skids, full doors, hardtop, Shrockworks sliders, Nates 4x4 full width bumper, 9500ti winch, Currie (massive) control arms F&R, diff armor, chromoly axles F&R, wheel spacers, Tuffy everything, RH rear bumper/tire carrier, j-can carriers, at anytime about 50 lbs (minimum) recovery gear and me -working hard on seeing the underside of 200 lbs (no wife jokes please ) for the first time in many years.

It's running a D44 in the front, an Atlas 4sp T/C with about 750 miles on it and the 5.13's have about 250 mi on them. Almost its entire life has been spent at 6,000 feet or better.

I reset the gear ratio and tire size (measured at 32" BFG KM2's siped and running at about 32 PSI on stock Moab {Rubi} wheels) with my new AEV pro whatever just yesterday. If you're regearing, buy one of these now! 'Nough said .

Here's the numbers taken from the flatest part of the highway. By the way Red, I sure am glad that Statie had somethin' else to do as I was so busy lookin' down at the gauges and not the speed limit signs.
45 mph 1500 rpm
50 1800
55 a hair under the 2000 mark
60 2100
65 2300
That was as fast as I dare go. Oh yeah the MPG thing never dropped below 18.7 for whatever that's worth.
Now for the best part, I PASSED TWO TRUCKS GOING UPHILL! It's been a long time since I've been able to do that.
It's also the first time in who knows when that I didn't have to turn the overdrive off on that road. I would do this again in a heartbeat.

 

Trust me I have been pondering this desicion for several months.

What is your rpms at 60 mph. I would think that your jk would be screaming at 60. I know i am not going to 37's. But 35's are not out of the question in the future. By the gear charts it shows the 4.56s on 33s running at 65 mph my rpms would be approx 3300 (overdrive off and I add the 200 for slippage). So with just a good quess i figure my rpms would be approx 2100 with overdrive on. I could deal with this for a while and it would bring the jk back to life.

I think I will try and sell the 33's first on a TJ forum before making my final desicion. Thanks for that advise. All your comments are helpful.

 

What's wrong with 2100-2300 rpm at 65 with overdrive on? That's roughly what my 5.13's are giving me.