gear question

[afjeep]

right now im running 3.07s(and hating them) on a 3 sp auto. what kind of results am i looking at if i run 4.10s. i know i dont want to go any higher than this with 3 speed auto but right now i get 11 mpg with 32x11.50 km2s. thanks for any help.

[Ricky Booby]

I was running 4.10s with 31s in my old XJ (auto). You will be fine. No issues. Gas mileage will get better. I am running 4.88s with 33s in my current TJ.

What vehicle are you running? Just get a set of axles out of a 4cyl XJ or TJ, they come with 4.10s from the factory. The front will bolt right up. You will need to get a new axle bracket kit for the rear if you get it out of a TJ.

[afjeep]

I was running 4.10s with 31s in my old XJ (auto). You will be fine. No issues. Gas mileage will get better. I am running 4.88s with 33s in my current TJ.

What vehicle are you running? Just get a set of axles out of a 4cyl XJ or TJ, they come with 4.10s from the factory. The front will bolt right up. You will need to get a new axle bracket kit for the rear if you get it out of a TJ.

got a tj. im picking up a rear d44 housing tomorrow so im trying to kinda get an idea of how i wanna build it. the front will have to wait for now. thanks for the input. anymore is welcome.

[Ricky Booby]

What gears do you plan on using (Yukon, Genuine Gear, etc.)? Are you doing the setup yourself? Plan on running a locker?

[afjeep]

What gears do you plan on using (Yukon, Genuine Gear, etc.)? Are you doing the setup yourself? Plan on running a locker?

got no clue about the gears yet. that was planned for a whole nother post. haha. planning on a locker. probably arb. open to suggestions though as always.i still have a lot of research to do. haha. i've never done gears before so im not sure i'll do it myself. not that i couldnt, it just might take a while. haha. depends on install prices around here.

[SGM O]

My recolection is that the 3-speed auto always had taller gears than the 5-speed manula in the earlier TJ's. I have the 5-speed which came with 3.73's and I ran 31" tires with no issues. I went to 4.56s when I did my ARBs and with 33's the TJ did great in the Colorado Mountains and I had no issues doing 75 mph on I-25/I-70. My mileage averaged around 14.5 mpg. When I went to 35" tires I found that my mileage improved to about 16 mpg as long as I kept it under 60 mph, but I had to use 4th gear to pull a hill or if there was a head wind to maintain 75 mph on the hwy. Here at Fort Lewis I am still getting around 16 mpg but I can easier pull the hills in 5th gear now that I am back at sea level.
My guess is the with the 3-speed auto, in and around GA you should be okay with 4.10/4.11 gears and up to 35" tires but don't forget to change out your speedo gears so it and your odometer work correctly, or you will never get an accurate mpg calculation. Also the tire and wheel combination will effect mileage. My 35"x12.50" BFG ATs on alloy rims give me a good mile to the gallon better on the street than my 35"x12.50 Trxus MT do mounted on steel rims.

[CutterN55]

I have a Torqueflite 727 3 spd Auto in my GW. I lifted and went to 33x12.50's with stock 3.31 Dana 44. Wasn't bad, when I wanted torque, four low would get me through anything. Eventually, I did beef up to 4.10 thick gears and was able to re-use the carriers & saved some $$$. 4.10 with 33's is closer to stock ratio, if you want more torque 4.56 will do you fine with 33's and would take you ap to 36's.