I don't understand why people are so scared of low gearing. It doesn't make it rev high all day, everywhere you go when you do it right. lol

4.56 with 33's put me at about 2400 rpm at 70 mph. with 4.56's and 35's at 70mph I am about 2300 IIRC.

 

I have to say i am running 33s and was goin to look to run 4.10s and a 8.8 ls rear but after following this i thonk i am goin to push for 4.56s. I am new to this forum but have read and learned alot. Thanks alot guys.

 

go 4.88!!!

 

if your jeep was stock with 3.55's then im pretty sure you have an auto tranny. auto tranny's are different than manuels as far as top gear, my top gear isnt as high as the autos, its lower, so therefore my manuel with 4.10's is close to your auto with 4.56's.

 

and here where i live, the next closest towns are at least 40 minutes away, on I-80, so for at least 40 minutes about 70 mph is the minimum i have to run to not get tailgated by them dang utah drivers.....sorry if your from utah but im only being honest lol so i need something that im not taching 3 grand going 75, with the 4.10's and 33's ill be 2480 or so at 75...but i may also run 32 inch tires, so i may tach even more. i know i wont be going bigger than 33's, i have another beater jeep i can build into a gnarly crawler and put on 35's and 5.?? gears in lol

 

Hey! lol Utah drivers blow, signals and proper space are not something they know about!

But sounds good. I loved my 33's 4.56's.

 

i have 4.56 on 33s and its perfect for DD. also id say it gets better millage then my sisters stock wj.

 

Remember that you want to keep the engine in it's peak power band when you're at cruising speed and from my experience, 2480 is not enough RPM/power too push these bricks with heavy wheel/tire combos through the wind. I'm shooting for closer to 2600 at 75mph.

 

im over a week in to having 4.88's on 33 inch tires coming from 3.55's and 33's... My jeep ROCKS now.. 2400 rpm at 65 is more than comfortable...

4.0's are a short stroke motor, they like to turn some RPM's for heavy load use. And yes, even with the smallest of lifts, as said above, it takes a lot to move our flying bricks through the wind... wind tunnels were nothing but tornados to the engineers of the Cherokee ......

at 65mph, i can comfortable accelerate on flat ground without downshifting, but if I want to pass someone, or am doing the mountain thing back home in VA, i still downshift... 4.88's and 33's provide a ratio that should have been factory!!!

i was worried when i decided to order the 4.88's too, but now that I have them installed... i wouldn't change my mind for anything!!


and for what its worth... 90mph is even comfortably obtainable with such a ratio , in case you have a heavy foot

 

Hmmm i was thinking of going with 4.56 for my jeep but maybe I'll do 4.88 now lol

 

I don't think you would ever regret going 4.56's. 4.10's might get you back close to stock final drive ratio but with the extra oomph with the 4.56's will help make up for the additional weight that adding much larger tires and heavier equipment that generally comes with a lifted vehicle.

Lower gearing will probably increase you MPG in traffic and city/mixed driving, due to the engine working less from stoplight to stoplight. At highway speeds it may suffer a little bit but again I bet it will be negligible.

 

k so this is what i have, with my aw ax-15 5 speed transmission, these are my rpm's in high gear

33's and 4.10's- 65 mph- 2144 rpm's 75 mph- 2473 rpm's
32's and 4.10's- 65 mph- 2211 rpm's 75 mph- 2551 rpm's
31's and 4.10's- 65 mph- 2282 rpm's 75 mph- 2633 rpm's

33's and 4.56's- 65 mph- 2384 rpm's 75 mph- 2751 rpm's
32's and 4.56's- 65 mph- 2459 rpm's 75 mph- 2837 rpm's
31's and 4.56's- 65 mph- 2538 rpm's 75 mph- 2928 rpm's

33's and 4.88's- 65 mph- 2551 rpm's 75 mph- 2944 rpm's
32's and 4.88's- 65 mph- 2631 rpm's 75 mph- 3036 rpm's
31's and 4.88's- 65 mph- 2716 rpm's 75 mph- 3134 rpm's

this is where i would set, and with all the interstate driving, and the fact that i am leaning more towards 32's than 33's, i know i dont want 4.88'sm but im having a hard time deciding between 4.10's and 4.56's, cuz 2800rpm+ would just be too much on the interstate, but usually i run between 65-70ish and just deal with being tailgated lol, so im not totally sure...

 

I also forgot to add that my gas mileage improved DRASTICALLY


3.55's and 33's = 11mpg on totally flat interstate driving at 65mph or LESS
4.88's and 33's = 17mpg+ on mountainous (some very, very steep and with multiple mile climbs) interstates, traveling in excess of 70mph, mostly at around 80mph....


obviously, HUGE improvement!!!

 

@Sheepdog, Given that you have a manual, and dont plan to go to 35's(it sounds like 33's could possibly be in your future) I would go with the 4.56 gears!! you would obviously, by your chart, be running around the same ratio as I am(4.88/33) with your 4.56/32 combo... and as you can tell... I love it!!!

 

you really only got 11 mpg???? with my current set up, 3.07 gears and 31 inch tires, i run 1840 rpm's at 70 mph, it needs gears bad, and when i plugged your transmission and your 3.55 gears and 33" tires in, you were running 1898 rpm's at 70 mph, so a little bit higher rpm's than mine but pretty much the same. but i have been averaging 18 mpg......the only thing i can think of is the more controled and timed shifting of the manuel and the fact that i have only 31x10.50 of rubber to push and you had 33x12.50 to push.....