xj_mudder

Hey everyone, i have a 99 cherokee lifted 4.5 inches on 33x12.50's, and its my daily driver, and im looking to improve my gas mileage. just wondering what a good gear ratio would be for highway driving without sacrificing a lot of torque? i still want it to do good in the mud pits or a little bit of minor rock crawling though. just wondering, any help would be greatly appreciated

Donnie_K

What tranny do you have? I'd be looking at 4.10's with the AX-15 or 4.56's with the AW4 if I were to run 33's.

xj_mudder

AX-15. ive heard 3.07s arent too bad. so you recommend 4.10s?

EvstaG

If you want a cheap way to get yourself closer to the stock gearing, you could go to the junkyard and find an auto Cherokee with the 3.55's. (Most common gearing on Cherokees by far, shouldn't be difficult to find.) This will probably not be the ideal, ratio but will be an improvement over what you have, and should be cheap. If you drive primarily on the highway, and spend little time on the trails, then this may be a good gear ratio for your needs. However, if this is a trail rig that you just use the highway to get to, it may be worth investing in some lower gears.

xj_mudder

i dont mind ordering gears online. im just looking to get the best ratio possible thats a little more highway friendly without sacrificing too much torque. like i said its my daily driver, but also a trail rig for weekends and a few days after school

cruiser54

3.07s would suck.

MountiansRcool

go with 4.10s !!! i have 4.56s 33's and a manual tranny, i love it, but on the highway it maxes out at 65 and the rpm's are very high, but it is geared extemely low, i can go in 4th gear going 25 mph up steep inclines and my 5th gear gets torque att about 45 mph

salad

3.07 is stock for 4.0L/AX-15 equipped XJs. I would also recommend 4.10 to drive 33" tires. 65 MPH will put you around 2100 RPM in 5th gear. It's a little deeper than stock, but you do need a bit of extra oomph to spin those rubbers. You may actually end up using less throttle.

Check this out: http://www.grimmjeeper.com/gears.html

EvstaG

If you are fine with buying gears, I will X2 Salad ^^, and previous who have said the same.

mr white

3.07s are stock...
If you want gas mileage put the stock tires back on and lower it.

cruiser54

Lower cruise rPM does not guarantee better mileage. Try this. Buy one of these and install it on your dash in plain view. Drive so that the vacuum always stays as high as possible.

opake

I've got a 96 with the AX-15 and 31s, I swapped to 4.10s in preparation for 33s. The 4.10s and 31s are definitely fun, first gear is kind of useless, but I can cruise at 70 on the highway under 3k RPM. For 33s I think 4.10s will be great, especially for a daily driver. I swapped my speedo gear out to be correct as well and calculated mpg is 15-17 with 4.10s and 31s. (I granny shift, truck rarely sees 3k RPM).

99 Purple XJ

What cruiser said its a good idea i have a vacuum gauge the higher it reads the less work the motor is doing resulting in better gas mileage



Very simple to install and work nicely

Opake i run 35s on 3.55 gears and when its raining i dump the clucth at 3k spin in 1 st gear slam 2nd gear and still spin lol its alot fun

salad

Nice. You just run a vacuum line into the cab yes?

Also, your signature makes me sad. Reminds me of that clown with the ambulance in the Craigslist thread that he's too lazy to get a title for.

99 Purple XJ

Yup just one line in the cab very simple when i get home ill post a pic of how to tap into the vacuum line to get it work