hawkswag1 Posted March 11, 2014 Share Posted March 11, 2014 I just installed my 4.5 inch rough country lift kit. Had to fabricate the shackles to be an inch taller because my springs were very worn. I will be running 33s in a day or two opposed to my current 30s. What type of gas mileage should i be expecting? I get around 15 with my 30s. Also i have heard that some junkyard axles have gearing that could be swapped with comanches for better gas mileage, which would be best? I have a 4.0. I will be driving back and forth from school and work which is just around town. Thanks! Link to comment Share on other sites More sharing options...
Pete M Posted March 11, 2014 Share Posted March 11, 2014 auto or stick? Link to comment Share on other sites More sharing options...
AeroNautical Posted March 11, 2014 Share Posted March 11, 2014 Does rough country make an MJ lift kit? Or did you buy a cherokee lift? If so, than the shackles would have been too short to work with an MJ without fabrication anyway. Otherwise, that's alot of sagging. What is your current gearing? If you don't know, let us know the transmission you have? Link to comment Share on other sites More sharing options...
Zebvance Posted March 11, 2014 Share Posted March 11, 2014 I'm running 32's with a auto 4.0 and 4.10s and it needs more. I'm lifted quite a bit though and head winds are not my friend. I would suggest 4.56 gears for it. 4.10s to get by though. Link to comment Share on other sites More sharing options...
wvzj Posted March 11, 2014 Share Posted March 11, 2014 My MJ has 32's and 3.55 gears with the auto it's not bad, But plan on going to 4.56 once the ZJ is finished. I think I was getting 15-16 mpg with that setup. Really depends on your tranny and intended use Link to comment Share on other sites More sharing options...
Incommando Posted March 11, 2014 Share Posted March 11, 2014 What is acceptable to some will not be to others and has a lot to do with how you will use your truck. I had no problems on road or off with my '88 auto with 32's and 3.55's. I honestly think that I hit it harder off-road in it than the majority on here do, as well. Badlands, Haspin Acres, 491 were all parks I hit and I didn't shy away from anything that any other similarly tire-sized vehicle went on. I would have preferred lower gears and they were on my to-do list but we do not have the type of technical rock climbs and the like that make them absolutely necessary. Play with your numbers here: http://www.grimmjeeper.com/gears.html Link to comment Share on other sites More sharing options...
hawkswag1 Posted March 12, 2014 Author Share Posted March 12, 2014 Its an auto. Ax-15 i believe that is. My vacuum system is completely screwed up due to the fact that when i found the truck a rat had eaten through all of the lines. Its doing fine with the 33s on. And i do go wheeling about every other weekend. I just want to save some gas if possible. I know some say i shouldnt complain if i wanted bigger tires but I'm only a highschool kid and i pay for my own gas Link to comment Share on other sites More sharing options...
hawkswag1 Posted March 12, 2014 Author Share Posted March 12, 2014 And yes rough country does make and mj lift kit but they are idiots and send you the same shackles as the xj lift kit and expect you to be happy with it. Link to comment Share on other sites More sharing options...
hawkswag1 Posted March 12, 2014 Author Share Posted March 12, 2014 An. Excuse my typo Link to comment Share on other sites More sharing options...
Pete M Posted March 12, 2014 Share Posted March 12, 2014 AX-15 is a manual. AW-4 is the automatic. your gas mileage will be what your gas mileage will be. results will vary, but it will likely get worse no matter what you do now. 33s are harder to push around, plain and simple. but there's no sense in worrying about your mpgs. just drive it like an old man and you'll be ok. :thumbsup: but make sure it's running to its full potential. do a tune up if you haven't already and fix the vacuum lines. :thumbsup: Link to comment Share on other sites More sharing options...
mvusse Posted March 12, 2014 Share Posted March 12, 2014 My daughter runs 32s in her 4.0 Cherokee. Automatic transmission, 4.10 gears, 4.0 HO engine and a reflashed CPU (done by previous owner 10 years or so ago) and the thing is stupid quick. Breaks loose the rear tires no problem when stomping on it from a still stand. I ran 33" street tires on my Renix 4.0 with the stock 3.55 gears with an automatic transmission. Mileage wasn't terribly bad. Actually, 70 to 85 mph it was better than with the stock 29" tires. Aggressive MT tread will definitely affect mileage more. I later ran 35" MT tires with the same stock gears and overdrive was pretty much useless. MPG took a 25% hit too. I currently run 37" tires on 4.10 gears, but the engine is old and tired now. It will move them, but no better than my 2.5 on stock tires. Plan is for a stroker and deeper gear, but lack of $$$ is stopping me. Link to comment Share on other sites More sharing options...
Usamedic Posted March 13, 2014 Share Posted March 13, 2014 Mpg is so dependent on how you drive, and understanding your transmission. Often I'll leave my my aw4 in drive instead of overdrive and find that I'll get slightly better mileage because the truck isn't working as hard. It's the same with most yj's fifth gears. The engine struggles in fifth and your mpg drops. Get the tires on their and drive it, then decide if you can drop the gearing. I know on one of my yj's I went from 4:10 to 4:88s and got better mileage accross the board as the engine/tranny/ and gear combo worked better for most daily driver conditions Link to comment Share on other sites More sharing options...
benjy_26 Posted March 13, 2014 Share Posted March 13, 2014 I have 32" KM2's on Canyons with a locked 4.11 rear end and I can sit therr and spin them til they pop. The condition and tune of your engine will play a big role in how much gearing you will need, as well as your intended use. If you have a big lift, headwinds (and crosswinds) WILL be a factor. Myself, I have a 1.75" lift and a lot of cutting to fit those 32's. Also, if possible, get yourself a set if nice, light wheels. I got a whole lot more power (according to my highly calibrated @$$-o-meter®) by going from my 27lb steel 15x7's to my 16lb 15x8 Canyons. Rotating mass and unsprung weight are things we as Jeepers sometimes ignore, but they affect us in a big, big way. Link to comment Share on other sites More sharing options...
benjy_26 Posted March 13, 2014 Share Posted March 13, 2014 My daughter runs 32s in her 4.0 Cherokee. Automatic transmission, 4.10 gears, 4.0 HO engine and a reflashed CPU (done by previous owner 10 years or so ago) and the thing is stupid quick. Breaks loose the rear tires no problem when stomping on it from a still stand. I ran 33" street tires on my Renix 4.0 with the stock 3.55 gears with an automatic transmission. Mileage wasn't terribly bad. Actually, 70 to 85 mph it was better than with the stock 29" tires. Aggressive MT tread will definitely affect mileage more. I later ran 35" MT tires with the same stock gears and overdrive was pretty much useless. MPG took a 25% hit too. I currently run 37" tires on 4.10 gears, but the engine is old and tired now. It will move them, but no better than my 2.5 on stock tires. Plan is for a stroker and deeper gear, but lack of $$$ is stopping me. Maybe a stock rebuild on your 6 banger and a pair of Super-doody axles from the JY woukd make your Jeep happy on 37's. I've seen a TON of F250's around my area with both axles intact. Some come stocm on 4.88's and the local pick and pull sells ANY axle for a Benjamin around here. Maybe I need to build a truggy.... :D Link to comment Share on other sites More sharing options...
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