Help deciding which gears are better for me???
01-19-2013, 01:07 PM
#15
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I have a six speed 12 w 37's and 4.88's
I wish I had 4.56 I shift through the gears fast and on the hwy will be in 6th wishing I had another gear. Mpg is 16 around town and 18 on hwy
I wish I had 4.56 I shift through the gears fast and on the hwy will be in 6th wishing I had another gear. Mpg is 16 around town and 18 on hwy
01-19-2013, 01:29 PM
#16
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My 2012 JKU Rubicon auto has 4.56 gears with 35" tires which measure 34". The 4.56 gears are almost too much on the highway at 70 mph because I'm running about 2600 rpm which is higher than the green ECO marks on the tach.
Unless you are going to run a 37" tire, do a lot of towing, don't drive on the highway much, or live in the mountains where you have a lot of hills to climb at highway speeds, the 4.88 gears will be too much. Your rpms will be higher and your gas mileage will be less. The higher the rpms, the more fuel the engine burns which reduces your mpg. 4.88 gears will cause your engine to run at even higher rpms than 4.56 gears.
Unless you are going to run a 37" tire, do a lot of towing, don't drive on the highway much, or live in the mountains where you have a lot of hills to climb at highway speeds, the 4.88 gears will be too much. Your rpms will be higher and your gas mileage will be less. The higher the rpms, the more fuel the engine burns which reduces your mpg. 4.88 gears will cause your engine to run at even higher rpms than 4.56 gears.
Last edited by bo9roadking; 01-19-2013 at 01:36 PM.
01-19-2013, 03:01 PM
#17
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My 2012 JKU Rubicon auto has 4.56 gears with 35" tires which measure 34". The 4.56 gears are almost too much on the highway at 70 mph because I'm running about 2600 rpm which is higher than the green ECO marks on the tach.
Unless you are going to run a 37" tire, do a lot of towing, don't drive on the highway much, or live in the mountains where you have a lot of hills to climb at highway speeds, the 4.88 gears will be too much. Your rpms will be higher and your gas mileage will be less. The higher the rpms, the more fuel the engine burns which reduces your mpg. 4.88 gears will cause your engine to run at even higher rpms than 4.56 gears.
Unless you are going to run a 37" tire, do a lot of towing, don't drive on the highway much, or live in the mountains where you have a lot of hills to climb at highway speeds, the 4.88 gears will be too much. Your rpms will be higher and your gas mileage will be less. The higher the rpms, the more fuel the engine burns which reduces your mpg. 4.88 gears will cause your engine to run at even higher rpms than 4.56 gears.
Just to throwing this out there, those ECO marks on your tech, kinda went out the window when you lifted your jeep (less aerodynamic)/ put a heavier wheel and tire combo (more rotating mass). Honestly its better for your drivetrain because of the less amount strain put on it. More mechanical advantage causes less wear on the clutches and bands (high gears cause more friction because of more force being applied to do the same job) in your trans which keeps it running cooler (so less fluid and filter changes). Also, you drive a jeep, having a lil bit lower gear helps, especially if you actually wheel your jeep. And 300 rpm at 70 might use 1/100th of gallon more a mile, but like I said the more mechanical advantage could actually equalize it or actually improve your gas mileage. The lower the RPM is not always the better.
Last edited by iwaxmyjimmy; 01-19-2013 at 03:07 PM.
01-19-2013, 03:05 PM
#18
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What was your gas mileage with stock tires? because that is pretty much what I get with a stock (for a week longer) 2010 Rubicon.
01-19-2013, 03:42 PM
#19
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Just to throwing this out there, those ECO marks on your tech, kinda went out the window when you lifted your jeep (less aerodynamic)/ put a heavier wheel and tire combo (more rotating mass). Honestly its better for your drivetrain because of the less amount strain put on it. More mechanical advantage causes less wear on the clutches and bands (high gears cause more friction because of more force being applied to do the same job) in your trans which keeps it running cooler (so less fluid and filter changes). Also, you drive a jeep, having a lil bit lower gear helps, especially if you actually wheel your jeep. And 300 rpm at 70 might use 1/100th of gallon more a mile, but like I said the more mechanical advantage could actually equalize it or actually improve your gas mileage. The lower the RPM is not always the better.
If your comments were meant for me, I'm not worrying about my gas mileage. It went out the window when I put on my ProRock 60 and PR44U during the 4.56 gear change. I'm also running full underbody skids, sports cage, sliders, and full width front and rear steel bumpers with a 12.5k winch. I also have ATX Slabs and getting ready for 37" tires. All of the weight and rotational mass definitely don't give me great mileage and I don't expect it too. Also, since I have a Rubicon, my 4:1 transfer case makes up for having more streetable gearing for a daily driver. It is not an issue to put my TC in low and crawl.
Last edited by bo9roadking; 01-19-2013 at 03:54 PM.
01-19-2013, 04:07 PM
#20
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Yeah that 4:1 tcase is bad ass aint it? And those were just general comments to get good solid info out there for some people who either haven't got the experience, done the research, or just even thought about how gearing affects your jeep.