mattphillips90

I know the 4.56 will give you better power and I know that 4.10s will give you lower rpms at highway speeds but which one will give you the best mpg for city driving?

Broncs

For city driving I'm just not sure it will make a worth while difference between the 2 I drove around for a long time in an FSB with 4:88 and didnt notice enough of a difference to matter.

mattphillips90

haha fsb's are so big they can pull 38's without noticing a powerlose

2KXJJEEP

since u have a AW4 and running 35 u need 4.88 gears

VTJeep

Thought you were leaving?

mattphillips90

Uh oh, someone got caught

Gorillaxj

Honestly, I think 4.10's would be garbage and not a big enough change to be worth the $$ with 35's and an auto...

I have 4.56's and 35's. I wish I would have done 4.88's for the extra rpm/TQ up canyons and when loaded with gear. but the 4.56's do the job with no complaints.

City driving is hard to really gauge, with lots of stop and go it would be nice to have deeper gears taking some load off the motor during acceleration from a stop.

I would do 4.56's or 4.88's. 4.88's would be better IMO. I have never seen someone complain about to low of gearing, only to high...

mattphillips90

Wouldnt 4.88's cause me to have really high rpms on the highway?

Gorillaxj

all done with a 35" tire based on this calculator with a .75 over drive(AW4) suggested range for a 6cyl is 2000-3000 rpm, I think 2200-2500 is ideal.

4.10's at 70mph
Your RPM is about
Automatic With Overdrive 2,029
5 Speed 2,304

4.56's at 70mph
Your RPM is about
Automatic With Overdrive 2,245
5 Speed 2,551

4.88's at 70mph
Your RPM is about
Automatic With Overdrive 2,396
5 Speed 2,723

Juan4you

I have 4:10, only cuz the D 44 came with it. So when I locked the D 30 I bought gears to match. No problem wheelin in Johnson Valley. A mix of sand and boulders. Gas wise, nearly the same with stock gears and 31". I do enjoy cruising the freeway at about 2700 rpm. Checked out a link here and when I lock the rear I might go 4:56... 4:88 freeway rpm are too high. The chart shows 4:56 to be a well round number for 35's-wheelin and dd.

Juan4you

wow. Completely different from the one I checked out. Don't remember what its called but it showed 4:88 to be at 3800 rpm 70 mph. I'll try and look for it.

CheapCherokee

neither, go 4.88s. dont be scared to cruise at 2800 rpms on the freeway. your mileage will not be as bad as you think. if you drive lots of hills the lower gearing will be more better as you will not have to down shift nearly as much

holycaveman

Another for 4:88's The research I have done shows its best.

I have 32's and I will be running 4:88's if that tells you anything.

Lucky for us we have overdrive

Gorillaxj

they are all different... kind of annoying but its all based on what gear and what that ratio is.... some are 1-1 or 3rd gear in a 4 speed auto, or 4th in a 5 speed manual. some will list it in OD and some don't, you have to read the fine print to understand the chart. but even with that said they are all different lol

the AW4 based on two web-sights is 0.75-1 in OD. most charts with 4.88's are saying 2400-2800 rpm at 65...

for example this chart...
http://www.summitracing.com/expertad...d-Tire-Height/

this chart based on a 1-1 setup or 3rd gear in an auto
http://jeeptalk.org/gear_chart.php

4.88's and 35's is 3045 RPM, in OD or 4th gear its lower (0.75-1 ratio) 3045 - 25% = 2283.75 RPM (again this is all a mathematical guess) as actual tire height is unknown my 35's measure to be 34.1" tall, so its not really a 35" tire... and would cause a slightly higher rpm...

at the end of the day with 4.56's (which works fine) I could still bump the RPM and not every think twice about it, which is why i wish I had done 4.88's. but the difference between the two is not nearly enough to worry about or spend money on. if your worried about 4.88's then do 4.56's. I just wish I went a little lower.

CrawlerXJ

32" and 4:10 on XJ.