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4.56 or 4.10's....what to do

Jeffro600

NAXJA Forum User
Location
Cheyenne, Wy
Im currently running 31's with stock gearing on my 93 XJ(4.0, 5 speed) and am getting ready to re-gear within the next week or two. With all the info ive collected, i think i can do it myself with a little bit of patients and alot of free time. Anywho, ill be running the 31's for a while longer till i can save up enough cash to do a larger lift, an SYE and 33's. Will 4.56's be too much gear for extended highway sessions with the 31's?? Will 4.10 be enough for 33's or will i notice that much of a difference with the 4.56's? Alot of the trails i frequent are a good ways down the highway(maybe 30-50 miles one way) and if the 4.56 will kill my mileage, i might just go with the 4.10s. Im thinking with the trails that i do(lots of rocks, slow crawling, lots of use of low-range) that ill be happier with the 4.56's...im just worried about excessive RPM's on the highway. Sorry for all the questions...Anyone have any thoughts or input?
 
I went with 4:10's as I was running 31's at the time and did not plan on going with 33's. Now I have 33x10.50's and added a transmission cooler and throttle body spacer and still have enough power to get down the highway at a decent speed and decent rpms. I am getting 18-20mpg on the highway with my current setup and couldn't be happier. You live in an area in WY where there are not a lot of hills so I would guess 4:10's will work for you.

Some may disagree, but that is what works for me.

Kevin
 
i'm running 4.88s and 31s right now with the 5sp, but will be going to 33s in the future. hopefully sooner than later. around town it is great. on the highway, i'm turning about 3k at 70. with the 33s, i'll be around 2700 - 2800 rpm. right in the powerband. engine purrs at that rpm. it will probably hurt my mileage, but will be great on the trail. plus, if i ever go to 35s, i'll still have enough gear.
 
Fuel90 said:
i'm running 4.88s and 31s right now with the 5sp, but will be going to 33s in the future. hopefully sooner than later. around town it is great. on the highway, i'm turning about 3k at 70. with the 33s, i'll be around 2700 - 2800 rpm. right in the powerband. engine purrs at that rpm. it will probably hurt my mileage, but will be great on the trail. plus, if i ever go to 35s, i'll still have enough gear.

Any idea what kind of mileage your getting at highway speeds with those 31's?
 
I have 4.10s with 33x1050. I live in flat land Ohio. They do good for me. If I were to do it again I would go 4.56. I have a hell of a time towing my boat with 4.10s. I average about 16MPG mostly in town driving. Since you do most of your wheeling in the rocks definitely go 4.56.

BA
 
Go with the 4.56, trust me, you will go bigger than the 31's eventually. Plus i lived with 4.56 and 31 for 6 months, no problems at all.
 
Jeffro600 said:
Any idea what kind of mileage your getting at highway speeds with those 31's?

I just regeared a couple of weeks ago, so i haven't had much time on the highway. around town i'm getting around 17mpg. i'd imagine around 14 - 15 at the higher rpm's. living in the mountains, the extra gearing helps out a bunch. i'm sure the next time i load the jeep down to go camping, the extra gearing will be great too. i think i could have done 4.56, but i just wanted a bit more when i factored in extra weight, drag, etc...
 
Jeffro600 said:
im just worried about excessive RPM's on the highway.

Your engine is not human, it does not have feelings. It will not cry if you run it at 3000-3500 rpm for extended periods. Keep it cool.

Your transmission will thank you.

HTH
 
Dirk Pitt said:
Your engine is not human, it does not have feelings. It will not cry if you run it at 3000-3500 rpm for extended periods. Keep it cool.

Your transmission will thank you.

HTH

Engine wont cry but you will when you gas it up.
 
Tough call, really. 4:10s will be more highway friendly with the 33's and 4.56 more trail friendly. Personally I'm going to 4:10's and 33's but then again there's a 4.7l (or bigger) stroker in the works so what I lack in gear I'll more than make up for in power that, and I want to keep the revs down with the stroker. Gearing choices need lots of thought and planning as to how they will fit into the BIG picture. Given you have the 5 speed, I'd probably lean towards the 4.56 to improve the trail use of the Jeep and live with a MPG hit. Then you have to concider the mts, for the most part any where you are going to wheel in this area you will encounter BIG grades going to and coming from the trail.

Bob
 
Rock Yacht said:
and I want to keep the revs down with the stroker.

What's the reasoning behind this?
 
The stroker combos we use around here tend to have their power band at a much lower rpm. The trick to good mpg is to put your cruising speed at a point where your engine is in its power band. More or less rpms don't necessarily mean less or more gas mileage. It all depends on matching your motor's capabilities, otherwise everybody would be running 2.73's for mileage.
 
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