Im still collecting parts for my build up and trying to figure out what gears I want to get. I already bought brand new 4.88s but might be thinkin 5.13s might be better for me, but Im unsure. If they are I could probably return my current gears and just trade them for 5.13s as they are the same price.

I have the 4.0 engine with the AX15 tranny and NP231 with JB Super Short SYE.

My YJ will have this:

SOA - waggy front spings, rear xj springs
Waggy Dana 44s
36-37 tires
detroits f&r
warn lock outs up front
front winch
full size rear tire
fuel cell, no back seat
traction bar
bla bla bla

My jeep is and will continue to be my DD for a few more years and it will see about 60% on road/40% off road. I drive mostly highway but only about 25 miles max a day (some days more some less).

The terrain I wheel in includes: Harlan, southern KY, hills, creek, some mud, some rock, East coast wheelin,

Do you guys think the 4.88s will be fine for me or should I get the 5.13s instead? Thanks

And yes Im still searching :flipoff2:

you wont like 513 on the freeway trying to do 75 mph engine will be revved pretty good if you arent on the freeway alot 513 are great if so stick with the 488's

Here play around with this..... Ive used it through every phase of my build ups.

http://www.grimmjeeper.com/gears.html


Getting back to your planned buildup however. I don't think you have ever driven a jeep like the one you are planning on the highway. I had a very similar build and my main priority was to keep it street legal and I still never took it on the highway. Id bomb around secondary roads with it, hell it could even get to 80+ MPH fairly easily, but it didn't belong going that fast, one little mishap or something jumping out infront of me had the possibility of being catastrophic.

-Unless you get expensive radials and larger diameter rims your tires are gonna suck ass at speed
-Your jeep even with sway bars will be scary at 75 mph if the motor can even reach it.

Go with the deepest gear you can unless you are going to run a 4:1 kit

Yeah, I dont plan on actually using the jeep that much on the highway as most of the places I go I drive on just main roads and such. It will be used on the highway but not that much if I can help it. By the time the build is done all my summer classes will be done so I wont have to use the highway at all really.

And according to that link you sent me to, the 5.13s would be slightly better for offroad but would be slightly worse on the road (cruising around at 55 or so - main speed I drive at). So Im thinkin that I will probably just stick to my 4.88s probably.

I plan on running some 37 MTRs with Kevlar or possibly some 37 Irok Radials.

Play with the calculators. I ran 4.88's with 35's and liked it. For my current build, I'm going to run 5.38's on 37 Iroks with an AX15. It's a trail rig, but I'll drive it to/from the trail. For DD, I have another vehicle.

Not all of us have DD's other than our jeeps :flipoff2:

I think for now Im gonna stick to my 4.88s and have them installed. I have a few friends who run both the 4.88s and 5.13s and prefer the 4.88s since they use their jeeps as DDs as well. I think I will be fine and satisfied.

The DD thing is relatively new for me. I had someone kind enough to pull out in front of me a few months back and total my Unlimited (went airborn and rolled). I made out good on the settlement and was able to buy a DD, strip my jeep and pick up a cheap XJ to build.

Suprised the others don't like the gearing of the 5.13's on 36/37's. Most of the guys I wheel with run 4.88's with 35's and 5.13's with 36/37's and love it. And yes, the jeeps are their DD's with a good daliy commute.

i drive mostly highway but only about 25 miles max a day (some days more some less).

yeah, i dont plan on actually using the jeep that much on the highway as most of the places i go i drive on just main roads and such.

huh???

Im currently in summer classes at college. The only way to get there is the highway which is about 10 miles or so each way. Those summer classes end in late july. After that, no more highway or very very minimum use of the highway.

Whenever possible I dont drive on the highway but when you have school 4 days a week you have to.

Understand? Sorry I cornfused you. :grinpimp:

Stick with the 4:88s you got them allready will be just fine for what you want to do and the pinion stay's larger with then as opposed to 5:13's just another plus in what you got on the shelf plus if you do an engine swap your still good have no fear and carry on :D

I run 5.13s with 35'' boggers and it is fine on the street. I went with the 5.13s because i will be going to 37s soon. I am not sure why everyone thinks 5.13 arent good on the street. Here in upstate NY there are lots of hills so the low gears are nice there is a lot less shifting down to pull long steep hills

Because most 5th gears are worthless without a V8 in jacked up rigs with large tires and since even with 4.10s a tranny in 4th gear (1:1) will be making the engine turn some pretty good RPMs at highway speeds (65-80 mph).

4.10s in 4th gear with 35" tires turns 2500 RPMs at 65 mph
4.88s in 4th gear with 35" tires turns 3000 RPMs at 65 mph
5.13s in 4th gear with 35" tires turns 3200 RPMs at 65 mph

Id stick with the 4.88s for reasons of strength, since you have them, and the fact that since you are still driving it it would keep your RPMs a little lower when cruising the highway. Plus if you ever get a 4:1 kit your crawl will still be acceptably low. At that point its your transmission thats holding you back without the first granny gear.

Had 5.13s and 37s and a 4.2 and it would barely run 55.

Those rpm calculators are great assuming you have the power to get going that fast.

I vote go as low as you can and stay in the slow lane

My XJ 4.0 with 37 MTRs is my DD. I run 5.38 in my waggy 44s and I can do 74 on flat land maybe a bit better down hill or with a tail wind dose fine on the rubicon and on highway 80

my vote 5.13's at least that low, if you are going larger than 35's. I have never been geared too low...many times wanting lower gears

Don't forget this as well as it seems alot of people seem to think the opposite.

-The deeper you go in gearing the more top end you lose naturally and the more shifting you have to do because the gears are alot closer together. 5.13s are probably a blast around town, I don't think I would want them on the highway

-Deep gearing DOES NOT equal horsepower, you will still lose it somewheres. Puting lower gears into your rig just brings it a little closer to where it was prior to larger tires.

-Your 5th gear will be worthless pretty much. Even with a stock TJ and 3.07s I had to downshift to get up steep grades on the highway. Now add a heavier vehicle, large 37" meats, higher COG, your 4th gear will be your highway gear. Your 4.0 has great HP but not alot of torque so unless you want to be revving the shit out of your engine If you can cruise along at 65-70 mph then you should consider that your goal and if you can actually do it then lucky as well.

5.13s.
I have 38" TSLs with 5.38s, but I plan to go bigger tire in the future.

if you are even thinking of switching do it, or you will be sorry later. it just like buying tires. anyone that has tried to decide 33's? or 35's? and went with the 33's regret it. always go bigger!