31" on 4.56

[winkosmosis]

But I don't think ANY XJ ever came with 4.56 gears

 

[1990heepxj]

no there was a rare few that actually did, lotsa specialty stuff on them i dont remember exactly i came across the info a month or so ago on the web. ive found plenty of stock 4.10s in the jy's lately.

also if ur topping out at 70 or 75 or taking hills in 5th ur for sure over geared a seriously large amount. i bet u take off like a bat outta hell if urs is as i said. i know i was obviously speeding it was just to see what it topped out at but mines on 3.73s and 33s atm and my xj did 100 on its own steam no down hill and mines set right at about stock now. im actually going to be getting 4.10s for my 8.8 and d30 next weekend so ima lose some speed but do what i orig wanted have better mpg around town since its 90% of my driving. 4.10s ill have power to chirp gears if i want and still fly down the freeway with any pace of fast traffic i find here on socal freeways

see my issue with topping at 70 is my xj is about 5.5 lift but is my dd and very smooth to drive. if i need to drive on freeways often i could and i dont like being restricted to the slow lane and i know the 15 freeway is very often much faster then 70. so i say if u like lotsa low end torque and dont mind 70 mph max then thats cool that works for u im glad ur happy with it, its just not my prefrence for my dd to be like that.

 

[ILLXJ]

The only XJ's that came with 4.56's were the 2.5L/AW4 combo, mainly on 87-89. Most had a non-c-clip D35. JIM.

 

[90 waggy]

was an 87 sitting in a field for 10 years. we raped her for all she had. which wasnt much. i dont imagine the dana 35 will last long with 33's and a tired small block. :greensmok it didnt look like a dana 35 though so i dunno...my buddy has them...well see

 

[1990heepxj]

if 87-89 then it could only have a non c-clip d35 or that rare d44. i ate an axle shaft on my d35 first trip to cougar buttes so i now have an 8.8. d35 lock right and 33s equals shaft snappin action. it would be a special xj to have those 4.56s.

 

[Darky]

I can cruise 75 with my 4.88s and 33s, which according to you is overgeared 1990heep...Te way I look at it is that the speedlimit in CA is never higher than 70 (not that I've seen at least, and I've been all around this place), worrying about being able to do 90 is foolish. If you're worried about mpgs at all, getting up that fast will kill it quick, aero drag increases exponentially with speed. 4.56 with 31s is a little deep, but it's not bad. I had a friend who drove it for years before getting 32s. It had great power and torque and he could do the speed limit everywhere we went.

 

[ktm racer 419]

Are you guys with the deeper gears factoring odo error into your mileage calculations? You really drove a lot shorter distance than your speedo says

+1, it's either lack of a recalculated speedo or some of these guys with lifted, big tired, overweight, low geared Bricks on wheels are defying the laws of physics! :eeks1:

Some of these guys are getting better numbers than I was getting with my factory (Stock) new 4 Banger equipped early 80s XJ.

im seeing it as the same thing. noone is factoring in the fact theyre doin alot less miles then the odo will read.

i know how to do math

and i verify it using the gps

every trip i take i check my fuel mileage. ive made a habit of it.

 

[ExTankerGuy]

I ran 4.56 with 31s for about a year. I thought it was awesome! Prolly the best MPGs I ever got with my Jeep!

 

[1990heepxj]

darky u cant deny that its over geared the numbers techically proove it, but thats how u like urs to be setup and it works for you. also dont take me wanting the top end as i wanna do 90 everywhere, im saying that time early in the morning when the freeway is haulin ass i would like to be able to keep pace is all. so 4.10s 33s and a manual trans ill have alot of low end torque and still a plenty high top end. ill be happy with my 4.10s just like u are happy with ur 4.88s. its all about personal preference i think the only gearing that will hurt u is undergearing so anything above is just what ur comfortable with.

 

[ExTankerGuy]

You won't like it. 4.10 and 33s will still suck!

 

[90 waggy]

You won't like it. 4.10 and 33s will still suck!

ya with an automatic...standards are a little lower geared. my 4.10's and 31's with the auto is somewhat lacking right now so i might just regear. but i dont do over 65 anyway. my friend with 32's and my old 3.55's and a 5 speed loves the way it works. to each is own on this one. happy trails :cheers:

 

[srmitchell]

I ran 4.56 with 31s for about a year. I thought it was awesome! Prolly the best MPGs I ever got with my Jeep!

Good to hear. Im only going to 265/75 which are barely 32's.

 

[1990heepxj]

na im on 3.73s atm on 33s and its pretty nice but i wanted 4.10s so im finally gonna get them. on 3.73s im at stock performance with a manual and i want a bit more but not too much for my taste

 

[winkosmosis]

I thought the manual was geared taller so it needed a shorter axle gear

 

[1990heepxj]

the manual has lower gear ratios thats why a 4.0 manual starts with 3.07 and a 4.0 auto starts with 3.55s. so u gear accordingly one ratio lower for an auto then a manual

 

[Mike H.]

umm, yes, my speedo is corrected, and, my 100% stock WJ shows the same milage on my weekly 440 mile round trip.
4.56's, 33x10.50's, 5spd, 4.0, lots of armor, 2.5" lift, clean roof 18mpg at 70-75mph... 20+mpg at 65mph... and, it'll still go plenty fast... 95mph last week while passing on a 2 lane hghway and still climbing good (for what it is).

You start lifting it high, running wide tires that stick out way past the fenders, cluttering up the roof, run a spare off the bumper then milage will suffer.
Mine has none of that and is in tip top mechanical/electrical condition.

 

[Justpunchit]

I am on 31 and 4.88 gears... I have no problems running 65-70 MPH.

I do not wish to drive much faster than that. You will be fine on 31 and 4.56 for a year.

I know there's alot of veriables but what you getting for mileage? I'm hoping with my setup (33's/4.88's) i should get like 18mpg.

 

[89xj]

must be personnal preference, but for my lifted jeep with the 4.0, 5spd, and 31" tires, i prefer the 4.10 gearing it has.

 

[JAS]

I can drive 75mph all day long with 31" tires and 2" lift. Your problem is being overgeared

My lift is nearly double your lift. I can run that fast just choose not to.

If you run in flat lands you can run 4.10 on 31s
If you have any mild hills you should run 4.56 on 31s
If you tow or live in the mountains then 4.88 is very doable.

It is a modified Jeep and not a 2 seat sports car.

 

[JAS]

I know there's alot of veriables but what you getting for mileage? I'm hoping with my setup (33's/4.88's) i should get like 18mpg.

I don't rightly know at the moment. I am in desperate need of a new exhaust. It is very leaky before the O2 sensors.

I just corrected the Odo, and have not run a full tank of gas through it. Even on a good year I only get 2000 miles on it per year.