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  #1  
Old March 26th, 2008, 14:55
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Muad'Dib Muad'Dib is offline
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4.56 gears at stock height stock tire size

Hello..

I probably have a really stupid question, but i dont want to have to re-gear more then once...

I have read all over the place to armor up and lock BEFORE you lift and change tire size to get a feel for wheeling, and a real idea of what height you want to go to.

My inital plan was to go with a 4.5" lift running either 32's or 33's. Seems that 4.56 would be the best gear ratio to go with at this tire size.

However, if i keep it at stock height, or more importantly stay with stock tires, then whats going to happen if i install 4.56 gears? I still want to be able to get "ok" gas mileage (not like its great now anyways) and on occasion be able to go 80 on the highway.

I was thinking about locking it with 3.55 gears, but thats seems stupid to waste money on lockers for a gear ratio i KNOW i wont stay at. Even IF i never lift the Jeep i would at least want to go with 4.10 gears.


What do you guys think?

Sorry for the stupid questions, but im still a big noob to gears \ tires \ lifts.
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  #2  
Old March 26th, 2008, 14:57
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bcmaxx bcmaxx is offline
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Re: 4.56 gears at stock height stock tire size

my 89 aw4 with 4:11's and 235/75/15's drove me nuts on the highway. The rpm was way up there, it was kinda fun in town though.
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  #3  
Old March 26th, 2008, 15:11
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Re: 4.56 gears at stock height stock tire size

The XJ was available with 4.56's from the factory, so it can't be all that bad. If you are staying with stock tires, I would recommend 4.10's. They are easily found in early 2.5L stick shift rigs. If you are doing a lunchbox locker, I would buy the axles and put the locker in yourself. No setup required.
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  #4  
Old March 26th, 2008, 15:21
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Re: 4.56 gears at stock height stock tire size

Although I think you're on the right track here, I'm not sure 4.56 and stock tires will be able to do 80mph on the highway.

You could throw an aussie in your axles now, build a seperate set of axles, and when you swap them in sell the ones with 3.55s and aussies.

I highly recommend small lift and lockers. You should see what you can do with just 31-32s and lockers, it's rediculous!! Sometimes you can do better than huge built rigs!
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  #5  
Old March 26th, 2008, 15:27
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Re: 4.56 gears at stock height stock tire size

It seems like your on the right track and you know what you want/need so kudos to that! The only thing is that I think most people recommend locking it after you get a feel of wheeling your Jeep. I personally wouldn't go to 4.56 gears without larger tires but I drive over 60mph daily sooooo...

I'd armor it, and then save for your lift/wheels/tires/gears/locker at the same time. Since I wouldn't run 4.56's now, I obviously wouldn't want to rip apart the axle twice so just do it all at once.
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  #6  
Old March 26th, 2008, 15:31
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Muad'Dib Muad'Dib is offline
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Re: 4.56 gears at stock height stock tire size

I was thinking more along the lines of arb lockers.... i guess thats why im so concearned about what gears to get now, so that when i DO lock it, and then decide to go with bigger tires and a lift, i dont wast my money on another set...

The problem with doing it all at once is having the money all at once... either that, or buy a little here and there and let it sit for maybe up to or over a year! Which is way too damn long for me!

Shit i have a CB i need to install that i got a month ago! Its been KILLING ME that i cant get it installed .. time constraints, vacation, kids every-other weekend, and weather.
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  #7  
Old March 26th, 2008, 15:41
FoMoCo FoMoCo is offline
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Re: 4.56 gears at stock height stock tire size

I say go for it, at 80mph it'll be turning ~3400rpm in overdrive which is ~100rpm lower than what it does in 3rd with stock gears, and it'll be absolutely bad ass around town and on the trail
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  #8  
Old March 26th, 2008, 16:10
Nomercy Nomercy is offline
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Re: 4.56 gears at stock height stock tire size



say ur running a 235/75R15 thats about 28 inches tall. now using the fith gear ratio of an NV 3550 which is .78 overdrive, with 4.56 gears at 2000 rpm your only moving about 47 mph. at 5000 rpm you will be able to do about 117 mph. to do 80 mph your running about 3500 rpm.

With an AW4 auto your RPMs will be slighty lower but just barely.

IMHO thats just to high. i have an 05 rubicon with the 6 speed which has a .84 overdrive and 4.10s and run a 33 and at 2000 rpm im doing about 55 and at 85-90 im hiting about 3000rpm. this set up is just about right for me cause it leaves plenty of power to turn those heavy tires even at highway speeds. if i were you id go with 4.10 and stay with those casue those will be about right.

with 4.10s and an overdrive of .78 at 2000 RPM you get about 52 mph on 235/75R15s at 28 inches tall. and at 3000 RPM you doing 78 mph, and have a top speed of 130 mph at 5000 rpm. i belive that the 4.10 gears are the better choice for the tire size your looking at.

Now with that being said if you think that you may want to go to 35s in the future and can live with the rpms then go with the 4.56 gears. your choice in the end, but now with the numbers i hope you can make a better more informed decision.

33 inch tires>>>4.56 gears
2000rpm=55mph
3000rpm=82mph
5000rpm=138mph


33 Inch tires>>>4.10 gears
2000rpm=61mph
3000rpm=92mph
5000rpm=153mph

i still say 4.10s

also something to think about is if you have a Dana 35 rear you may want to upgrade cause a D35 rear and 33 aint gonna last very long....
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  #9  
Old March 26th, 2008, 17:38
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Re: 4.56 gears at stock height stock tire size

I ran my 4.56s with my 235x75s (~29") for at least 5K miles before I got the 33s on. They really were not that bad. No problem doing 80 in OD, if you wanted to. Now with the 33s I tach a comfortable 2250 at 65 in OD--with the 235s it was more like 2500--a little busy, but certainly liveable.
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  #10  
Old March 26th, 2008, 18:00
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Muad'Dib Muad'Dib is offline
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Re: 4.56 gears at stock height stock tire size

Quote:
Originally Posted by Nomercy
lots of good info
So your saying i should be thinking about 4.10 gears with 32's or 33's if/when i decide to do so instead of 4.56?

Right now just with my 28/29's and 3.55's the 4.0 is a dog up hills. Its worse when towing. On flat land its super fast etc... I dont want this to be an issue when i re-gear.
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  #11  
Old March 26th, 2008, 18:25
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Re: 4.56 gears at stock height stock tire size

4.56s are perfect with 33s--I certainly would never go any higher. I had a full set of 4.10s and boy am I glad the fine folks on the board here convinced me to go 4.56 instead. Off road is great, and cruising at 2250 @ 65 in OD is perfect. Even with the extra couple hundred pounds of armor, passengers and wheelin' stuff it still easily makes this hills on the Interstate. If you think you'd ever go bigger than 33s, I would even consider 4.88s (if your rear axle allows).
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  #12  
Old March 26th, 2008, 18:53
Nomercy Nomercy is offline
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Re: 4.56 gears at stock height stock tire size

well if it were me id go with 4.10 i cant tell you what to do. no one but you can decide. with an auto 4.56 may be a better choice, generaly a lower gear set is better with an auto, easier to get it moving. but like i said its totally your choice. just look at the numbers and decide which is better for you and your needs.
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  #13  
Old March 26th, 2008, 19:00
Nomercy Nomercy is offline
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Re: 4.56 gears at stock height stock tire size

Quote:
Originally Posted by Muad'Dib
On flat land its super fast etc...
i just picked up an unmolested 01 cherokee sport with a 5 speed and was very surprised with the giddy up it has for a 4 liter. now i just gotta ruin it by lifting it about 7 inches and hogin in some 35s
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  #14  
Old March 26th, 2008, 19:01
T3hk1w1 T3hk1w1 is offline
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Re: 4.56 gears at stock height stock tire size

I believe that the Chrysler 8.25" has no carrier break, so if you have that axle you might just lock the rear and wait on the front or just get a lunchbox locker for it. Alternately, you might try finding a set of junkyard 3.73s, as they won't change your current RPMs all that much, and they are on the lower(numerically higher) side of the carrier break, so you can get a locker that will also run 4.56s when you decide to upgrade.

EDIT: or you could just put up with high RPM's, my Jeepster's V6 runs 2900 RPM at 65 MPH with the stock 3.73s.
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  #15  
Old March 26th, 2008, 19:05
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Re: 4.56 gears at stock height stock tire size

punch the numbers in here and you'll get some answers regarding speed and rpm.
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