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Discussion Starter · #1 ·
While I still have some time before my current tires are bald and need replacing, I'm giving some thought as to what to upgrade to. the choice is 35's or 37's. This is on my 03 Rubicon which has the 4.10's in the axles and the 4:1 Tcase and the 4 speed auto. It's still my DD and will be for some time still. It's not necessary to be crazy geared really as everything I generally do is mild to moderate. I have a 1 inch body lift and the RE 4.5" short-arm lift on and if needed I have 1 3/4" spring spacers I could put back on. So I doubt clearance is an issue for the 37's. Just wondering what the thoughts were on the gears. I'd assume it would put me in 4-lo more often off-road, but on-road would it be bearable? Mainly city driving for me.
 

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Fucking Zen as Shit
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With the auto and 4:1 t-case i personally wouldn't worry about re-geraing right away.

i was running my grand waggy with an Auto, 2.63 (whatever the 228 case is) and 2.73's in the axles with 35" tires and was never thinking i needed to regear off-road.... on road yes (but i got hella good gas mileage on the highway) i say go 37's with the current setup, wheel it and see what you think. I think it wont be too horrible myself
 

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Discussion Starter · #3 ·
That's kinda the way I'm leaning right now since the cost diff between 35's and 37's is practically nil. When i get to the point where its a trail only rig I'll more than likely re-gear though.
 

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Covered in mud...
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Install a trans temp gage. The auto will mask a lot of the lack of gearing, but you'll heat the hell out of your fluid.

I remember a test once, where they went from 3.08s to 4.56s and dropped about 100 degrees in trans temp(not on a jeep, but the concept is still the same..).
 

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Install a trans temp gage. The auto will mask a lot of the lack of gearing, but you'll heat the hell out of your fluid.

X87623486128937 toasted my tranny already because i

1) DID NOT regear
2) thought about putting a temp gauge in, but didn't until AFTER i blew the tranny
3) didn't provide extra cooling to compensate for the extra load.
 

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Me balls are huge
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I think its going to suck driving your brick in the wind on the highway with 37's, 4.10's, the amount of power you have, and an automatic that will want to downshift all the time.
x2

I have 33" tires and 3.73 gears on my TJ, and I hate it on the freeway. Going up the slightest grade requires downshifting to prevent slowing down. Now I drive with O/D off all the time.

I would love to have 4.56 gears.

If you go with 35 or 37" tires, and you want to use O/D, 4.88s are almost a must...unless you drive downhill all the time. :sonicjay:
 

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goofy
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I am not an expert.

I would strongly recomend re-gearing. If you do not want to, then turn over drive off. I dont think you will get much use out of the over drive anyway. Also the tran temp gage would be a good idea.
 

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Discussion Starter · #11 ·
I run 33's right now and probably have another 18months or so left before I need to replace them. I plan to put the tranny temp gauge in regardless, just haven't actually looked at one to put in or the work involved.

Since I plan on having an RV before year end and would be towing the jeep where ever I want to wheel it, I really won't have much if any highway driving. If I need/have to re-gear I'd rather only do it once. So, at that point it would become a choice over 35 vs 37's with regards to offroad need really and choosing gears accordingly.
 

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I have 37's on my tj. 4.0l, 5 speed, 4.56 gears. It's ok around town, but 5th gear on the highway typically won't hold speed up hills. I would go with at least 4.88's if I ever redid it. Won't really matter if you are going to tow it around though.
 

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in my opinion, the gearing is almost more important when offroad than on the street. on the street your tires are aired up, and you "generally" don't put as much stress on it as wheeling.

offroading, you got the drag of the terrain, low pressure tire making ur tranny work harder, and less airflow due to low speed driving.

on my wifes jeep i went with 4.56 on 33's, so she has a little extra up and go and nice wheeling gears, and will still be happy if she wants 35's. on my jeep i'm gonna go straight to 4.88 on 33's, so i have better off-road gears, options in tire sizes, and just live with the top speed sacrifice. BTW, both of these jeeps are daily drivers.
 

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Can't lose with 42s
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eh id just leave it alone...gears and installs are expensive as hell and you already have factory 4.10s..lotta money for a lil more gear
Like someone else mentioned, just turn OD off and it should be bearable

my setup really needs gears, I've got 3.07s, locked front and rear a 435/208 and 35x16 boggers...yeah mine lives in 4lo

X900 on the tranny temp gauge...Autos hate heat!
 

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AAA GOLD ROCKS!!!!!
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4.10's with 35's and a 42RLE will suck. The 42RLE hate heat. You will not be able to run the OD. Trust me I ran them for 4 mths then regeared to a 4.88.
 

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go w/ 4.88's

i had 4.10's w/ 35's and a 3 spd auto; it sucked!

i am much happier w/ the 4.88's, even w/ only s spd tranny (would rather have a 4 spd though)
 
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