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R/Tless...for now
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Discussion Starter · #1 ·
Had my first highway drive with the 265/75's and the trans did a good bit of hunting with the stock 3.55 gears. So I'm thinking about gears, but was wondering what kind of rpms and mileage folks are seeing with 4.10s or 4.56s and 32" tires?

Eventually I know I want to go up to 33's, so I'm thinking 4.56s are the way to go, but I'm wondering if that will be too much with the 32s. Right now I'm only seeing about 2k rpm at 70-75mph with the 3.55s, so a bump probably wouldn't hurt too bad, and would help keep the trans from constantly downshifting, which may improve gas mileage overall.

I already have a set of 4.10s for the 9.25, would just need to get a set for the front. Altho, I could also sell those and help finance 4.56s.
 

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lost in translation
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im taking it that your talking about the 4x4 with 33's?i think mine are 26's or 27's,and in od im hitting right around 2500 maybe 2700 for 65-70,dunno if it makes a difference but im in a ram as well,and stock size tires..(16") rims
 

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Professional Slacker
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I've been told If I do a gear change (01 QC 3.55 265-75R16) I should go with 4.10's... but for the price I could go 4.56's..

Try out the 4.10's I guess since you have one already and tell me how it goes.. I don't care personally about the MPG because mine are none existent as they are.
 

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With 32's and your wanting 33's in the future, I say 4.56's, they don't effect your RPM's too much even at highway speeds.
 

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Loud is NOT Fast
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1,768 Posts
If you do not intend to use your 4WD right now, I would say swap in the 9.25 with the 4.10s and see how you like it. If it works for you, then go with 4.10s up front. 4.56's will make for better in town mpg, but MAY hurt highway mpg. Altho, with 32/33's or larger it will probably help.
 

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if you want to go to 33's then go 4.56's and get the tcm out of a jeep gc to get your 5th gear and you should be fine and i second the try the 4.10's since you alredy have them. i plan on 4.10's since i cant stand bodylift gaps and cant afford a rancho kit lol. and my 32" mudders seem to get the job done pretty well. and my truck also rocks the cali lean ass heavy look.
 

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R/Tless...for now
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Discussion Starter · #8 ·
Thanks guys. I think I'm gonna go with the 4.10s and skip the body lift. Then when my highway driving is done, just do new wheels with 32x11.50R15 Mud's. Should be enough for the wheelin' that I plan to do.
 

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.:.:.:.:.:.:.:.
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You might try doing the Jeep TCM swap anyway. It holds the TC lock much longer than the stock TCM does and gives you the 5th gear to lower your RPM a bit more. If you run the highway alot, do 4.10's. Flat ground at 65-70 mine shows right around 18mpg (instant), roll in the throttle at all and it's down to 12-13.

I turn 2000 at 60 with my 32's and the Jeep TCM with 4.56.
 

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R/Tless...for now
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3,332 Posts
Discussion Starter · #10 ·
You might try doing the Jeep TCM swap anyway. It holds the TC lock much longer than the stock TCM does and gives you the 5th gear to lower your RPM a bit more. If you run the highway alot, do 4.10's. Flat ground at 65-70 mine shows right around 18mpg (instant), roll in the throttle at all and it's down to 12-13.

I turn 2000 at 60 with my 32's and the Jeep TCM with 4.56.
Interesting, hadn't heard that about the TCM. What year Jeep do I need to look for?
 

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just a quick thought. my truck has 3.92's and a 3.9 v6 so it may be diferent with your set up.

I put my 265/75r16s (just a we bit under 32's) on and noticed some gear hunting. when I got home i adjusted the tire size with my superchips 3815 to adjust the speedo, but it seemed to fix the tranny hunting for the proper gear as well.

If this where to work for your issue too (not sure) it is quite a bit cheaper and faster to do then a gear swap.
 

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R/Tless...for now
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Discussion Starter · #12 ·
just a quick thought. my truck has 3.92's and a 3.9 v6 so it may be diferent with your set up.

I put my 265/75r16s (just a we bit under 32's) on and noticed some gear hunting. when I got home i adjusted the tire size with my superchips 3815 to adjust the speedo, but it seemed to fix the tranny hunting for the proper gear as well.

If this where to work for your issue too (not sure) it is quite a bit cheaper and faster to do then a gear swap.
I want to do that as well, just need to find a cheap superchips tuner. Would be great if that fixed the trans hunting issue, but I still want to do the gear swap, 3.55's and 32's just suck, altho the V8 does help make it more tolerable.
 

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Time for Johnination
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Eventually I would like to regear my truck too. But with the V8 and the manual tranny it isnt that bad. My friend cherokee has a 3 inch lift and the same size tires i do (32x11.50-15 mud tires) with the auto transmission and he said he tops out at like 80-85 on the free way, and he has the V6 6.0L. But on the other hand, off road his cherokee climbs hills better than my truck. i have a lot more torque than he does so my open diff. just breaks loose and spins while he can creep up the hills. But, a locker will fix that problem. :D
 
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