Gearing suggestions for 2001 TJ with 31s?

PNW Nick

PNW Nick

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My 2001 Jeep tj is pretty much stock all around, i have a Dana 30 in the front and 35 in the back. i would like to run 31s at max, so i looked around and some other people have told me to run 4.56 gears for best results, i have some products in mind but i would like to get some second opinions on what to get.
 
Do you have the 3 speed auto? 4.56 would probably be too deep with that and stock tires.
What gear ratio do you currently have?

Consider installing lockers at the same time as regearing. The labor cost isn’t much more than just regearing, but would save you on the order of $1,000 in labor versus regearing and adding lockers at different times. Lockers will make you much more capable off-road on stock tires, possibly even more so than a Jeep on 35s without lockers.
 
Steel City 06 said:
Do you have the 3 speed auto? 4.56 would probably be too deep with that and stock tires.
What gear ratio do you currently have?

Consider installing lockers at the same time as regearing. The labor cost isn’t much more than just regearing, but would save you on the order of $1,000 in labor versus regearing and adding lockers at different times. Lockers will make you much more capable off-road on stock tires, possibly even more so than a Jeep on 35s without lockers.
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to be honest i dont take my jeep off road too much, mostly at the beach, i was looking to run bigger tires , so i assumed i need to compensate the gears, its a 3 speed auto. honestly its used on the highway more than at the beach, so something that gives good on both on and off. the dana 30 is 3.07 and so does the 35
 
3.73 would probably be a good ratio for 31s and the 32RH, assuming you have the 6 cyl. You could go 4.10, but 4.56 would probably rev too high on the highway. If you think you will likely go a little larger (e.g., 32s) in the future, 4.10 might be a good option.

The 32RH has no overdrive so it requires much less axle gearing than other transmissions. The 42RLE has a 0.69 overdrive so you’ll see people going as deep as 4.88 on 31s with that transmission.

Consider getting at least a limited slip carrier for the rear, perhaps a selectable locker. Driving on the beach, if you’ve ever gotten stuck, you’ll notice only one wheel on each axle actually spins. With a locker, you can force both wheels on that axle to spin, getting you unstuck. A limited slip does the same thing automatically, but the amount of force it provides is limited. Going from unlocked axles to locked axles is as impressive as going from 2WD to 4WD. A decent limited slip carrier won’t cost you too much more, maybe 4-500 more. A selectable locker would probably run you ~800 extra (per axle, but you can always do only one). Auto lockers are also available, but are better for the front axle than the rear on-road.
 
Steel City 06 said:
3.73 would probably be a good ratio for 31s and the 32RH, assuming you have the 6 cyl. You could go 4.10, but 4.56 would probably rev too high on the highway. If you think you will likely go a little larger (e.g., 32s) in the future, 4.10 might be a good option.

The 32RH has no overdrive so it requires much less axle gearing than other transmissions. The 42RLE has a 0.69 overdrive so you’ll see people going as deep as 4.88 on 31s with that transmission.

Consider getting at least a limited slip carrier for the rear, perhaps a selectable locker. Driving on the beach, if you’ve ever gotten stuck, you’ll notice only one wheel on each axle actually spins. With a locker, you can force both wheels on that axle to spin, getting you unstuck. A limited slip does the same thing automatically, but the amount of force it provides is limited. Going from unlocked axles to locked axles is as impressive as going from 2WD to 4WD. A decent limited slip carrier won’t cost you too much more, maybe 4-500 more. A selectable locker would probably run you ~800 extra (per axle, but you can always do only one). Auto lockers are also available, but are better for the front axle than the rear on-road.
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so 3.73 sounds like a good plan. im kinda on the fence with tho locker, i understand why people should get them but ive only been stuck once, and i aint doing that again. but ill see how much more i can shell put for it. also for changing to a 3.73 do i need a master kit to replace it or would the stock carrier work for it as well
 
I have the same spec and am running 31s now. I honestly feel no difference without regearing. I would give it a try and then decide. I also did not really need to change the speedo. GPS speed tracking is spot on but mine came with 30s to begin with.
 
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primetime4 said:
I have the same spec and am running 31s now. I honestly feel no difference without regearing. I would give it a try and then decide. I also did not really need to change the speedo. GPS speed tracking is spot on but mine came with 30s to begin with.
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This is a good point. One doesn’t need to do it at the exact same time as the tires.


You’re only looking at about a 7% reduction in RPM if you go from ~29s to 31s, so while it’s not ideal, you should still be okay to drive for a while. You will still want to regear eventually, but you’d be fine driving on the new tires and stock gears for a while. Won’t hurt anything, but your acceleration will suffer a bit until you do regear
 
3.73's were a pretty common factory ratio. I would start by looking for some used axles to swap in, 'cause it'll be cheaper and I wouldn't have to deal with a shop to do the work.
 
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