Re-gear done (amazing)

[CptnMurica]

The 4.56 gears have been working real good w the 2.5 and 33s I’m real light just not a lot added. After wheelin a lot since they have settled down a bit. Still get to use 5th I even hit 80+ on the Highway one time. anybody thinking of 4.88 or especially 5.13 would probably need a trailer with a similar set up.

 

[Jerry Bransford]

4.88 is, by far, the most common recommendation for 33's with 5-speed with the 2.5 engine.

 

[CptnMurica]

4.88 is, by far, the most common recommendation for 33's with 5-speed with the 2.5 engine.

I could see it going there. Still works good. Seems right on the edge Jerry.

 

[Mudflat]

After spending a lot of time in here reading all the info I went for 4.56s. I have to say that this is great. My 4 hamsters have come alive. 4wdl is a bulldog On the trail. Off the line it goes. And keeps up with traffic. Picked up around 4mpg. It’s pricey but if ya haven’t done it and your running over sized tires this is where it’s at.

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Welcome to the 4.56 club. If you haven’t already done it, you need to change your speedometer drive gear for 4.56 & your tire diameter. It took the 19 tooth gear for my 33” tires. Here’s the chart to help you find what you need.

 

[CptnMurica]

Welcome to the 4.56 club. If you haven’t already done it, you need to change your speedometer drive gear for 4.56 & your tire diameter. It took the 19 tooth gear for my 33” tires. Here’s the chart to help you find what you need.

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That’s interesting Ty man

 

[Mudflat]

My LJ regearing is scheduled. Looking forward to it. Right now I have to drive my 4sd like a 3sp - 4th is utterly useless (I just have to remember to hit the OD switch every time I leave town). That said, I assume having 3 lower gears instead of 2 will also help performance at lower speed a lot. Only one good thing I can say about my current gearing - doing 80 in third is no problem, plenty of power band left.

If you don’t already have it, you might as well add some kind of limited slips or lockers & chromoly axles. Since the techs are already in there changing gears, it will save you a lot of money in labor costs. I went with True Track limited slips, but to each his own.

 

[Mudflat]

Very nice! 3.73 here also on 31s, I image going to 4.10 wouldn't be that much of a change. Would like 33s eventually & the truetrac as well.
I have been running around in 4th trying to get out of the habit of hitting 5th on the surface streets around 45 mph and turning like 1500 rpm. 4.56 would probably be the way to go.

I changed mine from 3.07 to 4.56 & added True Track limited slips front & rear & chromoly axles. My tires are 33”. Here’s some “before & after” data on my gear change but might help you decide.

 

[old jeep new to me]

After spending a lot of time in here reading all the info I went for 4.56s. I have to say that this is great. My 4 hamsters have come alive. 4wdl is a bulldog On the trail. Off the line it goes. And keeps up with traffic. Picked up around 4mpg. It’s pricey but if ya haven’t done it and your running over sized tires this is where it’s at.

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What was the price tag, I also have a little 4 also, I really mostly go no more than 30 to 40 minute drives because it just has no power especially on the highway. If it makes that much of a difference I may look into that. I do have an automatic transmission though.

 

[Jerry Bransford]

What was the price tag, I also have a little 4 also, I really mostly go no more than 30 to 40 minute drives because it just has no power especially on the highway. If it makes that much of a difference I may look into that. I do have an automatic transmission though.

What size tires?

 

[old jeep new to me]

What size tires?

I have 32s on and I won't change that.

 

[Jerry Bransford]

I have 32s on and I won't change that.

32's will definitely make the 2.5 engine/automatic transmission struggle more. Two possible fixes involve either going back to the smaller factory size tire or regearing your axles to a lower ratio to raise the engine rpms back up to where they were with the smaller factory size tires. The cheapest option would be smaller tires. To keep the bigger 32's and get more acceptable performance would require the axles to be regeared. Costs for that vary on how competitive your local 4x4 shops are but $1600 is mid-range in terms of the cost to do that. I've regeared three times since buying my first TJ in 1996 and each time I felt the cost was more than worth it in terms of it no longer being a "dog" on the road. The last time I regeared even my mpg went from sub-12 to 14.6 on the highway since the engine was no longer lugging at highway cruising speeds.

But make no mistake the 2.5 engine/automatic transmission combination is not known for great performance even when the axles are geared properly.