04 Rubicon 42RLE to AX-15 transmission swap

Id Regear to 5.38 not sure I'd stop at 5.13. 33 or 35 inch tire. Not sure you'd really feel a difference between the two gear ratios.
 
What’s the general consensus? Is 5.38 too low for 33’s? Tires are brand new but could see doing 35’s on the next set.... if I’m regearing......🤔
 
What’s the general consensus? Is 5.38 too low for 33’s? Tires are brand new but could see doing 35’s on the next set.... if I’m regearing......🤔
I'd go 5.38 for 33's in a heartbeat, especially since you're likely going to have 35's in the future. Heck I'd like to have an even deeper ratio than my present 5.38's for my 35's so I believe you'd love 5.38 for 33's. Yes I'm thinking of how it will drive on the highway, I'm not making that recommendation as an offroad ratio, it's the right one for the highway. It'll be superb offroad too though.
 
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I'd go 5.38 for 33's in a heartbeat, especially since you're likely going to have 35's in the future. Heck I'd like to have an even deeper ratio than my present 5.38's for my 35's so I believe you'd love 5.38 for 33's. Yes I'm thinking of how it will drive on the highway, I'm not making that recommendation as an offroad ratio, it's the right one for the highway. It'll be superb offroad too though.

Well now you have me concerned, have your recommendations been mainly with road in mind? This is a trail rig, makes a few trips a year to the ice cream shop with the kids but 90% of it’s job is off road. The only place I’m concerned is sand hills, (and by hills I mean dunes) all my other wheeling can be done with lower ranges. Will 5.38’s be too low for sand/mud keeping in mind I lock out OD?

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It is possible to wire the OD switch
While technically possible if you know how to come up with a latching circuit it's not something many would be able to come up with. The Overdrive switch is not a simple on-off switch like many assume it is. It's a momentary contact switch that does nothing but provide a momentary ground connection to the PCM to toggle the Overdrive on & off. Every time the ignition is turned off the PCM re-enables the Overdrive.
 
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While technically possible if you know how to come up with a latching circuit it's not something many would be able to come up with. The Overdrive switch is not a simple on-off switch like many assume it is. It's a momentary contact switch that does nothing but provide a momentary ground connection to the PCM to toggle the Overdrive on & off. Every time the ignition is turned off the PCM re-enables the Overdrive.
Yeah I had some plans drawn up to have the shifting action provide the momentary ground as it came out of park to reverse or drive, but I regeared instead :)
 
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Don't overthink this, I was only trying to put your mind at ease that you might be getting screaming high highway rpms by going with 5.38.

2268 rpm at 60 mph with 5.38’s with the .69 OD. Heck, I call that darn near perfect 😁

5.38’s it is, wish I could ride in a rig with my setup before pulling the trigger, guess I didn’t get into this hobby to save money 🤪
 
I thought as much on the pulse.
It would be nice if the default was no overdrive , man it goes from being nearly too much to too little.
 
Just ordered a set of Revolution 5.38’s, anyone have a link to a good tutorial or install video? I know everyone says to take it to a reputable shop, I try to do as much as I can myself and being a machinist I have all the precision measuring equipment to check the tolerances. It can’t be that hard right?😂
 
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I'll post a few pics and a hint or two tomorrow morning. Right now I am on my way to make my second (and last) Martini for the evening. 🤣Regearing a Rubicon takes special technique but nothing insurmountable. There's a lot overall to get it right.
 
X2 to taking it to a shop @tigman250 there's a lot more to regearing than most suspect. Not even many full-time mechanics do ring & pinion installations and not all who do are able to do it successfully 100% of the time. When not done perfectly the new gears will be toast.

Regearing a Rubicon is no different than on other Jeeps but you have to have to know about an extra Rubicon-only technique to get the carrier properly reseated into the housing. The locker sensor is right behind the carrier and it WILL get positioned incorrectly if you just insert the carrier like you do in other axles. The sensor will get positioned on the wrong side of the locker actuator plate which will jam the locker into its locked position. It happened to me during my regear to 5.38 years two years ago.

Thankfully Rubicon Gear & Axle told me what the problem was when I called them for assistance and they told me how to use the "toothpick technique" to get the sensor to seat on the correct side of the locker actuator plate.

You simply trim a round toothpick to the length that will hold the sensor fully extended, well out past its normal spring-loaded resting position. You attach a string or piece of fishing line to that piece of toothpick so you can pull it out once the locker is properly seated back into the housing. Once you pull the toothpick out it will be on the correct side of the actuator plate and it'll work correctly.

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The 42RLE gets a bad rap for two reasons:

1. Not having the proper gearing
2. '05 - '06 PCM problems

Having the right gearing will help put a smile back on your face! In case you haven't done it yet, installing a good transmission cooler, along with a temperature gauge, will help the 42RLE live a longer healthier life.
 
The 42RLE gets a bad rap for two reasons:

1. Not having the proper gearing
2. '05 - '06 PCM problems

Having the right gearing will help put a smile back on your face! In case you haven't done it yet, installing a good transmission cooler, along with a temperature gauge, will help the 42RLE live a longer healthier life.

I put on the largest trans cooler I could jam in front of the radiator and have a pillar gauge for trans temp monitoring temp going out to cooler. Generally stays between 150-180 on normal trail rides, only spikes above 180 on back to back hill climbs, if it’s above 180 for any length of time I stop and let it cool off just to be safe 😎

Excited to get them in, I’m hearing I’ll love the 42RLE after it’s geared properly, I hope so because I sure don’t think much of it now LOL
 
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Generally stays between 150-180 on normal trail rides, only spikes above 180 on back to back hill climbs, if it’s above 180 for any length of time I stop and let it cool off just to be safe 😎

That's consistent with what I see. With a combination of a hot summer days and long hill climbs, I've seen my temps rise as high as 188°. I've thought about adding the Derale fan cooler, but there's too much sloppy stuff where I live!
 
That's consistent with what I see. With a combination of a hot summer days and long hill climbs, I've seen my temps rise as high as 188°. I've thought about adding the Derale fan cooler, but there's too much sloppy stuff where I live!

I put in the Derale electric fan kit, thought it would be nice to 1. Save the parasitic power loss and 2. Have override switches so I could force it off for water crossings and force it on to quickly cool the trans. Wound up putting it back to stock because I couldn’t get it to come on and off correctly. The thermostat that came with it basically made it run constantly so I put in an adjustable thermostat but because the sensor was in the radiator and the fan worked so well and pulled the heat so quickly the dumb thing was off and on constantly. Got tired of tweaking it so went back to the roaring, leaf/dust blowing, water spraying clutch fan LOL
 
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