What gear ratio for 2004 LJ with 33 inch tires and 42RLE?

Which gears for 42RLE and 33s for highway optimizaiton

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Abrao865d

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Jun 5, 2020
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Location
Las Vegas, NV
Hello everyone!

So I have owned my LJ for 3 years and I love it off road, but getting to the trails is a different story. I have stock gears with the 42RLE Auto and 33" tires and it does fine on flat highway but get a hill or a headwind and it's a mess. I typically drive 70-75mph. I want to make this Jeep a little more enjoyable on the highway so maybe I don't hesitate to take it on a weekend trip to Flagstaff or Utah or Huntington Beach with the wife kid and dogs.

That being said I am in the market for a re-gear local shop quoted $1600 out the door which didn't seem unreasonable.

From my research a lot of folks are suggesting 5.13s for the 42RLE since the OD gear is so tall. I haven't been able to find any videos on YouTube and very few 4spd TJ/LJ who have actually put 5.13s with 33" tires.

Guy at the gear shop said its way too much gear he said he's got a 04 TJ with 4.56 and 35s and the same auto and the RPMS are about at high as you would comfortably want to go. Definitely conflicting information from what's on the forum.

Please anyone with a TJ/LJ 33" tires 42RLE and gears please tell me what gears you went with and your real world experiences related to highway driving and power. I only want to drop the money once on this. Thank you for your help!

-Brandon
 
Yep 5.13. If anyone says that's way too low of a ratio just realize they don't understand the 42RLE transmission you have whose Overdrive ratio is .69 which cuts the rpms to only 69% of what they'd be without Overdrive, which drops the rpms way too low. A 5-speed manual transmission like the AX-15 only has a .78 OD ratio so it gives higher rpms which make it perfect on the freeway with higher ratios like 4.56 or 4.88. But with your 42RLE, do go with 5.13. You'd hate life after regearing it if you paid attention to someone recommending 4.56 etc. since it works so well with a 5-speed manual transmission. Make sense?
 
Some people like cruising the freeway with the tach at 2700 rpm.

Some people don't.

If this Jeeper wants to cruise on the freeway with his tach sitting at 2700 rpm at 75 mph all they have to do is press that little button on the dash and see what it's like. No tricks, no internet bull, no, I'm right you're wrong. Just test it and see if you like it.

If you want to see what the different gear ratios will be like you can play around with this gear ratio calculator. You can put in any speed or gear ratio and see what it's going to be like.

Grimm Jeeper
 
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I have 4.56's on 33" with a NV3550. I think I should have gotten 4.88's at minimum. Listen to the 5.13 advice. Rarely do you hear folks complain about gearing too low, but often you hear our laments about being too high. Well, I am okay with being too high, but you get the picture.
 
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Abrao865d said:
That being said I am in the market for a re-gear local shop quoted $1600 out the door which didn't seem unreasonable.
Click to expand...

I just had Revolution 5.13s installed for ~$1100 OTD in SoCal so check around.

Abrao865d said:
Guy at the gear shop said its way too much gear he said he's got a 04 TJ with 4.56 and 35s and the same auto and the RPMS are about at high as you would comfortably want to go. Definitely conflicting information from what's on the forum.
Click to expand...

That in combination with the price would make me hesitant to utilize that shop for a regear.
 
Now I am really confused because the ratio calculator says I should be way lower RPM in OD at 70MPH with 3.73. Im at 2500rpm at 70. Shop confirmed I have 3.73. I am going to 5.13. What gives here???
IMG_4377.jpeg
 
Abrao865d said:
Now I am really confused because the ratio calculator says I should be way lower RPM in OD at 70MPH with 3.73. Im at 2500rpm at 70. Shop confirmed I have 3.73. I am going to 5.13. What gives here???
View attachment 168686
Click to expand...
Sorry this is only going to be a distraction but my OCD noticed that if you had taken that picture only two miles later then your trip meter would have read 373 to match your gearing 😋
 
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my tires are about 60% tread I am not sure its its the appropriate way to measure but they are 31" vertically with the weight on them and 31.5" horizontal in diameter but even at 31 in the calculator its way off from what Im seeing
 
Speedo is off or tire info is off. You can look up your tires revs per mile to eliminate that variable.
 
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