Axle Questions

[2nd TJ]

I have read several threads about changing my axle ratios. Between the forum information and asking multiple shops that deal with axles, I am blah!!!

Jeep info:
2004 Sport
4.0 I6
Automatic w/overdrive, also have the switch to turn off the OD.
Currently has the stock 3.73
Dana 30 front and Dana 35 in the back

The lift will be a 3.5 inches, and I will run 33 inch tires. Neither now or in the future will I ever go to 35 inch tires. If it matters, additional extra weight from bumpers, rear rack, gas can containers, inside storage rack, and winch will be 280lbs to 300lbs. This is my every day vehicle, but during the weekends I am either in the Southern California mountains or the Mojave Desert. When I am prospecting I usually have another 50lbs to 200lbs of additional gear.

My thought process is 4.10, but some are saying 4.56. I also want to go 70mph-75mph when I need to. Currently my 3.73 and 31's allow me to do that easily.

Thank you for the help.

 

[Good Hope]

Be prepared for a floodgate of opinions on this well debated topic. I have the same mechanical setup as you and am very happy with my 4.88 gears. I also live in Big Island Hawaii where everywhere I drive is a hill and the maximum speed limit is 65mph. For your use, 4:56 would probably work fine, but you will appreciate the extra apparent extra power if you go 4:88.

 

[Jerry Bransford]

Your 42RLE transmission needs much lower axle ratios than is normal for other transmissions due to its stupid steep .69 Overdrive ratio. For 33's I'd go with 5.13 which would be ideal. 4.88 at a minimum! Not even my 5.38 is perfect/quite enough for my 35's though it's ok. Yes I'm talking about its highway rpms and performance.

You'd never regret 5.13, especially on the highway.

I bought my current TJ used with 35's, 42RLE, and 4.88 in the axles. The engine was always lugging, it was terrible on the highway, and the best mpg it ever got was 11 mpg. I regeared it to 5.38 and everything improved dramatically.

Even its highway mpg jumped up to 14.6 mpg since the engine was no longer lugging after installing the 5.38 gears.

 

[GPK03X]

Because of the steep overdrive of your transmission you want all the gear you can get! 5.13 is the recommended ratio. 4.10 or 4.56 would be a complete waste of money!

 

[jjvw]

513

 

[Ocho]

513

now now, that's not low enough. gotta go at least 5.38

 

[PNW_LJ]

now now, that's not low enough. gotta go at least 5.89

FIFY

 

[Ocho]

FIFY

thanks for the fix! would hate for OP to end up with a shitty overdrive rpm with those 5.13s......... go big or go home!

 

[2nd TJ]

Your 42RLE transmission needs much lower axle ratios than is normal for other transmissions due to its stupid steep .69 Overdrive ratio. For 33's I'd go with 5.13 which would be ideal. 4.88 at a minimum! Not even my 5.38 is perfect/quite enough for my 35's though it's ok. Yes I'm talking about its highway rpms and performance.

You'd never regret 5.13, especially on the highway.

I bought my current TJ used with 35's, 42RLE, and 4.88 in the axles. The engine was always lugging, it was terrible on the highway, and the best mpg it ever got was 11 mpg. I regeared it to 5.38 and everything improved dramatically.

Even its highway mpg jumped up to 14.6 mpg since the engine was no longer lugging after installing the 5.38

Thank you.

 

[2nd TJ]

Because of the steep overdrive of your transmission you want all the gear you can get! 5.13 is the recommended ratio. 4.10 or 4.56 would be a complete waste of money!

Thank you.

 

[jjvw]

now now, that's not low enough. gotta go at least 5.38

FIFY

I'll let you two explain how to make 538 and 589 happen

 

[HornedToad]

5.13s. Thats what I have in mine and back when I had 33s it was nearly perfect. Now with 35s it is pretty lacking on the highway but it’s the lowest my axles will let me go.

 

[PNW_LJ]

I'll let you two explain how to make 538 and 589 happen

@Ocho, ladies first.

 

[Ocho]

@Ocho, ladies first.

pussy

 

[Ocho]

I'll let you two explain how to make 538 and 589 happen

just a few more dollars for some new axles to get that perfect gearing

 

[JMT]

I have read several threads about changing my axle ratios. Between the forum information and asking multiple shops that deal with axles, I am blah!!!

Jeep info:
2004 Sport
4.0 I6
Automatic w/overdrive, also have the switch to turn off the OD.
Currently has the stock 3.73
Dana 30 front and Dana 35 in the back

The lift will be a 3.5 inches, and I will run 33 inch tires. Neither now or in the future will I ever go to 35 inch tires. If it matters, additional extra weight from bumpers, rear rack, gas can containers, inside storage rack, and winch will be 280lbs to 300lbs. This is my every day vehicle, but during the weekends I am either in the Southern California mountains or the Mojave Desert. When I am prospecting I usually have another 50lbs to 200lbs of additional gear.

My thought process is 4.10, but some are saying 4.56. I also want to go 70mph-75mph when I need to. Currently my 3.73 and 31's allow me to do that easily.

Thank you for the help.

513 for a Dana 30/Dana 35 or Dana 30/Dana 44 combo.

 

[2nd TJ]

It seems like 5.13 seems to be the number with 33 inch tires and my transmission. Have there been any mechanical issues since that set up is 24% higher RPM's compared to the original set up?