Differentials and Gears

TheShakes90

TheShakes90

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So after doing a ton of research at work last night, don't judge to much, and a little more at home I'm writing this to get my thoughts in order and maybe get a few things explained a little better.

Vehicle: 2006 LJ with Dana 30/44, 42RLE, 33" tires, and stock differentials and transfer case.

Stuff I understand mostly:
I should be using 5.13, 4.88, or 4.56. Using the GrimJeeper calculator I'm thinking 4.88 or 4.56 to keep the revs sub 2500 when I'm at highway speeds
Eaton Truetrac and Torsen differences are splitting hairs
Between reading Blaine's comments on dealing with OX and my newish knowledge on cables Manual lockers are out
Air vs Electric is more asking where I'll be and what I'll be doing to figure out what my situation calls for
Lunchbox and Detroit's aren't the greatest for my common snow drives, but Truetrac styles can be good

Stuff I need help on:
I read Jjvw's write up on the York air system and found some old Jerry posts to push me in the right direction, if I choose to go air is there an easy reducer to get the PSI down for the lockers? I just took a pneumatics class so I know they exist but the ones I learned about were a little big for the application
I'm probably going 4.56 for the time, though that'll change every other second until I spend the money, I seem to recall seeing the Non-Rubi differentials require nonstandard gears, thick cuts I think, if this is true I'm guessing I should get the gears and carriers done in one go.

There will definitely be more when my brain isn't on overload any more. If anyone can confirm I'm at least pointing the right way it'll be greatly appreciated
 
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TheShakes90 said:
So after doing a ton of research at work last night, don't judge to much, and a little more at home I'm writing this to get my thoughts in order and maybe get a few things explained a little better.

Vehicle: 2006 LJ with Dana 30/44, 42RLE, 33" tires, and stock differentials and transfer case.

Stuff I understand mostly:
I should be using 5.13, 4.88, or 4.56. Using the GrimJeeper calculator I'm thinking 4.88 or 4.56 to keep the revs sub 2500 when I'm at highway speeds
Eaton Truetrac and Torsen differences are splitting hairs
Between reading Blaine's comments on dealing with OX and my newish knowledge on cables Manual lockers are out
Air vs Electric is more asking where I'll be and what I'll be doing to figure out what my situation calls for
Lunchbox and Detroit's aren't the greatest for my common snow drives, but Truetrac styles can be good

Stuff I need help on:
I read Jjvw's write up on the York air system and found some old Jerry posts to push me in the right direction, if I choose to go air is there an easy reducer to get the PSI down for the lockers? I just took a pneumatics class so I know they exist but the ones I learned about were a little big for the application
I'm probably going 4.56 for the time, though that'll change every other second until I spend the money, I seem to recall seeing the Non-Rubi differentials require nonstandard gears, thick cuts I think, if this is true I'm guessing I should get the gears and carriers done in one go.

There will definitely be more when my brain isn't on overload any more. If anyone can confirm I'm at least pointing the right way it'll be greatly appreciated
Click to expand...

4.56 gears are typically recommended for 33" tires and either 5-sp transmission. I think you want 4.88 at a minimum with your 42RLE, and some like 5.13, particularly for a heavier LJ. No reason to aim for sub-2500 rpms at highway speed. Cruising at 70 mph, you would probably realize better fuel economy above 2500 rpm than below.
 
rouxbicon said:
4.56 gears are typically recommended for 33" tires and either 5-sp transmission. I think you want 4.88 at a minimum with your 42RLE, and some like 5.13, particularly for a heavier LJ. No reason to aim for sub-2500 rpms at highway speed. Cruising at 70 mph, you would probably realize better fuel economy above 2500 rpm than below.
Click to expand...
X’s 2. Go deep with the 42RLE as it has a tall overdrive and somewhat poor performance out of the 4.0, horsepower wise.
 
I just swapped to 5.13 with the 42RLE and 33" tires, cruising RPM around 2650 at 70 mph. It wouldn't have been worth it go with anything less.
 
5.13 it is.

Now for carriers, I'm planning on upgrading to a Torsen/TrueTrac rear since if I'm understanding correctly Dana 44 carriers are either 3.73 and down or 3.92 and up.

For the Dana 30 am I understanding correctly that the carrier I have now with 3.73 gears should work for 5.13? Looking at various carriers for the 30 it appears that there's the option of 3.54 and down or 3.73 and up.
 
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TheShakes90 said:
5.13 it is.

Now for carriers, I'm planning on upgrading to a Torsen/TrueTrac rear since if I'm understanding correctly Dana 44 carriers are either 3.73 and down or 3.92 and up.

For the Dana 30 am I understanding correctly that the carrier I have now with 3.73 gears should work for 5.13? Looking at various carriers for the 30 it appears that there's the option of 3.54 and down or 3.73 and up.
Click to expand...
Good decision to go with 5.13, 4.88 would have been a mistake.

Having run front and rear Truetracs in my previous TJ, what type of wheeling are you doing? Truetracs are superb for icy/slick paved streets and for slick trails that are icy or flat enough that you can keep all four tires on the ground. But if you want your Jeep to be able to handle trails that are uneven enough to lift a tire or two up off the surface, a Truetrac becomes useless. For that level of trail you want a locker (s). My previous TJ's Truetracs proved so useless for the offroading I enjoy that I replaced both with lockers and never looked back.
 
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@Jerry Bransford currently no wheeling, between work and school I barely sleep or do nice relaxing day trips on the bike. Right now it's purely Illinois winter/t storm driver with plans to move to Montana, Utah, Colorado area.

If I had to describe the area's I want to go it's very much like Jjvw's write up, anywhere I can with a daily driver.

Also since it sounds like you're heavily recommending diving into selectables right away question. I've seen past posts from you about the York compressor, I understand at least enough to know it's a good idea. Will it be overkill for air lockers? I've been considering if I go that route install a small tank behind the seats with a pressure regulator if necessary for the lockers
 
As much as I like my York, there are far easier and less expensive ways to quickly fill tires and power lockers. ;)
 
@jjvw I don't doubt this at all, I've also considered an ARB and Viair compressors. With the 33s being the largest for quite a while, do you have a set up type you would recommend?

Now that some of this stuff is sorted onto carriers. I think for the time I'll use a cheaper open carrier so when I get to where I end up at I can test the waters and see what might work best.
 
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I started out with the Viair 88p. It was inexpensive, slow and reliable. Both Viair and ARB will have faster compressors that are also reliable. Basically, you want something reliable. Speed is going to cost more.
 
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