Has anyone with the 4x4 changed their gearing? I am considering changing mine to something around 4.30, the highway mileage really bites right now. If anyone with the 4x4 has any thoughts please let me know.

I've changed a many of gears. Are you speaking about having it changed at a shop or you doing it? You'll also have to reprogram your speedo.

Yes the 5.13 are really low and I wish they offered a choice with the 4x4 besides 5.13 or 5.38. Try 4x4 low range in reverse with the allison can't get above a few mph (My 5500 4x4 is used only for plowing)

I am only getting 8-10mpg at 65mph, at 5-10k above sea level.... but I don't make that trip often at all.

Should be able to go to any 4wd shop and get gears done. Dana 60 up front and Dana 135 in the rear. "might" have to buy a new carrier for the front and/or rear if you want to go lower than say 4.56 or so, but I don't know for sure. You could upgrade to detroit lockers or ARBs at that time.

Cost, What I have paid for gears in the past $250-300 per axle setup/install. I am guessing $200-250 per axle for the gears themselves. So figure at least $1100 to $1300 or so for just gears... Add carriers or lockers and it could add 600-1800 on top of that.

? is how long would it take to pay that back? If you are towing heavy I don't think that you would want to go much taller than 4.4 or certainely not taller than 4.10. If you got 10% improvement in mileage it would barely would pay for itself in 100k miles, MAYBE.

Just my thoughts.

I have always found that actual economy is not driving force for differential improvement mods.. I look at the revs per mph, or the noise per mph, and act accordingly.. Having an excessive engine noise at 65 mph, is the reason I will probably get my gears changed sometime in the future. I would do it now, but funds are short this time of year. I have 4.4 in, which gives me 2k revs at 64 mph.. I would prefer to hit the 2k revs at over 70.

Could you change to taller tires.....The tires on the 4500/5500's are real low profile. Is there another size that has a taller aspect ratio?

Michelin makes a 285/70R19.5 tire that is 35.2" tall instead of the stockers that are only 33.5" tall.

Might be a better choice, but then 6 new Michelin tires arent' that cheap either.

If it was 2WD, a gear swap may be cheaper. Then again, depending on the miles on the OEM tires, you may be able to sell them!

The way the flat bed is mounted on my truck, I have no room for taller tires, even if they would only be 1 inch nearer.. I can't raise the bed any, as the total fool that fitted it welded it on.

Michelin makes a 285/70R19.5 tire that is 35.2" tall instead of the stockers that are only 33.5" tall.

Might be a better choice, but then 6 new Michelin tires arent' that cheap either.

If it was 2WD, a gear swap may be cheaper. Then again, depending on the miles on the OEM tires, you may be able to sell them!
Probably would fit on a 4x4 with a flatdeck like mine.... but then again those tires are probably $300 or so a piece...

Arc has a 4x4 which come with 5.13 stock, the only other choice is 5.38

My believe is that when the truck was designed .. it was not designed for top end... it was looked at taking off down the road fully loaded... the same goes for trucks up to class 8... ... they have a lot more hp to get a top end.. but for grunt pulling power you have a lower rear end

One thing you could possilbly look into a 2 speed rear end... but that is a lot more costly to swap out

I believe that the international that I had which was a 2 speed rear end with a ratio of 4.56 and a 6.13.. could be wrong

Pete

Pete

I have been looking for anything with a two speed rear, that would be an advantage to my current 4.44 ratio. The best I have seen has been higher that that for both ratios. A perfect one for me would be 4.50 to 3.75 but I am thinking that the speedo comes from either the tranny or electronicly from the shaft.. A two speed rear would make worthless the stock speedo...

You were right on with your cost est, I was quoted $1,000-$1,200 per diff. It looks like this spring I'll cough up the bucks, it's actually cheaper than I was anticipating. I believe over the life of the truck it will really save a lot of un-needed wear. I have no intentions on ever towing what it is rated for, I'd like to end up with a ratio around 4.30. On top of that a set of taller summer tread might also be an idea, then stud the stockers for winter.



Yes the 5.13 are really low and I wish they offered a choice with the 4x4 besides 5.13 or 5.38. Try 4x4 low range in reverse with the allison can't get above a few mph (My 5500 4x4 is used only for plowing)

I am only getting 8-10mpg at 65mph, at 5-10k above sea level.... but I don't make that trip often at all.

Should be able to go to any 4wd shop and get gears done. Dana 60 up front and Dana 135 in the rear. "might" have to buy a new carrier for the front and/or rear if you want to go lower than say 4.56 or so, but I don't know for sure. You could upgrade to detroit lockers or ARBs at that time.

Cost, What I have paid for gears in the past $250-300 per axle setup/install. I am guessing $200-250 per axle for the gears themselves. So figure at least $1100 to $1300 or so for just gears... Add carriers or lockers and it could add 600-1800 on top of that.

? is how long would it take to pay that back? If you are towing heavy I don't think that you would want to go much taller than 4.4 or certainely not taller than 4.10. If you got 10% improvement in mileage it would barely would pay for itself in 100k miles, MAYBE.

Just my thoughts.